PA-600 4-79-026
1a\ 1979
x>EPA
Climatological Summaries of the Lower Few
Kilometers of Rawinsonde Observations
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This report has been assigned to the ENVIRONMENTAL MONITORING series
This series describes research conducted to develop new or improved methods
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This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161
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EPA-600/4-79-026
May 1979
Climatological Summaries of the Lower Few
Kilometers of Rawinsonde Observations
by
George C Holzworth and Richard W Fisher
Meteorology and Assessment Division
Environmental Sciences Research Laboratory
Research Triangle Park, North Carolina 277II
U S ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Environmental Sciences Research Laboratory
Research Triangle Park, North Carolina 27711
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DISCLAIMER
This report has been reviewed by the Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
AFFILIATION
Messrs. Fisher and Holzworth are meteorologists in the Meteorology and
Assessment Division, Environmental Sciences Research Laboratory, U.S. Environ-
mental Protection Agency, Research Triangle Park, North Carolina 27711.
They are on assignment from the National Oceanic and Atmospheric Administration,
U.S. Department of Commerce.
ACKNOWLEDGMENT
The data processing techniques and summaries that were generated in
connection with this report were developed in the Automated Data Processing
Services Division of the National Climatic Center at Asheville, North
Carolina. It has been a distinct pleasure to work directly with Messrs.
Richard M. Davis, C. Ray Barr, Harold M. Craddock, and Stephen R. Doty.
ABSTRACT
Summaries of rawinsonde measurements taken twice daily at 76 United States
Weather Service stations including Puerto Rico are presented on national maps.
The summaries are based mainly on analyses of the lower 3 km of each
sounding. The data include the percentages of all inversions, surface-based
and elevated inversions separately, inversion thicknesses and the heights of
elevated inversion bases. Also included are percentages of high relative
humidities within inversions and in adjacent layers, along with percentages
of wind speeds in five categories at the surface and 300 m above the surface
for surface-based, elevated, and no-inversion cases. Finally, lapse rates
are characterized within and below inversions, and in specified layers through
1500 m for soundings with no inversion. Representative data are isoplethed
for illustrative purposes, but many figures are without isopleths because no
single variable is generally representative. Some general conclusions are:
1} inversions are virtually always present at most locations; 2) they are
almost always greater than 100 m thick and may be more than 1000 m thick;
3) shallow inversions (less than 500 m) tend to be more intense (large
AT/AH); 4) the highest relative humidities occur at the surface, especially
in surface-based inversions; 5) wind speeds with surface-based inversions are
generally slower at the surface than at 300 m and the most common surface
speed-class is 2.6-5.0 m/sec. Although the data presented in this study were
developed for use in investigations of the transport and diffusion of
atmospheric pollutants, they should be of considerable interest to others
concerned with characteristics of the atmospheric boundary layer.
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CONTENTS
Acknowledgment ii
Abstract n'
List of Figures iv
1. Introduction 1
2. Data Processing 2
3. General Discussion 3
Characteristics of Vertical Temperature Structure 4
Relative Humidity vs. Vertical Temperature Structure 12
Wind Speed vs. Vertical Temperature Structure 14
4. Summary and Conclusions 16
References 18
Appendix A. Data formats and availability 19
Figures 31
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FIGURES
Number
1. Objective scheme for specifying base and top of inversions for
various temperature profile configurations.
4.
5.
6.
Ml,
7.
9.
10.
Page
31
The 76 rawinsonde locations and their WBAN numbers used in this
study. Dates indicate observational period(s) at those stations
where it was other than 1/60-12/64. San Diego is plotted
about 250 km south of its true location to avoid overprinting.
Stations outside the contiguous United States are plotted along
the periphery. 32
Angles of solar elevation on January 15 at 1115 GMT. Negative
angles indicate that the sun is below the horizon. See Figure 2
to identify peripheral stations. 33
Angles of solar elevation on April 15 at lllb GMT. Negative
angles indicate that the sun is below the horizon. See Figure 2
to identify peripheral stations. 34
Angles of solar elevation on July 15 at 1115 GMT. Negative
angles indicate that the sun is below the horizon. See Hgure 2
to identify peripheral stations. 35
Angles of solar elevation on October 15 at 1115 GMT. Negative
angles indicate that the sun is below the horizon. See Figure 2
to identify peripheral stations. 36
Angles of solar elevation on January 15 at 2315 GMT. Negative
angles indicate that the sun is below the horizon. See Figure 2
to identify peripheral stations. 37
Angles of solar elevation on April 15 at 2315 GMT. Negative
angles indicate that the sun is below the horizon. See Figure 2
to identify peripheral stations. 38
Angles of solar elevation on July 15 at 2315 GMT. Negative
angles indicate that the sun is below the horizon. See Figure z
to identify peripheral stations. 39
Angles of solar elevation on October 15 at 2315 GMT. Negative
angles indicate that the sun is below the horizon. See Figure 2
to identify peripheral stations. 40
Number
11. Percentage of all 1115 GMT soundings with a surface-based or
elevated inversion below 3000 m AGL. See Figure 2 to identify
peripheral stations. 41
12. Percentage of winter 2315 Gf'T soundings with a surface-based or
elevated inversion below 3000 m. See Figure 2 to identify
peripheral stations. 42
13. Percentage of spring 2315 GMT soundings with a surface-based or
elevated inversion below 3000 m. See Figure 2 to identify
peripheral stations. 43
14. Percentage of summer 2315 GMT soundings with a surface-based or
elevated inversion below 3000 m. See Figure 2 to identify
peripheral stations. 44
15. Percentage of autumn 2315 GMT soundings with a surface-based or
elevated inversion below 3000 m. See Figure 2 to identify
peripheral stations. 45
16. Percentage of winter 1115 GMT soundings with a surface-based
inversion. Elevated inversion frequency is at right. See
Figure 2 to identify peripheral stations. 46
17. Percentage of spring 1115 GMT soundings with a surface-based
inversion. Elevated inversion frequency is at right. See
Figure 2 to identify peripheral stations. 47
18. Percentage of summer 1115 GMT soundings with a surface-based
inversion. Elevated inversion frequency is at right. See
-Figure 2 to identify peripheral stations. 48
19. Percentage of autumn 1115 GMT soundings with a surface-based
inversion. Elevated inversion frequency is at right. See
Figure 2 to identify peripheral stations. 49
20. Percentage of winter 2315 GMT soundings with a surface-based
inversion. Elevated inversion frequency is at right. See
Figure 2 to identify peripheral stations. 50
21. Percentage of spring 2315 GMT soundings with a surface-based
inversion. Elevated inversion frequency is at right. See
Figure 2 to identify peripheral stations. 51
22. Percentage of summer 2315 GMT soundings with a surface-based
inversion. Elevated inversion frequency is at right. See
Figure 2 to identify peripheral stations. 52
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Number
Number
23. Percentage of autumn 2315 GMT soundings with a surface-based
inversion. Elevated inversion frequency is at right. See
Figure 2 to identify peripheral stations.
24. Percentage of winter 1115 GMT soundings with an elevated inver-
sion below 3000 m AGL. Surface-based inversion frequency is
at left. See Figure 2 to identify peripheral stations.
25. Percentage of spring 1115 GMT soundings with an elevated inver-
sion below 3000 m AGL. Surface-based inversion frequency is
at left. See Figure 2 to identify peripheral stations.
26. Percentage of summer 1115 GMT soundings with an elevated inver-
sion below 3000 m AGL. Surface-based inversion frequency is
at left. See Figure 2 to identify peripheral stations.
27. Percentage of autumn 1115 GMT soundings with an elevated inver-
sion below 3000 m AGL. Surface-based inversion frequency is
at left. See Figure 2 to identify peripheral stations.
28. Percentage of winter 2315 GMT soundings with an elevated inver-
sion below 3000 m AGL. Surface-based inversion frequency is
at left. See Figure 2 to identify peripheral stations.
29. Percentage of spring 2315 GMT soundings with an elevated inver-
sion below 3000 m AGL. Surface-based inversion frequency is
at left. See Figure 2 to identify peripheral stations.
30. Percentage of summer 2315 GMT soundings with an elevated inver-
sion below 3000 m AGL. Surface-based inversion frequency is
at left. See Figure 2 to identify peripheral stations.
31. Percentage of autumn 2315 GMT soundings with an elevated inver-
sion below 3000 m AGL. Surface-based inversion frequency is
at left. See Figure 2 to identify peripheral stations.
32. Percentage of winter 111E GMT soundings with a surface-based
inversion (left) whose top exceeds 100, 250, 500, 750, 1000,
or 1500 n AGL (right, bottom to top). Isopleths show the
percentage with tops that exceed 250 m. See Figure 2 to
identify peripheral stations.
33. Percentage of spring 1115 GKT soundings with a surface-based
inversion (left) whose top exceeds, 100, 250, 500, 750, 1000,
or 1500 n AGL (right, bottom to top). Isopleths show the
percentage with tops that exceed 250 n. See Figure 2 to
identify peripheral stations.
53
54
55
56
57
58
59
60
61
62
63
34.
35.
36.
37.
38.
Percentage of summer 1115 GMT soundings with a surface-based
inversion (left) whose top exceeds 100, 250, 500, 750, 1000,
or 1500 m AGL (right, bottom to top). Isopleths show the
percentage with tops that exceed 250 m. see Figure 2 to
identify peripheral stations.
Percentage of autumn 1115 GMT soundings with a surface-based
inversion (left) whose top exceeds 100, 250, 500, 750, 1000,
or 1500 m AGL (right, bottom to top). Isopleths show the
percentage with tops that exceed 250 m. See Figure 2 to
identify peripheral stations.
Percentage of all 2315 GMT soundings with a surface-based
inversion (left) whose top exceeds TOO, 250, 500, 750, 1000,
or 1500 m AGL (right, bottom to top). Isopleths show the
percentage with tops that exceed 250 m. See Figure 2 to
identify peripheral stations.
Percentage of all 1115 GMT soundings with an elevated inver-
sion base in the range 1-3000 m AGL (left) and in smaller
ranges 1-250, 251-500, 501-750, 751-1000, 1001-2000, or
2001-3000 m AGL (right, bottom to top). Isopleths show the
percentage with bases 1001-2000 m. See Figure 2 to identify
peripheral stations.
64
65
66
67
Percentage of winter 2315 GMT soundings with an elevated inver-
sion base in the range l-300n m AGL (left) and in smaller
ranges 1-250, 251-500, 501-750, 751-1000, 1001-2000, or
2001-3000 m AGL (right, bottom to top). Isopleths show the
percentage with bases 1001-2000 m. See Figure 2 to
identify peripheral stations.
39. Percentage of spring 2315 GMT soundings with an elevated inver-
sion base in the range 1-3000 m AGL (left) and in smaller
ranges 1-250, 251-500, 501-750, 751-1000, 1001-2000, or
2001-3000 m AGL (right, bottom to top). Isopleths show the
percentage with bases 1001-2000 m. See Figure 2 to
identify peripheral stations.
40. Percentage of summer 2315 GMT soundings with an elevated inver-
sion base in the range 1-3000 m AGL (left) and in smaller
ranges 1-250, 251-500, 501-750, 751-1000, 1001-2000, or
2001-3000 m AGL (right, bottom to top). Isopleths show the
percentage with bases 1001-2000 m. See Fiqure 2 to
identify peripheral stations.
69
70
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Number
Page
Number
Page
41. Percentage of autumn 2315 GMT soundings with an elevated inver-
sion base in the range 1-3000 m AGL (left) and in smaller
ranges 1-250, 251-500, 501-750, 751-1000, 1001-2000, or
2001-3000 m AGL (right, bottom to top). Isopleths show the
percentage with bases 1001-2000 m. See Figure 2 to
identify peripheral stations.
42. Percentage of winter 1115 GMT soundings with an elevated inver-
sion base within 3000 m AGL (left) and a thickness exceeding
100, 250, 500, 750, 1000, or 1500 m (right, bottom to top).
Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
43. Percentage of spring 1115 GMT soundings with an elevated inver-
sion base within 3000 m AGL (left) and a thickness exceeding
100, 250, 500, 750, 1000, or 1500 m (right, bottom to top).
Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
44. Percentage of summer 1115 GMT soundings with an elevated inver-
sion base within 3000 m AGL (left) and a thickness exceeding
100, 250, 500, 750, 1000, or 1500 m (right, bottom to top).
Isopleths show the percentage with thicknesses exceeding bOO m.
See Figure 2 to identify peripheral stations.
45. Percentage of autumn 1115 GMT soundings with an elevated inver-
sion base within JOOO m AGL (left) and a thickness exceeding
100, 250, 500, 750, 1000, or 1500 m (right, bottom to top).
Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 1 to identify peripheral stations.
W. Percentage of winter 2315 GMT soundings with an elevated inver-
sion base within 3000 m AGL (left) and a thickness exceeding
100, 250, 500, 750, 1000, or 1500 m (right, bottom to top).
Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
47. Percentage of spring 2315 GMT soundings with an elevated inver-
sion base within 3000 m AGL (left) and a thickness exceeding
100, 250, 500, 750, 1000, or 1500 m (right, bottom to top).
Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
48. Percentage of summer 2315 GUT soundings with an elevated inver-
sion base within 3000 m AGL (left) and a thickness exceeding
100, 250, 500, 750, 1000, or 1500 m (right, bottom to top).
Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
71
72
73
74
75
76
77
78
49. Percentage of autumn 2315 GMT soundings with an elevated inver-
sion base within 3000 m AGL (left) and a thickness exceeding
100, 250, 500, 750, 100C, or 1500 m (right, bottom to top).
Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
50. Percentage of winter 1115 GMT soundings with a surface-based
inversion and a thickness of 500 m or less (left) or greater
than 500 m (right) with a AT/AH of 0-0.47, 0.48-1.14, l.lb-2.82,
2.83-6.00, or >6.0 "C/100 m (botton to top). Isopleths are for
a thickness of 500 m or less and a AT/AH of 1.15-2.82 °C/1QO m.
See Figure 2 to identify peripheral stations.
51. Percentage of spring 1115 GMT soundings with a surface-based
inversion and a thickness of 500 n or less (left) or greater
than 500 m (right) with a AT/AH of 0-0.47, 0.48-1.14, 1.15-2.82,
2.83-b.OU, or >fa.U "I/ODD m (bottom to top). Isopleths are for
a thickness of 500 m or less and a AT/AH of 1.15-2.82 °C/100 m.
See Figure 2 to identify peripheral stations.
52. Percentage of summer 1115 GMT soundings with a surface-based
inversion and a thickness of 500 m or less (left) or greater
than 500 m (right) with a AT/AH of 0-0.47, 0.48-1.14, 1.15-2.82,
2.83-6.00, or >6.0 "C/100 m (bottom to top). Isopleths are for
a thickness of 500 m or less and a AT/AH of 1.15-2.32 °C/100 m.
See Figure 2 to identify peripheral stations.
53. Percentage of autumn 1115 GMT soundings with a surface-based
inversion and a thickness cf 500 m or less (left) or greater
than 500 m (right) with a AT/AH of 0-0.47, 0.48-1.14, 1.15-2.82,
2.83-6.00, or>6,0 "C/100 m (bottom to top). Isopleths are for
a thickness of 500 m or less and a AT/AH of 1.15-2.82 °C/100 m.
See Figure 2 to identify peripheral stations.
54. Percentage of all 2315 GMT soundings with a surface-based
inversion and a thickness of 500 m or less (left) or greater
than 500 m (right) with a AT/AH of 0-0.47, 0.48-1.14, 1.15-2.82,
2.83-6.00, or>6.0 °C/100 m (bottom to top). Isopleths are for
a thickness of 500 m or less and a AT/AH of 1.15-2.82 "C/100 m.
See Figure 2 to identify peripheral stations.
55. Percentage of all 1115 GMT soundings with an elevated inversion
t.ase within 3000 m AGL and a thickness of 500 m or less
(left) or greater than 500 m (right) with a AT/AH of 0-0.47,
0.48-1.14, 1.15-2.82, 2.83-6.00, or >6.0 °C/100 m (bottom
to top). Isopleths are for a thickness of 500 m or less and a
AT/AH of 0.48-1.14 °C/100 m. See Figure 2 to identify the
peripheral stations.
79
80
81
82
83
84
85
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Number
Page
56. Percentage of winter 2315 GMT soundings with an elevated inver-
sion base within 3000 m AGL and a thickness of 500 m or less
(left) or greater than 500 m (right) with a AT/AH of 0-0.47,
0.48-1.14, 1.15-2.82, 2.83-6.CO, or >6.0 °C/|00 m (bottom
to top). Isopleths are for a thickness of 500 m or less and a
AT/AH of 0.48-1.14 "C/100 m. See Figure 2 to identify the
peripheral stations. 86
57. Percentage of spring 2315 GMT soundings with an elevated inver-
sion base within 30CO m AGL and a thickness of 500 m or less
(left) or greater than 500 m (right) with a AT/AH of 0-0.47,
0.48-1.14, 1.15-2.82, 2.83-6.00, or >6.0 "C/100 m (bottom
to top). Isopleths are for a thickness of 500 m or less and a
AT/AK of 0.48-1.14 °C/100 m. See Figure 2 to identify the
peripheral stations. 87
58. Percentage of summer 2315 SMT soundings with an elevated inver-
sion base within 3000 m AGU and a thickness of 500 m or less
(left) or greater than 500 m (right) with a AT/AH of 0-0.47,
0.48-1.14, 1.15-2.82, 2.83-6.00, or >6.0 "C/10Q m (bottom
to top). Isopleths are for a thickness of 500 m or less and a
AT/AH of 0.48-1.14 °C/100 m. See Figure 2 to identify the
peripheral stations. 88
59. Percentage of autumn 2315 GMT soundings with an elevated inver-
sion base within 3000 is AGL and a thickness of 500 m or less
(left) or greater than 500 m (right) with a AT/AH of 0-0.47,
0.48-1.14, 1.15-2.a2, 2.83-6.00, or >6.0 "C/100 m (bottom
to top). Isopleths are for a thickness of 500 m or less and a
AT/AH of 0.18-1.14 °C/100 m. See Figure 2 to identify the
peripheral stations. 89
60. Percentage of winter 2315 GMT soundings with no inversion below
3000 m AGL (left) and with a decreasing temperature with height
(-tT/AH) greater than 1.2 "C/100 m in the layers 1-100,
101-250, 251-500, 501-750, 751-1000, or 1001-1500 m AGL (right,
bottom to top). See Figure 2 to identify the peripheral
stations. 90
61. Percentage of spring 2315 GMT soundings with no inversion below
3000 m AGL (left) and with a decreasing temperature with height
(-AT/AH) greater than 1.2 °C/1UO m in the layers 1-100,
101-250, 251-500, 501-750, 751-100C, or 1001-1500 m AGL (right,
bottom to top). See Figure 2 to identify the peripheral
stations. 91
Number
Page
62. Percentage of summer 2315 GMT soundings with no inversion below
3000 m AGL (left) and with a decreasing temperature with height
(-AT/AH) greater than 1.2 °C/100 m in the layers 1-100,
101-250, 251-500, 501-750, 751-1000, or 1001-1500 m AGL (right,
bottom to top). See Figure 2 to identify the peripheral
stations.
63. Percentage of autumn 2315 GMT soundings with no inversion below
3000 m AGL (left) and with a decreasing temperature with height
(-AT/AH) greater than 1.2 °C/100 m in the layers 1-100,
101-250, 251-500, 501-750, 751-1000, or 1001-1500 m AGL (right,
bottom to top). See Figure 2 to identify the peripheral
stations.
64. Percentage of summer 2315 GMT soundings with no inversion below
3000 m AGL (left) and with a temperature decrease with height
(-AT/AH) greater than 0.8 °C/100 m in the layers 1-100,
101-250, 251-500, 501-750, 751-1000, or 1001-1500 m AGL (right,
bottom to top). See Figure 2 to identify the peripheral
stations.
65. Percentage of winter 2315 GMT soundings with an elevated inver-
sion base in the layer 1-100, 101-250, 251-500, 501-750,
751-1000, 1001-2000, or 2001-3000 m AGL (left, bottom to top),
and a temperature decrease with height (-AT/AH) greater than
1.2 °C/100 m in the layer below (right, bottom to top). See
Figure 2 to identify the peripheral stations.
66. Percentage of spring 2315 GMT soundings with an elevated inver-
sion base in the layer 1-100, 101-250, 251-500, 501-750,
751-1000, 1001-2000, or 2001-3000 m AGL (left, bottom to top),
and a temperature decrease with height (-AT/AH) greater than
1.2 °C/100 m in the layer below (right, bottom to top). See
Figure 2 to identify the peripheral stations.
67. Percentage of summer 2315 GMT soundings with an elevated inver-
sion base in the layer 1-100, 101-250, 251-500, 501-750,
751-1000, 1001-2000, or 2001-3000 m AGL (left, bottom to top),
and a temperature decrease with height (-AT/AH) greater than
1.2 °C/100 m in the layer below (right, bottom to top). See
Figure 2 to identify the peripheral stations.
68. Percentage of autumn 2315 GMT soundings with an elevated inver-
sion base in the layer 1-100, 101-250, 251-500, 501-750,
751-1000, 1001-2000, or 2001-3000 m AGL (left, bottom to top),
and a temperature decrease with height (-AT/AH) greater than
1.2 °C/100 m in the layer below (right, bottom to top). See
Figure 2 to identify the peripheral stations.
92
93
94
95
96
97
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Number
69. Percentage of winter 1115 GMT soundings with a surface-based
inversion and an average relative humidity in the inversion
(bottom) and in the 300-m layer above the inversion top (top) of
>69% (left) and >89% (right). Isopleths are for surface-based
inversions in which the average relative humidity is >69%. See
Figure 2 to ioentify the peripheral stations.
70. Percentage of spring 1115 GMT soundings with a surface-based
inversion and an average relative humidity in the inversion
(bottom) and in the 300-m layer above the inversion top (top) of
>69% (left) and >B9% (right). Isopleths are for surface-based
inversions in which the average relative humidity is >69%- See
Figure 2 to identify the peripheral stations.
71. Percentage of summer 1115 GMT soundings with a surface-based
inversion and an average relative humidity in the inversion
(bottom) and in the 30Q-m layer above the inversion top (top) of
>69% (left) and >89» (right). Isopleths are for surface-based
inversions in which the average relative humidity is >&9%. See
Figure 2 to identify the peripheral stations.
72. Percentage of autumn 1115 GMT soundings with a surface-based
inversion and an average relative humidity in the inversion
(bottom) and in the 300-m layer above the inversion top (top) of
>69I (left) and >89% (right). Isopleths are for surface-based
inversions in which the average relative humidity is >69%. See
Figure 2 to identify the peripheral stations.
73. Percentage of all 2315 soundings with a surface-based
inversion and an average relative humidity in the inversion
(bottom) and in the 300-m layer above the inversion top (top) of
>692 (left) and >89% (right). Isopleths are for surface-based
inversions in which the average relative humidity is >69%. See
Figure 2 to identify the peripheral stations.
74. Percentage of winter 1115 GMT soundings with an elevated inver-
sion based within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in
the inversion (top) of >69% (left) and >89% (right). Isopleths
are for elevated inversions below which the average relative
humidity is >69%. See Figure 2 to identify the peripheral
stations.
75. Percentage of spring 1115 GMT soundings with an elevated inver-
sion based within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in
the inversion (top) of >69% (left) and >89% (right). Isopleths
are for elevated inversions below which the average relative
humidity is >69%. See Figure 2 to identify the peripheral
stations.
Page
99
100
101
102
103
Number
76.
Page
104
105
Percentage of summer 1115 GMT soundings with an elevated inver-
sion based within 3000 m AGL and an average relative huipidity
in the entire layer below the inversion base (bottom) anc in
the inversion (top) of >69% (left) and >B9% (right). Isopleths
are for elevated inversions below which the average relative
humidity is >69%. See Figure 2 to iaentify the peripheral
stations.
77. Percentage of autumn 1115 GMT soundings with an elevated inver-
sion based within 300C m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in
the inversion (top) of >69S! (left) and >89% (right). Isopleths
are for elevated inversions below which the average relative
humidity is >69%. See Figure 2 to identify the peripheral
stations.
78. Percentage of winter 2315 GMT soundings with an elevated inver-
sion based within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in
the inversion (top) of >(,9% (left) and >89% (right). Isopleths
are for elevatec inversions below which the average relative
humidity is >69%. See Figure 2 to identify the peripheral
stations.
79. Percentage of spring 2315 GMT soundings with an elevated inver-
sion based within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in
the inversion (top) of >69% (left) and >89% (right). Isopleths
are for elevated inversions below which the average relative
humidity is >69%. See Figure 2 to identify the peripheral
stations.
80. Percentage of summer 2315 GMT soundings nith an elevated inver-
sion based within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) ano in
the inversion (top) of >69% (left) and >&9% (right). Isopleths
are for elevated inversions below which the average relative
humidity is >69$. See Figure 2 to identify the peripheral
stations.
81. Percentage of autumn 2315 GMT soundings with an elevated inver-
sion based within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in
the inversion (top) of >£9u (left) and >S9% (right). Isopleths
are for elevated inversions below which the average relative
humidity is >69X. See Figure 2 to identify the peripheral
stations.
106
107
108
109
110
111
-------
Number
Page
82. Percentage of winter 1115 GMT soundings with no inversion below
3000 m AGL and an average relative humidity >69% (left) and
>89% (right) in the layers 1-100, 101-250, 251-500, 501-750,
751-1000, and 1001-1500 m AGL (bottom to top). Isopleths are
for an average relative humidity >69* in the layer 251-500 m AGL.
See Figure 2 to identify the peripheral stations. 112
83. Percentage of spring 1115 GMT soundings with no inversion below
3000 m AGL and an average relative humidity >69% (left) and
>89% (right) in the layers 1-100, 101-250, 251-500, 501-750,
751-1000, and 1001-1500 m AGL (bottom to top). Isopleths are
for an average relative humidity >693£ in the layer 251-500 m AGL.
See Figure 2 to identify the peripheral stations. 113
84. Percentage of summer 1115 GMT soundings with no inversion below
3000 m AGL and an average relative humidity >C9% (left) and
>89% (right) in the layers 1-100, 101-250, 251-500, 501-750,
751-1000, and 1001-1500 m AGL (bottom to top). Isopleths are
for an average relative humidity >69? in the layer 251-500 n AGL.
See Figure 2 to idertify peripheral stations. 114
85. Percentage of autumn 1115 GMT soundings with ro inversion below
300C in AGL and an average relative humidity >69% (left) and
>89% (right) in the layers 1-100, 101-250, 251-500, 501-750,
751-1000, and 1001-1500 m AGL (bottom to top). Isopleths are
for an average relative humidity >69" in the layer 251-500 m AGL.
See Figure 2 to identify peripheral stations. 115
86. Percentage of winter Z^IE GrTT soundings with no inversion below
300C m AGL and an average relative humidity >69? (left) and
>89% (right) in the layers 1-1CO, 101-250, 251-500, 501-750,
751-1000, and 1001-1500 m AGL (bottom to top). Isopleths are
for an average relative hurridity >69% in the layer 251-500 m AGL.
See Figure 2 to identify peripheral stations. 116
87. Percentage of spring 2315 GMT soundings with no inversion below
300C m AGL and an average relative huiridity >G9" (left) and
>89S (right) in the layers 1-ino, 101-250, 251-500, 501-750,
751-1000, and 1001-1500 m AGL (bottom to top). Isopleths are
for an average relative humidity >6S" in the layer 251-500 w, AGL.
See Fioure 2 to idertify peripheral stations. 117
88. Percentage cf summer 2315 GI'T soundings with re inversion below
30CC n AGL and an average relative huir-icity >f9" (left) and
>89? (right) in the layers 1-100, !Cl-?5n, 251-500, 501-750,
751-1000, and 1001-1500 n AGL (bottom to top). Isopleths are
for an average relative huridity >69/' in the layer 251-500 m AGL.
See Figure 2 to identify peripheral stations. 118
Number
Page
Percentage of autumn 2315 GMT soundings with no inversion below
3000 m AGL and an average relative humidity >69% (left) and
>89? (right) in the layers 1-100, 101-250, 251-500, 501-750,
751-1000, and 1001-1500 m AGL (bottom to top). Isopleths are
for an average relative humidity >69% in the layer 251-500 m AGL.
See Figure 2 to identify peripheral stations. 119
90. Percentage of winter 1115 GMT soundings with an inversion base
at the surface and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0,
and >10.0 m/s (bottom to top). See Figure 2 to identify
peripheral stations.
91. Percentage of spring 1115 GMT soundings with an inversion base
at the surface and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0,
and >10.0 m/s (bottom to top). See Figure 2 to identify
peripheral stations. 121
92. Percentage of summer 1115 GMT soundings with an inversion base
at the surface and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0,
and >10.0 m/s (bottom to top). See Figure 2 to identify
peripheral stations. 122
53. Percentage of autumn 1115 GMT soundings with an inversion base
at the surface and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0,
and >10.0 m/s (bottom to top). See Figure 2 to identify
peripheral stations. 123
94. Percentage of winter 2315 GMT soundings with an inversion base
at the surface and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0,
and >10.0 m/s (bottom to top). See Figure 2 to identify
peripheral stations. 124
95. Percentage of spring 2315 GMT soundings with an inversion base
at the surface and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0,
and >10.0 m/s (bottom to top). See Figure 2 to identify
peripheral stations. 125
96. Percentage of summer 2315 GMT soundings with an inversion base
at the surface and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0,
and >10.0 m/s (bottom to top). See Figure 2 to identify
peripheral stations. 126
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Number
Page
Number
Page
97. Percentage of autumn 2315 GMT soundings with an Inversion base
at the surface and wind speeds at the surface (left) and at
300 m A6L (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0,
and >10.0 m/s (bottom to top). See Figure 2 to identify
peripheral stations.
98. Percentage of winter 1115 GMT soundings with an elevated inver-
sion base 1-3000 m AGL and wind speeds at the surrace (left)
and at 300 m AGL (right) in the ranges calm, 0.1-2.5, Z.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
99. Percentage of spring 1115 GMT soundings with an elevated inver-
sion base 1-3000 m AGL and wind speeds at tne surface umj
and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
100. Percentage of summer 1115 GMT soundings with an elevated inver-
sion base 1-3000 m AGL and wind speeds at tne surface fleft)
and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0,
5.1-10.0, and ?10,0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
101. Percentage of autumn 1115 GMT soundings with an elevated inver-
sion base 1-3000 m AGL and wind speeds at the surface (left)
and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
102. Percentage of winter 2315 GMT soundings with an elevated inver-
sion base 1-3000 m AGL and wind speeds at the surface (left)
and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
103. Percentage of spring 2315 GMT soundings with an elevated inver-
sion base 1-3000 m AGL and wind speeds at the surface (left)
and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
127
128
129
130
131
132
133
104.
105.
Percentage of summer 2315 GKT soundings with an elevated inver-
sion base 1-3000 m AGL and wind speeds at the surface (left)
arc! at 300 m AGL (right) in the ranges caln, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure Z to
identify the peripheral stations.
134
106.
Percentage of autumn 2315 GMT soundings with an elevated inver-
sion base 1-3000 m AGL and wind speeds at the surface (left)
and at 300 m AGL (right) in the ranges call?, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations. 135
Percentage of all 1115 GMT soundings with no inversion below
3000 m AGL and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations. 136
1C7. Percentage of winter 2315 GMT soundings v10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations. 137
108. Percentage of spring 2315 GMT soundings with no inversion belc*
3COO m AGL and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations. 138
109. Percentage of summer 2315 GMT soundings with no inversion below
3000 m AGL and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations. 139
110. Percentage of autumn 2315 GMT soundings with no inversion below
3000 m AGL and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges caln, 0.1-2.5, 2.6-5.0,
5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations. 1*0
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SECTION 1
INTRODUCTION
In analyzing environmental impacts of air
pollutants the transport and diffusion properties
of the atmosphere are always of utmost importance;
in many cases transformation and/or removal
processes are equally important. For incorpora-
ting these processes into impact evaluations the
available meteorological information is seldom
optimum, even in designed experiments. In
actual situations analysts rely heavily for data
upon the hourly surface-based observations taken
at many airports by the National Weather Service
(NWS) or by the Federal Aviation Administration. A
shortcoming in using these data is that in some
situations they are not representative of impor-
tant processes above the near-ground layer.
This difficulty is offset somewhat by the NWS
upper-air sounding program. Although these
measurements are taken only at 12-hourly intervals
at stations spaced on the order of 300 km, the
vertical dimension of measurement is invaluable.
The objective of this report is to present
summaries of the lower few kilometers of upper
air data that may be important in evaluating
environmental impacts of air pollutants.
The NWS upper-air sounding program employs
rawinsondes to determine vertical profiles of
pressure, temperature, humidity, and wind. One
of the rawinsonde-measured variables that is
often studied is temperature structure, especially
temperature inversions because of their marked
inhibiting effects on vertical motion. The
frequency of ground-based or very low-level
inversions has been determined for the contiguous
United States by Hosier (1961) and for Canada by
Munn et al . (1970). But there is considerable
additional useful dispersion information to be
extracted from the rawinsonde observations; for
example, characterization of elevated inversions,
inversion thicknesses, and temperature structure
in the absence of inversions, as was done to
some extent by Bilello (1966) for some Arctic
stations. In addition, data on winds aloft are
important in pollutant transport, while moisture
content is pertinent to the atmospheric trans-
formation of certain pollutants as well as in
evaluating the impact of cooling towers. Although
certain of these variables (some of which have
been determined from sources other than rawinsondes,
e.g., towers) can be found in local studies of
environmental impact, comprehensive national
summaries are rare. The data in this report are
for the United States, including stations in
Alaska, Hawaii, and Puerto Rico.
The rawinsonde is a balloon-borne, shoe
box-size package containing miniaturized in-
struments that measure and semi-continuously
radio the pressure, temperature, and humidity to
a ground station where the balloon is simul-
taneously tracked by a radio direction finder in
order to compute the wind speed and direction.
In the lower troposphere the balloons rise at a
rate of 5 m/sec. The temperature sensor has a
lag of no more than 6 sec at pressures greater
than 700 mb, (i.e., at heights below 3 km where
our interest lies for sea level locations). At
several western stations where the elevation is
1500 m or more, soundings to 3000 m above the
surface result in pressures as low as 500 mb.
However, the additional estimated instrument lag
will not significantly affect comparisons with
lower elevation stations (Ference, 1951; Badgley,
1957), The 6-sec lag means that in the lower
troposphere the sensor detects 63 percent of an
instantaneous temperature change in no more than
about 30 m. Considering all reasonable possi-
bilities, the over-all probable error in rawin-
sonde temperatures is about + 0.5°C (Ference,
1951). In reporting these sounding data, small
details are omitted. The NWS assumes that the
temperature varies linearly between adjacent
levels, but sufficient levels are required so
that no temperature on the actual sounding
deviates by 1°C or more from the reported sound-
ing. Although the overall probable error in
pressure measurements is estimated to be no more
than + 2 mb up to the 700-mb level (about 3 km
above mean sea level), the incremental probable
error between successive pressure measurements
is believed to be +_ 0.5 mb (Ference, 1951). The
least accurate rawinsonde measurement is relative
humidity; its accuracy is difficult to define
because of the complex nature of contributing
factors. However, if the sensor is not sub-
jected to condensations, the relative humidity
probable error is estimated to be +_ 2.5 percent
for temperatures to -10°C and a humidity range
of 15 to 96 percent (Ference, 1951). The rela-
tive humidity data presented in this report have
been averaged over various layers. The accuracy
of rawinsonde winds is also very difficult to
evaluate because of the number of factors
involved, their range of values, and possible
-------
combinations. An obvious important factor is
the accuracy of the azimuth and elevation angles;
the overall probable error is estimated to be
+ 0.05 degree with elevation angles above
6 degrees (Ference, 1951). At lower angles the
tracking accuracy deteriorates rapidly because
of ground reflections. For our interest in the
lower few kilometers the wind errors are not
believed to be significant. The surface wind
measurement is taken directly from an anemometer.
Rawinsonde observations are scheduled
internationally for 0000 and 1200 GMT daily to
determine the atmospheric structure at levels
well up into the stratosphere. We are, of
course, interested in the lowest few kilometers
of the soundings. That the soundings are taken
only twice daily is a shortcoming for our pur-
poses because of the typical large diurnal
variation that occurs in the near boundary
layer. However, it is fortunate that in much of
the United States the 1200 and 0000 GMT local
sounding times are close to the usual times of
greatest stability (near sunrise) and insta-
bility (mid-afternoon), respectively. On the
other hand, some subtle but distinct advantages
of rawinsonde data are that they extend through
the layers of interest, they were taken uniformly
at widely distributed locations, and the data
are readily available.
SECTION 2
DATA PROCESSING
In order to properly interpret the data in
this report it is necessary to understand the
processing details. The processing occurred in
two steps. First, each sounding was analyzed to
extract and archive the desired information.
Then the extracted data were summarized in a
climatological format by observation time,
season, and station. A third step consisted of
machine plotting certain of the summarized
variables on maps for analyses. Since the
archived records of each rawinsonde observation
include far more information than required for
the purposes of this report, each sounding was
analyzed to retain only pertinent data.
TEMPERATURE
In processing the temperature data, no more
than one temperature inversion was specified for
each sounding. Isothermal layers were treated
as inversions. For soundings with complicated
or multiple inversions an arbitrary definition
was used to simplify them. The processed inver-
sion base was the lowest inversion base within
3000 m of the surface (all heights are with
respect to surface elevation unless stated
otherwise). The processed inversion top was
that inversion top with the maximum actual
temperature within 4500 m of the surface.
Examples of this processing scheme are shown in
Figure 1.
For soundings with no inversion within the
lower 3000 m, values of AT/AZ were determined
for the layers 1-100, 101-250, 251-500, 501-750,
751-1000, and 1001-1500 m. The required tempera-
tures at specified heights were determined by
simple interpolation between the significant
points of each rawinsonde observation.
RELATIVE HUMIDITY
Relative humidity was processed to give
average values for the inversion layer, the
subinversion layer in the case of elevated
inversions, and the 300-m layer above the top of
ground-based inversions; for no-inversion
soundings the average relative humidity was for
the same layers as for AT/AZ (above). In deter-
mining layer averages of relative humidity, the
values at the bottom and top of a specified
layer were obtained by simple interpolaton
between the nearest significant points. Where
additional humidity values were given within a
specified layer, that layer was broken into
sublayers; the average for a sublayer was the
average of the humidity values at the bottom and
top of the sublayer. The average for the entire
specified layer was determined from the sublayer
averages, weighted for their thickness with
respect to that of the specified layer.
WINDS
Wind direction and speed were processed to
give values at ground level and 150, 3CO, 600,
900, and 1200 m above ground level (AGL). These
heights were usually different from those of the
archived sounding data (surface, 150, and 300 m
AGL; 500, 1000, 1500, etc., msl; and at standard
pressure levels of 1000, 950, 900, 850, etc.,
mt>). The processed wind values were obtained
-------
by interpolation; details are given by the
National Climatic Center in their summaries for
individual stations (see Appendix A).
The pertinent data on temperature, relative
humidity, and wind that were determined for each
sounding were used to generate various other
variables (e.g., inversion thickness, tempera-
ture increase with height, etc.) that were also
stored on magnetic tape. These data were summarized
into climatological formats, and are selectively
used in this report. APPENDIX A describes these
formats and their availability. APPENDIX A also
lists the stations and periods for which summaries
have been prepared.
SECTION 3
GENERAL DISCUSSION
Figure 2 identifies all of the stations for
which data are presented in this report. The
two Hawaiian stations, seven Alaskan, and San
Juan, Puerto Rico are plotted along the peri-
phery of the map. San Diego is plotted immediately
below southern California to avoid overprinting
of the Santa Monica data.
For most stations the period of record
summarized is the 5 years, 1960 through 1964,
with exceptions indicated on Figure 2 and in
Table A-6. The only station with all summarized
soundings outside the period 1960-1964 is Wallops
Island, Virginia. These years were selected to
coincide with those used earlier in climatological
estimates of mixing heights (Holzworth, 1972).
The extent to which the data for 1960-1964 are
sufficiently representative is open to debate.
However, participants at a recent conference on
air quality modeling guidelines (Roberts, 1977)
generally concluded that for their purposes a
5-year record was adequate.
While the routine rawinsondes were released
at the same Greenwich Mean Time (GMT) every day,
the angle of the sun with the horizon, of
course, varied from day-to-day throughout the
year. Climatically, the effect of variable
solar surface heating results in significant
seasonal variations in the thermal structure of
the lower atmosphere. To demonstrate the pos-
sibility of this effect, the solar elevation
angle for the middle day of each meteorological
season (i.e., January 15, April 15, July 15, and
October 15) at the customary rawinsonde release
times (i.e., 1115 and 2315 GMT) are presented in
Figures 3 - 10. Notice that on January 15 at
1115 GMT (Figure 3) the only station where the
sun is above the horizon is San Juan, but even
there only the beginning of surface heating is
expected. On the other hand, in the West and
North, sunrise is hours or more away and the
full effect of long-wave radiational cooling
has not yet been realized. On January 15 at
2315 GMT (Figure 7) the sun is near the horizon
through the middle of the 48 states so that
long-wave cooling is well under way over the
northeastern states, has barely begun along the
Pacific Coast, and hasn't even started in Hawaii.
On July 15 at 1115 GMT (Figure 5) solar
heatirj has begun in the northeastern states,
but is still hours away in the western states,
except Alaska. North of the Arctic Circle the
sun remains above the horizon on some summer
days, but nevertheless marked diurnal variations
can occur in the temperature structure near the
ground. On July 15 at 2315 GMT (Figure 9) the
sun is above the horizon at every station,
except San Juan. Long-wave cooling is about to
begin along the Atlantic seaboard, but through-
out much of the West maximum temperatures for
the day are just about to be reached. Solar
elevations on October 15 at 2315 GMT are shown
in Figure 10.
Since the possible number of rawinsonde-
derived variables and combinations thereof is
very large, only the more important ones were
selected for presentation in this report. Even
so, there are 100 data maps. They fall into
three main groups, depicting the characteristics
of (1) vertical temperature structure (2) rela-
tive humidity for certain configurations of
temperature structure, and (3) wind speeds for
certain configurations of temperature structure.
In order to present as much potentially useful
information as possible some maps include up to
14 pieces of data for each station. However, no
more than one set of isopleths appears on each
map; on some maps no isopleths are presented.
The variables that were selected for analyses
were chosen to illustrate the general patterns
of the data, but are not necessarily indicative
of isopleth analyses for other variables on the
same maps. Furthermore, the isopleths should be
used cautiously, especially in non-uniform and
irregular terrain where values for particular
variables may change significantly over short
distances. In this regard, it should be pointed
-------
out that in areas of irregular terrain most
rawinsonde stations are located in valleys; none
are located on mountain peaks or ridges where
the climate is typically very different from
that of nearby valleys. In addition, most
rawinsonde stations are located in suburban or
rural areas and seldom show marked effects of
densely built-up areas. Except where urban
effects do show up explicitly in the data, no
attempts have been made to incorporate urban
effects into the isopleth analyses. Attempts to
infer data values at locations beyond the
rawinsonde sites should only be done with great
care and with knowledge of the climate in the
surrounding area.
In general, there is so much information on
the charts presented in this report that it is
difficult to pick out all of the potentially
important features, let alone comment on them.
Rather, only limited discussions are presented,
leaving further interpretations to the reader.
In such considerations it is well to keep in
mind that the individual variables and their
values are only parts of a completely internally
consistent set of data.
All of the climatic data on Figures 11 - 110
are in percentage values rounded to the nearest
whole number, and are with respect to the total
number of observations. For practical purposes
missing observations were zero at all stations.
In this report the seasons are defined as
December + January + February = Winter, March +
April + May = Spring, etc.
CHARACTERISTICS OF VERTICAL TEMPERATURE STRUCTURE
AJ1 Inversions
Most of the data in this report are concerned
with describing the vertical temperature structure
of the lower atmosphere. The first group of
maps gives the percentages of all soundings with
at least one inversion (i.e., surface-based or
elevated) within 3 km of the surface. For
1115 GMT the data are only presented annually
(Figure 11) since seasonal variations are slight.
From Figure 11 it is clear that morning soundings
without an inversion are uncommon. Even in
tropical San Ouan inversions occur in 69 percent
of the observations. The lowest frequency in
the contiguous 48 states is just under 70 percent
at Tatoosh Island; the lowest at any station is
57 percent at nearby Annette, Alaska. These
relatively low frequencies are attributed to the
common occurrence of storms along this part of
the Pacific Coast. Undoubtedly, the major
reason for the high frequency of inversions at
1115 GMT is that even during the summer the sun
is only slightly above the horizon over about
half of the United States (see Figures 3 - 6),
thus limiting solar heating.
At 2315 GMT the seasonal variation of all
inversions (Figures 12 - 15) is considerably
greater than at 1115 GMT. In general, for the
contiguous 48 states the occurrence of all
inversions at 2315 GMT is greatest in winter
(Figure 12), least in summer (Figure 14), and
intermediate during the transition seasons
(Figures 13 and 15). In winter the frequencies
exceed 70-80 percent everywhere east of the
Rockies, including San Juan, and along the
Oregon-California coastal regions. Even over
the Rockies the frequencies exceed 50 percent,
except in the extreme south. The relatively low
winter occurrences, around 60 percent, over
Washington extend north along the Pacific Coast
through Annette (50 percent) and Yakutat
(62 percent), but then increase to 94 percent at
Anchorage. Although Anchorage is a major sea-
port, it lies at the upper end of Cook Inlet and
is rather well sheltered by mountains from the
storms that are common throughout the nearby
ocean.
For most stations the lowest occurrence of
all inversions at 2315 GMT is during summer
(Figure 14). Over much of the Rockies the
frequencies are less than 30-40 percent, ranging
down to only a few percent. This dearth of
inversions within 3 km of the surface is due to
the high solar elevation at 2315 GMT (Figure 9),
the high altitude of the terrain, and aridity of
the region, all of which enhance the transfer of
solar radiation to the surface where it heats
the ground, which heats the air. Along the
California-Oregon-Washington Coast and along the
northern Atlantic Coast the frequencies of all
inversions at 2315 GMT show only slight seasonal
variations. However, along the California Coast
the highest frequencies, nearly 100 percent,
occur in summer, reflecting the well-known
subsidence or marine inversion that prevails in
summer. Along the immediate coast of the
northern Atlantic the summer frequencies are
only slightly less than in winter, but unlike
winter they drop off rapidly to the west.
-------
The relatively high frequencies of about 50 per-
cent over the upper Midwest (Figure 14) are inter-
esting because a physical explanation for their
occurrence is not understood. The large frequen-
cies in Hawaii, even with high sun, are caused by
the trade-wind inversion, which is negligibly
affected by surface heating over the ocean. The
low frequencies north along the Alaskan Coast,
Annette to Yakutat to Anchorage, apparently do
reflect the effects of large heating at the sur-
face and a high sun at observation time. This
effect among Alaskan stations culminates at Fair-
banks which has an inversion within 3 km of the
surface in only 24 percent of the summer afternoon
soundings. The comparatively high frequencies of
inversions at Nome, Barrow, and Barter on the
immediate coast of Alaska are attributed to ice-
covered or very cold adjacent waters and frozen
ground. Generally, the frequency of all inversions
is greater in autumn (Figure 15) than in summer,
following the seasonal solar cycle.
Surface-Based Inversions
Figures 16 - 19 show the 1115 GMT seasonal
distributions of surface-based inversions. Since
at this time the sun is above the horizon only
over the eastern half of the contiguous 48 states,
it is not surprising that surface-based inver-
sions are common throughout the year. Frequen-
cies exceeding 90 percent occur over the Rockies
in all seasons, but are most abundant in summer
and autumn (Figures 18 and 19). Ground- (or
surface-) based inversions in the morning are
also generally common throughout the year
over the southern Appalachians and coastal
Piedmont with frequencies of around 60-70 percent.
There is an interesting secondary maximum of
morning surface inversions over the central
Midwest in summer (Figure 18). These high
values extend southward to Lake Charles with a
frequency of 94 percent, which contrasts sharply
with values of only 15 and 21 percent at nearby
San Antonio and Burwood. Notice that this
curious pattern is also apparent in spring and
autumn (Figures 17 and 19). The reason for such
large variations over relatively short distances
is not understood (the summaries have been
double-checked), but the patterns compare favor-
ably with data presented by Hosier (1961).
Areas with relatively few ground-based
inversions throughout the year are centered
along the Washington Coast and in the vicinity
of New York City (i,e., in the soundings from
J. F. Kennedy Airport). The former are readily
attributed to the occurrence of dense clouds and
fast winds associated with storms, while the
latter is thought to reflect effects of intense
human activity (e.g., the urban heat island),
perhaps augmented by the distribution of water
temperatures in the vicinity of New York City.
Another interesting feature of ground-based
inversions in Figures 16 - 19 is the variation
along the California Coast from around 70 percent
in winter to less than 20 percent in summer.
This is caused, of course, by the predominance
of the well-known (elevated) subsidence or
marine inversion during summer (Neiburger et al,
1961). The low frequency of ground inversions
in the vicinity of the Great Lakes during winter
reflects the effects of cold Canadian air stream-
ing southward over the relatively warm lakes,
which generate dense low clouds and frequent
snow flurries.
The occurrence of surface-based inversions
in the morning at San Juan varies from 70 percent
in winter to 22 percent in summer, as expected
from the variation in solar elevation at obser-
vation time (1115 GMT). The same sort of
seasonal variation also occurs at Lihue, although
the actual frequencies are generally somewhat
less, ranging from 46 percent to 22 percent.
Compared to San Juan, these fewer occurrences
are due to the shorter duration of long-wave
cooling since late afternoon/early evening.
Such cooling is more effective at higher eleva-
tions, especially in the tropics, and manifests
itself at lower elevations by cool drainage
flows. This effect shows up very markedly at
Hilo on Hawaii Island, not far from Lihue on
Kauai Island. Hilo is near the base of Mauna
Loa (4171 m above sea level) and has seasonal
frequencies of morning ground-based inversions
that are surprisingly high, but vary only rela-
tively slightly, between 90 and 78 percent. At
the Alaskan stations the highest frequencies of
morning ground-based inversions generally occur
in winter and the lowest in summer, largely as a
consequence of the solar cycle. However, there
are clearly regional differences that reflect
the local climate.
Figures 20 - 23 show the seasonal frequen-
cies of surface-based inversions at 2315 GMT.
At this observation time the local time varies
from mid-afternoon in summer along the Pacific
Coast of the contiguous 48 states to post-sunset
5
-------
In winter over the eastern states (see Figures 7 -
10). The general effects of such variations can
be seen in the distributions of surface-based
inversions, although there are also clear indi-
cations of local climate effects. At 2315 GMT
surface-based inversions are most extensive over
the contiguous 48 states during winter (Figure 20).
Only in the southwestern region and southern
Florida are the frequencies less than 10 percent;.
they exceed 50 percent only along and near the
Atlantic Coast. Again, the data suggest effects
of anomalous heating in the vicinity of New York
City. The isopleth patterns for spring and
summer (Figures 21 and 22) are very similar with
significant occurrences of surface-based inver-
sions only in the vicinity of the Atlantic
Coast. The autumn (Figure 23) distribution of
evening ground-based inversions is clearly
intermediate between those of summer and winter,
and largely demonstrates the effects of enhanced
long-wave cooling as the sun sets earlier.
At San Juan the seasonal frequencies of
ground-based inversions at 2315 GMT follow those
at Miami rather closely. The frequencies at the
two Hawaiian stations are in very close agree-
ment with those along the California Coast. The
Alaskan stations generally show ground-based
inversion frequencies increasing with latitude
in all seasons but, as expected for most stations,
the highest frequencies occur in winter and the
lowest in summer.
Elevated Inversions
Since the frequency of all inversions
(i.e., elevated plus qround-based) at 1115 GMT
has been shown (Figure 11) to be uniformly high
(i.e., exceeding 80-90 percent at almost all
stations), those regions with high frequencies
of ground-based inversions must have low fre-
quencies of elevated inversions and vice versa.
Thus, Figures 24 - 27 are in a sense "mirror
images" of Figures 16 - 19, respectively, and
deserve only a few additional comments. It
should be kept in mind, however, that in analyz-
ing each sounding only the main inversion was
counted (see SECTION 2). This means that
secondary inversions, necessarily of the ele-
vated variety, may occur more often than indi-
cated, but only when a surface-based inversion
is present.
In Figures 24 - 27 in the vicinity of New
York City notice the anomalously high frequen-
cies of elevated inversions (at J. F. Kennedy
Airport). This feature lends further support to
the possibility mentioned earlier that it is
caused by an urban (megalopolitan) heat island.
For example, the input of anthropogenic heat
near the surface (and/or the retardation of
cooling) tends to raise the height of the base
of ground-based inversions. Consequently, there
are relatively fewer ground-based inversions and
more elevated inversions, as shown clearly by
the data in this report.
The relatively high frequencies of morning
elevated inversions that occur in central Texas
are not understood any better than the low
frequencies of ground-based inversions in the
same area. But there seems to be little likeli-
hood that they are caused by an urban heat island.
The frequencies of elevated inversions at
2315 GMT are shown in Figures 28-31. Unlike
the comparatively sparse occurrence of surface-
based inversions at 2315 GMT (Figures 20 - 23),
elevated inversions have frequencies of more
than 10 percent at all stations, except those in
the Rockies during summer. This indicates the
intense surface heating that occurs and that
typically extends through very deep layers
(i.e., at least 3 km). Notice that this surface
heating effect over the Rockies also shows up
clearly in the patterns for spring and autumn
(Figures 29 and 31), but is somewhat complicated
in winter (Figure 28). In all seasons the
frequencies of elevated inversions at 2315 GMT
are relatively high over the upper Midwest; they
are relatively low over the central Appalachians
and to some extent extending south and north
(i.e., in those areas with relatively high
frequencies of ground-based inversions at
2315 GMT (Figures 20 - 23). The most consist-
ently high values occur along the California
Coast, where they exr.eed 70-80 percent in all
seasons. The most complicated and seasonally-
variable patterns occur along and in the vicin-
ity of the Gulf and Atlantic Coasts. Appar-
ently, this is caused by various combinations of
seasonal variations in solar elevation at
2315 GMT, seasonal lag in ocean temperatures,
contrasts between coastal water and land tem-
peratures, and effects of local and regional
climate.
At 2315 GMT the frequencies of elevated
inversions (Figures 28 - 31) at San Juan
decline steadily from 59 percent in winter to
-------
24 percent in autumn. The reasons for this
variation are not known, but it agrees qualita-
tively with the complex variations along the
Gulf and south Atlantic Coasts. Both Hawaiian
stations have relatively high frequencies of
afternoon (in fact, near mid-day) elevated
inversions throughout the year with percentages
mostly in the 70s and upper 60s due to the trade
wind inversion. The three more southerly
Alaskan stations, Annette, Yakutat and Anchor-
age, have afternoon elevated inversion fre-
quencies ranging from 21 to 50 percent with no
clear consistent dependence on solar elevation
(as there is for surface-based inversions). The
remaining four more northerly Alaskan stations
have an interesting and readily explainable (for
the most part) seasonal variation of afternoon
elevated inversion percentages. Generally, the
frequencies increase from winter to spring,
decrease from spring to summer, remain about the
same from summer to autumn (except at Fair-
banks), and decrease from autumn to winter. The
main reason for this variation is the solar
elevation (see Figures 7 - 10). At these four
Alaskan stations in winter the sun is
always near the horizon at 2315 GMT and surface-
based inversions are relatively common, pre-
cluding the counting separately (by the criteria
i.sed in this study; see SECTION 2) of elevated
inversions. During spring the sun is for the
most part well above the horizon at 2315 GMT
(local times at the four stations are 1215 or
1315), nocturnal ground-based inversions have
not been completely eliminated, but surface
heating has eroded their bases so that they
appear as elevated inversions. Thus, the fre-
quencies increase from winter to spring. From
spring to summer the frequencies decrease
because summer solar heating is so effective
that some inversions have been eliminated, and
long-wave radiational cooling hasn't begun at
2315 GMT. From summer to autumn the frequencies
of elevated inversions near noon local time
increase sharply at Fairbanks, but remain about
the same at the other three stations, Nome,
Barrow, and Barter. This increase at Fairbanks
is attributed to the sun reaching a sufficiently
high elevation to convert nocturnal surface-
based inversions into elevated inversions and
being high enough at observation time to pro-
hibit the formation of surface-based inversions.
That this is more likely at the beginning of the
autumn season than at the end is indicated by
much higher frequencies of surface as well as
elevated inversions in autumn compared to summer
(see Figures 22, 23, and 30, 31). At Nome,
Barrow, and Barter, each on the coast, the
autumn frequencies are about the same as in
summer. This is thought to be caused by the
general seasonal lag in cooling of the oceans.
From autumn to winter elevated inversion fre-
quencies at 2315 GMT decrease markedly at all
four of the more northerly Alaskan stations.
The main cause of this variation is the sun
being very near the horizon at observation time,
resulting in an enhanced occurrence of ground-
based inversions. The entire seasonal variation
that has been described for the four more
northerly Alaskan stations is also true to some
degree for Anchorage, but is moderated by effects
of the ocean.
Heights of Tops of Surface-Based Inversions
Figures 32 - 35 show the seasonal frequen-
cies of all 1115 GMT soundings with a surface-
based inversion and with the top at least through
the indicated heights. It should be realized
that if the frequency of surface-based inversions
is small, the frequency of the heights of their
tops is necessarily small also. For reference,
the frequencies of surface-based inversions is
shown in the figures to the left of each sta-
tion. As a general rule, the data indicate that
practically all surface inversions are at least
100 m deep. In Figures 32 - 35, the isopleths
show the frequencies of surface-based inversions
with tops at least 250 m above the surface. In
the contiguous 48 states the greatest frequen-
cies occur in summer over the central inter-
mountain plateau with values barely exceeding
60 percent. Values exceeding 50 percent over
large regions occur in all seasons except
spring. The larger frequencies generally occur
over inland regions, except in summer large
values are also found over the northern Great
Lakes. This effect of the relatively cool water
surfaces is very probably much more prevalent
than indicated by the spacing of data points in
this report (e.g., see Lyons and Olsson, 1973),
and exemplifies the sort of attention to local
climatic features that should be made in inter-
polating/extrapolating from the data presented
here.
At San Juan and the two Hawaiian stations
surface-based inversions are rarely as deep as
-------
250 m; the more northerly Alaskan stations,
especially during winter, have frequencies of
that depth exceeding 50 percent. At Fairbanks
in central Alaska winter conditions are optimum
for development of deep radiation inversions;
the tops of such inversions exceed 250 m in
76 percent of all observations and they exceed
1500 m in 16 percent of all observations, more
than at any other station. Within the con-
tiguous 48 states surface-based inversions with
their tops above 1500 m occur in a few percent
of all 1115 GMT soundings at almost all stations
during winter; at International Falls and Caribou
the percentages are 12 and 10. Such deep inver-
sions are least common during the summer season
when they occur only at a few stations, notably
in Oregon.
At 2315 GMT ground-based inversions generally
are relatively weak, although they occur fairly
often in winter and autumn at the more easterly
and northerly stations; they are rather uncommon
in summer and spring when they are mainly con-
fined to the region from the Appalachians to the
East Coast (see Figures 20 - 23). Figure 36
shows the annual frequencies of ground-based
inversions at 2315 GMT and the frequencies of
the heights of such inversion tops. As depicted
by the isopleths, ground-based inversions with
tops at least 250 m above the surface occur in
more than 10 percent of all 2315 GMT soundings
only in the immediate vicinity of the Atlantic
Coast. As expected, deep surface-based inversions
at 2315 GMT are fairly common at the more
northerly Alaskan stations. Obviously, their
greatest occurrence is during the winter season.
Heights of Bases of Elevated Inversions
Figure 37 shows the annual frequencies of
all 1115 GMT soundings with elevated inversions
(seasonal frequencies were discussed in connec-
tion with Figures 24 - 27) and with inversion
base heights in the specified ranges above the
surface. Generally, these elevated inversion
base heights are spread over the entire range of
specified values. Exceptions occur at the
Hawaiian stations, especially Lihue, and at San
Juan where most of the elevated inversion base
heights are in the two highest intervals,
1001-2000 and 2001-3000 m above the surface. At
the two most northerly Alaskan stations, Barter
and Barrow, most elevated inversions are in the
two lowest intervals, 1-250 and 251-500 m, but
they also occur over the entire range of speci-
fied heights. Along the California Coast the
subsidence inversion base height of roughly
500 m readily shows up in the data. Throughout
many of the Plains states the most common ele-
vated inversion base height is in the range 251-
500 m with a frequency of around 10 percent.
The northeastern states have relatively frequent
occurrences of elevated inversions in the lower
height ranges and there is also a comparatively
large occurrence in the range of 1001-2000 m
for which the isopleths are shown. Notice the
10-percent isopleth along the Washington Coast,
and that it is consistent with the data for
nearby Annette.
Figures 38 - 41 show the seasonal frequencies
of all 2315 GMT soundings with elevated inversion
base heights in the indicated increments. Most
stations have some occurrences in all height
increments. Generally, the highest frequencies
occur in the range 1001-2000 m, but there are
many locations where other height ranges pre-
dominate. Isopleths are shown for inversion
base heights of 1001-2000 m in order to illus-
trate the continuity of the data, but this is
not meant to imply that the same patterns apply
for other inversion heights. For example, high
frequencies of elevated inversion bases rela-
tively close to the ground are confined to the
California Coast, especially during summer
(Figure 40). An excellent description of spatial
and temporal variations of this inversion base-
height over the Los Angeles Basin has been given
by Edinger (1959).
There is so much information in Figures 38 -
41 (and in other figures that follow) that it is
difficult to comment on all the potentially
significant features, and no attempt will be
made to do so.
Thicknesses of Elevated Inversions
Figures 42 - 45 show the seasonal fre-
quencies of all 1115 GMT soundings with an
elevated inversion and with the thicknesses of
such inversions (i.e., the height of the top
minus that of the bottom) exceeding the indi-
cated values. Isopleths illustrate the fre-
quencies of elevated inversion thicknesses that
exceed 500 m. Notice that the area with fre-
quencies exceeding 10 percent is most extensive
in winter (Figure 42) and smallest in summer
(Figure 44) but the highest frequencies by far
occur during summer along the California Coast.
-------
Figures 46 - 49 are the same as the previous
four, except these are for the 2315 GMT soundings.
Qualitatively, the seasonal variation of the
isopleth patterns is much like that for the
1115 GMT soundings (Figures 42 - 45).
Intensities of Surface-Based Inversions
In this report inversion intensities are
defined arbitrarily in terms of the average rate
of temperature increase through the inversion
layer. It is an average rate because it is
determined from temperatures only at the base
and top of each inversion, although there may be
sublayers with differing rates. Inversion
intensities were classified as follows:
Rate of
Temperature Increase
>6.00°C/100 m
2.83 to 6.00°C/100 m
1.15 to 2.82°C/100 m
0.48 to 1 .14°C/100 m
0.00 to 0.47°C/100 m
Inversion
Intensities
Very Strong
Strong
Moderate
Weak
Very Weak
Figures 50 - 53 show the seasonal frequencies
of all soundings at 1115 GMT with a surface-
based inversion and inversion intensities in the
specified classes for inversion thicknesses of
500 m or less and of more than 500 m. Notice
that in these figures the sum of all individual
frequencies for each station gives the frequency
of all ground-based inversions (except for
rounding to the nearest whole percent). The
data indicate that, generally, ground-based
inversion thicknesses of 500 m or less have
greater frequencies and intensities than deeper
ground-based inversions. The more northerly
Alaskan stations are exceptions in that during
winter they have considerably more deep than
shallow ground-based inversions, although the
more intense inversions are still the shallower
ones. Almost all stations have some relatively
shallow ground-based inversions with intensities
in all classes through very strong. On the
other hand, no station has any relatively deep
ground-based inversions that are classed as very
strong; many stations don't even experience any
strong intensities. Clearly, the overall
tendency for surface-based inversions at
1115 GMT is to have greater intensities asso-
ciated with shallower inversions.
In Figures 50 - 53 the isopleths are for
the percentages of ground-based inversions no
deeper than 500 m with a moderate inversion
intensity (middle value, left side of each
station). These conditions were selected for
isopleth analysis because of their relatively
high frequency of occurrence. Over the Rockies
and much of the Midwest these conditions are
most prevalent in summer and least prevalent in
winter. The strong isopleth gradient in the
vicinity of Louisiana during summer (Figure 52)
is a reflection of a relatively high frequency
of ground-based inversions at Lake Charles, as
discussed in connection with Figure 18.
Figure 54 shows values of the same vari-
ables as the previous four figures, except these
are on an annual basis and for soundings at
2315 GMT. Since ground-based inversions are
uncommon at this observation time, except at
some Alaskan stations in the colder months, the
frequencies are for the most part very low. As
shown by the isopleths, there are only a few
stations with barely a 10-percent frequency of
afternoon/evening ground-based inversions that
extend through no more than 500 m and that have
an intensity of moderate.
Intensities of Elevated Inversions
Figures 55 - 59 are similar to the previous
series, except these are for the intensities of
elevated inversions. Isopleths are for inver-
sions with an intensity of weak and with thick-
nesses of 500 m or less. Figure 55 shows the
isopleths and annual data for 1115 GMT soundings.
Notice that there are relatively few elevated
inversions at this time in the general vicinity
of the Rocky Mountains and relatively more along
the Atlantic Coast. Of those inversions that do
occur at 1115 GMT, most have a thickness of 500 m
or less with intensities of very weak and weak
but almost all stations experience some very
strong intensities. On the other hand, for
inversion thicknesses greater than 500 m no
station experiences any intensities of very
strong and few report any that are classed as
strong. The two more northerly Alaskan stations,
Barter and Barrow, are exceptions in that they
have more deep than shallow thicknesses of
elevated inversions. For the same reason Santa
Monica and San Diego, California are almost
exceptions due to the relatively deep and intense
subsidence inversion that predominates along the
California Coast during summer. It is also
interesting to note the disparity between the
data for Lihue and Hilo, Hawaii, due essentially
-------
to the predominance of surface-based inversions
at Hilo. In general, the thickness and inten-
sity characteristics of elevated inversions at
1115 GMT are much like those of ground-based
inversions.
At 2315 GMT (Figures 56 - 59) there are
generally considerably more elevated inversions
than at 1115 GMT, but otherwise the thickness
and intensity characteristics are rather simi-
lar. For example, at most stations there are
more thin (<500 m) than thick (<500 m) elevated
inversions and the thinner ones tend to be more
intense, although relatively few occur with an
intensity of very strong. At most stations the
most common intensity of elevated inversions is
very weak.
Figures 56 - 59 include the seasonal iso-
pleths of the frequency of weak intensity inver-
sions with thicknesses of 500 m or less at
2315 GMT. In winter (Figure 56) most frequencies
are around 10 - 20 percent; they are lower along
the coastlines, except along the California
Coast. Notice that values for the Hawaiian
stations are quite similar to those for stations
along the California Coast. Similarly, there is
good agreement between San Juan and Miami.
Spring (Figure 57) is much like winter although
the area with frequencies less than 10 percent
has grown larger. This trend continues into
summer (Figure 58) at which time there are few
stations with thin elevated inversions of weak
intensity. However, along the California Coast
in summer the most frequent inversion intensity
is moderate for both thick and thin inversion
layers. The autumn isopleth pattern (Figure 59)
is much like that of summer.
Superadiabatic Temperature Differences in No-
Inversion Soundings
Thus far the discussions have been con-
cerned with the characteristics of temperature
inversions. In this subsection and in the one
that follows the emphasis is on superadiabatic
temperature differences as they occur in sound-
ings with no inversion and in soundings with
elevated inversions. Superadiabatic is defined
here as a temperature decrease with height
exceeding 1.20°C/100 m. Isopleths have been
omitted from this series of maps because no one
set of data stands out as occurring more fre-
quently than another. Figures 60 - 63 show the
seasonal percentages of 2315 GMT soundings with
no inversion below 30QO m and with superadiabatic
temperature differences in the specified layers.
Notice that these temperature differences are
determined from the temperatures at the tops and
bottoms of the layers; therefore, they are
averages. It should be emphasized that because
of the lag in rawinsonde temperature sensors,
superadiabatic conditions tend to be underesti-
mated (i.e., the soundings are often more unstable
than indicated)!
Figure 50 shows that during winter, 2315 GMT
soundings with no inversion are unusual—and
superadiabatic conditions are even more unusual —
except in the West. But even there, such
unstable conditions are confined mainly to the
lowest layer, 1-100 m; they occasionally extend
through the layer 101-250 m but rarely higher.
Following the solar cycle the frequencies
increase during spring (Figure 61) and reach a
maximum in summer (Figure 62) when there are
five stations in the Rockies (Glasgow, Winnemucca,
Grand Junction, winslow, and Albuquerque) with
superadiabatic frequencies of 10 percent or more
(with respect to all soundings) in the layer
251-500 m. In this same region there are a few
stations that have superadiabatic frequencies of
a few percent in the layer 501-750 m and a very
few with one-percent frequencies in the 751-
1000-m layer. Notice in Figure 62 that along
the California Coast there are very few sound-
ings with no inversions and therefore the
occurrence of associated superadiabatic condi-
tions is nil. The Hawaiian stations and the
more southerly Alaskan stations all have signi-
ficant frequencies of superadiabatic temperature
differences, at least in the 1-100-m layer,
unlike the relatively very low frequency at San
Juan which resembles the values along the south
Atlantic seaboard.
During autumn (Figure 63) the data are much
like those for summer although the frequencies
tend to be somewhat less, due essentially to the
lower solar elevations at observation time. The
effect in the eastern states of lower solar
elevations contributing to less instability than
would have occurred with higher sun (i.e.,
comparable to those at 2315 GMT in the West) is
indicated in Figure 64. The data in this figure
are the same as in Figure 62 (summer, 2315 GMT),
except these are for a temperature decrease with
height of more than 0.80°C/100 m (in Appendix A
neutral conditions are defined as temperature
decreasing with height in the range 0.81-
1.20°C/100 m). Figure 64 shows that at most
10
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western stations, especially in the Rockies, the
stabilities of practically all lower layers of
no-inversion soundings are near neutral or less
stable. But proceeding eastward the frequencies
drop off progressively, indicating the effects
of surface cooling by observation time. It is
speculated that if soundings in the eastern
United States were taken at comparable solar
times to those in the western mountains, the
frequencies of superadiabatic conditions in the
East would be greater than indicated, but would
not exceed values over the mountains. This is
because the transmission of solar radiation to
the mountains and its absorption there is
enhanced by the elevation, aridity, and nature
of the surface.
Since at 1115 GMT there are few stations
with more than a very few percent of no-inver-
sion soundings (see Figure 11), there are even
fewer occurrences of associated superadiabatic
conditions. At 1115 GMT no-inversion soundings
are more common along the Oregon-Washington-
southern Alaska Coasts where seasonal frequen-
cies reach 20-40 percent. Even so, supera-
diabatic conditions in such soundings are rare
and are confined essentially to the layer
1-100 m.
Superadiabatic Temperature Differences Below
Elevated Inversions
The data in this subsection are similar to
those in Figures 60 - 63, except these are for
superadiabatic conditions in the entire layer
beneath elevated inversion bases and they are
broken down by inversion base heights. Thus,
except for the lowest layer (1-100 m), where
inversion bases seldom occur, the temperature
differences in this subsection are necessarily
averaged over deeper layers than in the previous
subsection. Figures 65 - 68 show the seasonal
frequencies of a temperature decrease with
height exceeding 1.20°C/100 m in the layer
beneath elevated inversions, by inversion base
height, for 2315 GMT soundings. Notice that for
each station, within rounding errors, the sum of
figures on the left gives the total percentage
of all soundings with an elevated (above surface)
inversion base within 3000 m of the surface.
The corresponding figures on the right of each
station give the percentages of all soundings
with an elevated inversion base in the indi-
cated height range and with a superadiabatic
temperature difference in the layer below the
inversion. Thus, the proportion of those
inversion base heights that subtend a super-
adiabatic layer may be readily determined.
Figure 65 shows the data for winter soundings
at 2315 GMT. In general, although elevated
inversions are fairly frequent at most stations,
superadiabatic conditions in the layers below
them hardly occur at all in the East and occur
occasionally in the West. The effects of
differing solar elevations show up again and in
addition there is the effect of superadiabatic
conditions being more likely in layers closer
to the surface (i.e., in the layer beneath
lower inversion base heights. For example, in
Figure 65 at stations in the West, the highest
proportions of inversions that are underlain by
superadiabatic layers are for the lower inversions.
The average temperature change below higher
level inversions is seldom superadiabatic.
Notice that this effect is especially pronounced
at Santa Monica and San Diego where the 2315 GMT
soundings practically always have an elevated
inversion, a comparatively high proportion of
which have bases at low levels. On the other
hand, the Hawaiian stations and San Juan have
mostly high level inversions, rarely with
superadiabatic layers (as defined here) below.
It is interesting that all of the Alaskan
stations have some occurrences of superdiabatic
conditions below inversions—even in winter.
Proceeding to spring (Figure 66) there is a
general tendency for inversion bases to occur
at higher levels and for a high proportion of
superadiabatic conditions in the layers below,
especially below low-level inversions. This is
particularly evident at the northern Alaskan
stations . Over the Rockies the effects of
increasing solar radiation lead to a marked
decrease in frequency of inversions below 3000 m.
By summer (Figure 67) there are very few inver-
sions within 3000 m of the surface at 2315 GMT
over the Rockies, in accord with the afternoon
mixing height calculations of Holzworth (1972).
In the East, especially along the middle and
northern Atlantic Coasts, there are some occur-
rences at 2315 GMT during summer of superadia-
batic conditions below the lower elevated
inversions. This effect is very pronounced
along tho Pacific Coast, particularly of
California, where there is a high frequency of
inversion bases within 500 m of the surface, of
-------
which an exceptionally high percentage are
underlain by superadiabatic conditions. To a
significant, but lesser degree, this is also
true at the two most northerly Alaskan sta-
tions. The data for autumn (Figure 68) are
generally intermediate between summer and
winter.
Although elevated inversions at 1115 GMT
do occur frequently at some some stations in
some seasons (see Figures 24 - 27) only very
rarely are they associated with superadiabatic
temperature differences in the underlying
layer. For example, at Oakland, elevated
inversions with bases below 500 m occur in
45 percent of all 1115 GMT summer soundings,
but the underlying layer is superadiabatic in
only slightly more than one percent of all
soundings. Curiously, the two more northerly
Alaskan stations, Barter and Barrow, have by
far the highest seasonal frequencies of ele-
vated inversions at 1115 GMT with superadia-
batic conditions below, about 7 percent at both
during summer.
RELATIVE HUMIDITY VS VERTICAL TEMPERATURE
STRUCTURE
Two principal processes for which relative
humidity is an important factor are atmospheric
chemical transformations (e.g., sulfur dioxide
to sulfate aerosol) and enhanced fog and cloud
formation as a result of cooling tower emis-
sions. Although the figures include frequencies
of relative humidities exceeding 69 and 89 per-
cent for ground-based as well as layers aloft,
the isopleth analyses focus on humidities
exceeding 69 percent in the ground-based layer.
It should be emphasized that the relative
humidities are averages for the layers being
considered (see SECTION 2) and such layers may
display considerable internal variation. This
is particularly true of ground-based radiation
type inversions in which the relative humidity
(and often the absolute humidity) profiles are
typically mirror images of the temperature
profiles. Largely, because of this phenomenon
the average relative humidity of the layers
considered here seldom exceeds 89 percent.
Within Surface-Based Inversions
Figures 69 - 72 show the isopleths of
seasonal percentages of all 1115 GMT soundings
with a surface-based temperature inversion in
which the relative humidity exceeds 69 percent.
Obviously, the frequency of such conditions is
limited by the frequency of surface-based
inversions (Figures 16 - 19). Generally, at
1115 GMT in all seasons (Figures 69 - 72) the
occurrence of surface-based inversions with an
average relative humidity greater than 69 per-
cent is comparatively high in the vicinity
of the south Atlantic and Gulf Coasts, and
extending inland over Oregon and Washington.
In addition, during summer (Figure 71) there is
a distinct high-frequency area extending north-
eastward from Lake Charles, whose value of
92 percent is the highest for any station. The
second highest summer value, 82 percent,
occurs at Hilo. In fact, all seasonal values
at Hilo range from 77 to 88 percent. The
disparity between the data for Hilo and nearby
Lihue has already been discussed in terms of
surface-based inversion frequencies. Neverthe-
less, the occurrence at Hilo and Lake Charles
of high percentages of surface-based inversions
with very high proportions of relative humidity
exceeding 69 percent is difficult to explain.
The intense isopleth gradients along the Texas-
Louisiana Coast during summer are apparently
related to the distribution of surface-based
inversions as discussed in connection with
Figure 18. Those regions generally associated
with comparatively low frequencies of ground-
based inversions that have average relative
humidities exceeding 69 percent are over the
Rockies, especially in the south and along
their eastern slopes into the Plains, along the
Washington Coast, and in the vicinity of New
York City. The latter small area is due to the
anomalously low frequencies of surface-based
inversions that occur there.
The distribution of 2315 GMT soundings
with a surface-based inversion and an average
relative humidity exceeding 69 percent is shown
in Figure 73 on an annual basis since such
conditions are so unusual. The only places
where the values exceed 10 percent are along
the Atlantic Coast, along the central Gulf
Coast, and at the two more northerly Alaskan
stations, Barter and Barrow. An obvious main
reason for the low values is the local times,
late afternoon/evening, when the soundings are
made. At these times the surface temperatures
would still be somewhat high and the relative
humidities would necessarily be low.
12
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Below Elevated Inversions
Figures 74 - 77 show the seasonal per-
centages of all 1115 GMT soundings with an
elevated inversion (i.e., with a base between
1 and 3000 m) for which the average relative
humidity in the subinversion layer and within
the inversion layer exceed 69 and 89 percent.
Isopleths are shown for average relative
humidities exceeding 69 percent in the subin-
version layer. Most of these isopleth pat-
terns, except perhaps for the East Coast, are
very similar to the corresponding seasonal ones
for the frequencies of all elevated inversions
(Figures 24 - 27). Notice the intense gradient
in summer (Figure 76} along the California
Coast in the transition zone between moist
marine air and arid continental air. Actually,
this gradient may in fact be more intense than
indicated in the figure (as well as in the same
area of other figures). In general, a high
proportion of morning elevated inversions has
average relative humidities in the underlying
layer that exceed 69 percent. This is also
true to a considerable extent for those stations
plotted around the periphery of the figures.
Figures 78 - 81 are the same as the previous
series, except these are for soundings at
2315 GMT. For the most part the data and
analyses for 2315 GMT are quite similar to
those for 1115 GMT. The most prominent excep-
tion occurs during the summer (Figure 80) over
Texas where a relatively high frequency in the
morning (1115 GMT) is completely absent in the
evening (2315 GMT). Also in summer the intense
gradient along much of the California Coast in
the morning is limited more to the south in the
evening. In general, similarities between the
isopleth patterns of elevated inversion fre-
quencies and of elevated inversions with average
relative humidity in the layer below exceeding
69 percent are not as great at 2315 GMT as at
1115 GMT, especially for the eastern United
States (e.g., see Figures 78 - 81 and 28 - 31;
74 - 77 and 24 - 27).
For No Inversion
Figures 82 - 85 show the seasonal fre-
quencies of all 1115 GMT soundings with no
inversion below 3000 m and with average rela-
tive humidities in specified layers exceeding
69 and 89 percent. An interesting feature of
these charts for both observation times and for
both humidity classes is the general uniformity
of the frequencies throughout the lower 1500 m
of the soundings. This is not surprising since
for no-inversion soundings, a rather uniform
vertical distribution of moisture is generally
expected. Isopleths are shown for percentages
of relative humidity exceeding 69 percent in
the 251-500-m layer, but clearly the isopleths
are typical of most layers that were considered.
In viewing this series of charts it should be
kept in mind that the upper limiting value for
any entry is the percentage of no-inversion
observations. Thus, at 1115 GMT only a few
locations have no-inversion percentages greater
than 30 on an annual basis (see Figure 11).
Accordingly, there are only a few stations in
California, Oregon, Washington, Alaska, and
Hawaii where more than 10 percent of all 1115
1115 GMT winter soundings have no inversion and
an average relative humidity greater than
69 percent in the 251-500-m layer (as well as
for most layers considered; see Figure 82).
At the stations along the Pacific Coast these
relatively moist conditions are associated with
synoptic-scale storms that frequent the region.
The spring chart (Figure 83) is very similar to
that for winter, except the moisture is greater
in the tropics and in the region south of the
eastern Great Lakes. The occurrence of no-
inversion soundings at 1115 GMT with compara-
tively high relative humidities reaches a
maximum in summer (Figure 84) along the Gulf
and Atlantic Coasts. Notice on this chart that
during the summer there is less uniformity in
the frequencies among the layers for each
humidity class than during any other season.
There are more occurrences of relatively high
moisture at low levels than at high levels; for
example, at Burwood for humidities exceeding
69 percent and at Jacksonville for humidities
exceeding 89 percent. Also, notice that during
summer all but the two most northerly Alaskan
stations have at least 10 percent of all
1115 GMT soundings with no inversion and relative
humidities greater than 69 percent for layers
below 1500 m. The data for autumn (Figure 85)
are much like those for winter (Figure 82) with
few locations having more than 10 percent of
all 1115 GMT soundings with no inversion and
with relative humidities greater than 69 percent.
But notice that the frequencies remain compara-
tively high at most Alaskan stations.
13
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Figures 86 - 89 are for the same criteria
as the previous four, except these are for
2315 GMT soundings. The corresponding seasonal
data and isopleth patterns are remarkably
similar for the two observation times. This
happens over the 48 contiguous states in spite
of the fact that there are generally consider-
ably more no-inversion cases at 2315 GMT (see
Figures 12 -15) than 1115 GMT (see Figure 11).
It occurs in general because a large proportion
of no-inversion soundings at 2315 GMT are
comparatively dry (e.g., over the Rockies
especially during summer; see Figures 14 and
88). On the other hand, for the Alaskan,
Hawaiian, and San Juan stations the frequen-
cies of soundings with no inversion and
comparatively high humidities are markedly
greater at 2315 GMT than at 1115 GMT. Fur-
thermore, at these stations there is a tend-
ency for more high humidities at higher
levels in the 2315 GMT soundings.
WIND SPEED VS VERTICAL TEMPERATURE STRUCTURE
In general considerations of transport
and diffusion the vertical structure of the
wind is at least as important as the tem-
perature structure. As described in
Appendix A, considerable details are given in
the original summaries on wind structure
through 1200 ro (above the surface) as a
function of temperature structure. But because
there are so many variables and because the
winds, especially directions at low levels,
are highly dependent upon local features, data
are presented only on wind speeds at the
surface and at 300 ra above the surface. These
data are subdivided according to soundings
with a surface-based inversion, an elevated
inversion, or no inversion. "Surface" winds
refer to fixed sensors mostly at 6-8 m above
ground although some may have been higher. No
isopleth analyses are presented because generally
at each station significant values occur for
several of the speed classes.
For Surface-Based Inversions
Figures 90 - 93 show the seasonal frequencies
of all 1115 GMT soundings with an inversion
base at the surface and with surface and 300-m
winds in the indicated speed classes. Notice
that on these charts the sum of all surface
wind speed frequencies and of all 300-m wind
speed frequencies each are equal to the frequen-
cies of all ground-based inversions.
Figure 90 indicates that at 1115 GMT
during the winter, surface-based inversions
are generally associated with considerably
faster winds at 300 m than at the surface.
For example, at Nashville, Tennessee, the
frequency of speeds in the classes, calm,
0.1-2.5, and 2.6-5.0 m/sec are each greater at
the surface than at 300 m and the frequency of
speeds in the classes 5.0-10.0 and >10 m/sec
are each greater at 300 m than at the surface.
For most stations the most common speed class
of surface winds with surface inversions is
2.6-5.0 m/sec. Amarillo, Dodge City, Ely,
fireat Falls, and Nome are exceptional for
their relatively high frequencies of surface
speeds exceeding 5.0 m/sec. On the other
hand, Medford and Lander (both located within
bowl-shaped terrain) are exceptional for their
high frequencies of surface and 300-m speeds
less than 2.6 m/sec—optimum conditions for
atmospheric stagnation. Medford and Lander
also have by far the highest frequencies of
winter soundings with surface inversions and
calm surface speeds; other stations with
relatively high frequencies are Salem, Winne-
mucca, Oakland, Albany, Yakutat, Fairbanks,
and San Juan.
While there are some variations, the
general features of wind speed characteristics
with inversions based at the surface at
1115 GMT in winter are similar to those in the
other seasons. Notice that during summer
mornings (Figure 92) Medford experiences
surface inversions with surface wind speeds
less than 2.6 m/sec in 62 percent of the
observations! In general, there tend to be
more slow surface speeds with surface inver-
sions during summer than winter, especially in
the eastern United States.
Figures 94 - 97 are the same as the
previous four except these are for 2315 GMT,
afternoon/evening, soundings. As mentioned in
discussions of the data presented earlier, the'
values on these charts are highly dependent on
seasonal changes in solar elevation at the
sounding time. Accordingly, the highest
frequencies of surface inversions at 2315 GMT
occur during winter in the more eastern and
northern stations, and the lowest frequencies
occur during summer with hardly any. Where
-------
and when surface inversions do occur at
2315 GMT, e.g., mainly during winter and
autumn (Figures 94 and 97), the frequencies of
speeds in the classes calm, 0.1-2.5, and
2.6-5.0 m/sec almost invariably are greater
for surface than for 300-m winds, and in the
classes 5.1-10.0 and >10.0 m/sec the frequen-
cies are usually greater for 300-m winds than
for surface winds. Also notice on these
figures that during winter and autumn most
stations experience relatively few calm
surface winds; surface speeds are most com-
monly in the speed range 2.6-5.0 m/sec. Thus,
either the formation of radiation inversions
beginning around sunset does not require
exceptionally slow surface winds or the
drainage winds that are often associated with
radiation inversions develop rather quickly.
It is worth noting that the high frequencies
of extreme stagnation conditions (a low-level
inversion with surface and 300-m winds
<2.6 m/sec) mentioned earlier for Medford and
Lander in connection with the 1115 GMT sound-
ings occur in only around 1 percent of the
2315 GMT soundings at Lander and not at all at
Medford during spring and summer. At these
stations the greatest frequencies of extreme
stagnation at 2315 GMT occur in winter with
19 percent at Lander and 7 percent at Medford.
These are probably the limiting percentages
that extreme stagnation (as defined here) may
be expected to persist through at least one
complete diurnal cycle at these stations. As
expected, the indicated stagnation conditions
are not at all so unusual at some Alaskan
stations, especially during winter when they
may persist for days.
For Elevated Inversions
The next series of charts is similar to
the last series, except this one is for
elevated inversions; the charts show percent-
ages of all soundings with an elevated inver-
sion base 1-3000 m AGL with surface and 300-m
wind speeds in specified classes. Since most
stations have comparatively few elevated
inversions with base heights 300 m or less,
the wind data for the surface and the 300-m
levels both generally may be considered as
being below the inversion base. There are
some exceptions, however; notably for 1115 GMT
soundings on an annual basis (see Figure 37)
at Barter and Barrow where elevated inversions
occur in about 50 percent of the soundings and
of those elevated inversions about 30 percent
have bases in the range 1-250 m. Somewhat
similar exceptions also occur in the 2315 GMT
soundings, mainly at the California stations
and at some Alaskan stations in certain sea-
sons (see Figures 38 - 41).
As a general rule for 1115 GMT soundings,
the main difference in both surface and 300-m
wind speeds between inversions based at the
surface (Figures 90 - 93) and aloft (i.e.,
1-3000 m; Figures 98 101) is that the winds
with elevated inversions have higher frequen-
cies of faster winds. The differences are
typically greater for the surface wind than
for the 300-m wind. For example, at 1115 GMT
during winter (Figure 90) Columbia, Missouri
has inversions based at the surface in almost
50 percent of the observations. With respect
to these same low-level inversions the speeds
exceed 5.0 m/sec in 3 oercent of the surface
wind observations and in 74 percent of the
300-m wind observations. But of those sound-
ings with elevated inversions (Figure 98),
5.0 m/sec is exceeded in 46 percent of the
surface wind observations and in 84 percent of
the 300-m wind observations. As a consequence
of the comparatively fast wind speeds asso-
ciated with 1115 GMT elevated inversions,
speeds less than 2.6 m/sec generally occur
relatively seldom with these elevated inver-
sions. At many locations the frequencies
don't exceed a few percent, even at stations
where elevated inversions are rather common.
But as usual there are exceptions, notably at
Medford during winter (Figure 98), at the
California coastal stations throughout much of
the year (Figures 98 - 101), and to some
extent at a few raid-continental and Alaskan
stations in certain seasons.
The seasonal distribution of surface and
300-m wind speeds with elevated inversions at
2315 GMT are shown in Figures 102 - 105. At
this observation time elevated inversions are
generally much more common than at 1115 GMT,
except over the Rockies during summer. As
usual, the 300-m speeds are typically faster
than the surface speeds. At both elevations
speeds less than 2.6 m/sec occur with sur-
prisingly high frequencies during winter
(Figure 102) over much of the Rockies, to some
15
-------
extent along the Pacific Coast, and at Anchor-
age and Fairbanks. The frequencies of slow
wind speeds with elevated inversions at
2315 GMT are comparatively low during spring
and summer (Figures 103 and 104), except at
some Alaskan stations. During autumn
(Figure 105) the frequencies of elevated
inversions with wind speeds less than
2.6 ra/sec are comparatively high at several
stations scattered throughout the continental
states; the highest frequencies occur at
Medford, 37 percent for surface winds and
33 percent for 300-m winds.
For No Inversions
The distributions of surface and 300-m
wind speeds for 1115 GMT soundings with no
inversion below 3000 m are shown annually
(Figure 106) since no-inversion soundings
generally occur infrequently at this obser-
vation time (e.g., see Figure 11). The most
notable exceptions are at Anchorage, Yakutat,
Annette, Tatoosh, El Paso, Burwood, Tampa,
Miami, Hatteras, New York City, Buffalo, and
San Juan. At most of these places the most
frequent surface speed is 2.6-5.0 m/sec and
the most frequent 300-m speed is somewhat
faster.
The distributions of surface and 300-m
wind speeds for 2315 GMT soundings with no
inversion are shown seasonally in Figures 107 -
110. As may be deduced from Figures 12 - 15,
at 2315 GMT soundings without inversions are
most common in all seasons over the Rockies
where the frequencies generally exceed
9D percent during winter. No-inversion
soundings at 2315 GMT barely occur along the
California Coast during summer and at the more
northerly Alaskan stations, especially during
winter. As with the other wind charts already
discussed, no isopleths are shown for the no-
inversion cases since the speeds typically
occur over broad ranges. As was generally
found with inversions, the 300-m speeds are
usually faster than the surface speeds when
inversions are absent. At most stations the
most frequent surface speeds are in the range
2.6-5.0 m/sec while the 300-m wind speeds most
frequently are in the range 5.1-10.0 m/sec.
At many stations during winter the surface and
30Q-m wind speeds with no-inversion soundings
(Figure 107), tend to be somewhat faster than
with elevated inversions (Figure 102) but
during summer (see Figures 109 and 104) the
differences are small.
SECTION 4
SUMMARY AND CONCLUSIONS
Most studies of the transport and diffu-
sion of man-made air pollution are concerned
with the properties of the lowest few kilo-
meters or so of the atmosphere. In general,
direct measurements of atmospheric structure
are restricted to a few tens of meters, or at
most a few hundred meters above the surface—
except for the routine balloon-borne rawin-
sonde measurements of the National Weather
Service. Over the years a format/method
(described in the Appendix) was developed for
summarizing these sounding data from individual
stations for use in air pollution studies.
The purpose of this report is to present some
main features of those summaries on maps of
the United States. Together, these maps
represent a climatological atlas of atmos-
pheric features that are important in pollu-
tion dispersion within the lower few kilo-
meters of the atmosphere.
Detailed data are presented in this
report on three important parameters, tem-
perature structure or stability, wind speed,
and relative humidity. The latter is impor-
tant in pollutant transformations as well as
fog and cloud formation. With few exceptions
the summarized data are based on soundings
taken twice daily over at least 5 years at
76 locations. The balloon-borne sensors were
released near 2315 and 1115 GMT, which gener-
ally conform to local times of instability and
stability, respectively. In order to view the
sounding data in regard to potential effects
of solar heating and long-wave radiational
cooling, solar elevation angles are presented
for both balloon release times on the middle
day of each season.
Although this report includes 100 maps of
rawinsonde-derived data, they represent only a
portion of the potentially useful information
in the original data tabulations. Some of the
maps are isoplethed to illustrate spatial
continuity and variations, but no attempt was
made to isopleth all of the parameters that
are presented.
16
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All of the rawinsonde data are presented
in percentages with respect to the total number
of soundings at each observation time, season-
ally or annually.
Most of this report is devoted to descrip-
tions of the vertical temperature structure of
the near-surface atmosphere. Generally, it is
found that inversions in this layer are the
rule at 1115 GMT in all seasons. This is also
generally true for soundings at 2315 GMT,
except during summer, when only northern
Alaska, the immediate Pacific Coast, the upper
Atlantic Coast, and the upper Midwest have
inversions in more than half the observations.
The Rocky Mountain region has by far the lowest
frequency of inversions at 2315 GMT in all
seasons; they occur in less than half the
soundings in all seasons except winter.
Surface-based inversions predominate at 1115 GMT
(morning), except in the extreme Northwest and
around New York City where elevated inversions
are more common. At 2315 GMT (afternoon)
surface-based inversions are most frequent in
the East, especially during winter and autumn,
largely as a consequence of low solar elevations
at observation time. Conversely, elevated
inversions are generally most prevalent during
the afternoon and particularly along the Cali-
fornia Coast where the frequencies exceed
SO percent during summer.* Most of the data in
*It should be noted that in this report no more than
one inversion is tabulated per sounding. The base of
that inversion is defined as the base of the lowest
inversion within 3000 m of the surface and the top as
that of the inversion with the highest actual tempera-
ture within 4500 m of the surface. Thus, some elevated
inversions could be neglected.
this report show reasonable spatial and temporal
continuity in regard to well-known climatic
features. However, there are some unexplain-
ably (to us) large differences in percentages
of of surface and elevated inversions across
the Louisiana and Texas Gulf Coast area, pri-
marily during summer mornings, that serve to
point out'that the data are most representative
of those locations where the observations were
taken.
The tops of surface-based inversions are
most always greater than 100 m and sometimes
range to at least 1500 m AGL. Such deep
inversions usually occur during winter mornings
and are most prevalent at International Falls,
Caribou, and the more northerly Alaskan stations.
The bases of elevated inversions generally
have some occurrences at all levels to 3000 m
at both observation times, but there are
distinct regional and seasonal variations in
their vertical distribution. Overall, elevated
inversions are more frequent at 2315 GMT; they
are virtually always thicker than TOO m and
have a tendency toward greater thicknesses in
the colder the colder seasons during both
mornings and afternoons. However, even in
winter at most locations fewer than half of the
soundings have elevated inversions that are
thicker than 500 m. Although the spatial
extent of such inversions is least during
summer, the highest frequencies at individual
locations occur then, exceeding 50 percent at
Santa Monica and San Diego at both observation
times.
17
Five classes of inversion intensity
(i.e., AT/AZ) are specified with an overall range
from 0.00 to >6.00 °C/100 m. For surface-based
inversions the intensities are typically
greater for thicknesses less than 500 m than
for thicknesses more than 500 m. No station
has any surface-based inversion intensities in
the most extreme class for thicknesses exceed-
ing 500 m. For elevated inversions the intensi-
ties vary with thickness in the same manner as
for surface-based inversions, but the intensities
are characteristically less for elevated inver-
sions.
Soundings with no inversion, which are
most common during summer afternoons, have
relatively frequent occurrences of superadia-
batic conditions (-AT/AZ > 1.2 °C/100) in the
layer 1-250 m AGL; such instability infre-
quently reaches heights greater than 1000 m
AGL, mostly over the Rocky Mountains. Super-
diabatic conditions also occur beneath elevated
inversions with relatively higher frequencies
in the shallower subinversion layers.
Average relative humidities in inversions
and in adjacent layers have some interesting
distributions. As might be expected, surface-
based inversions with higher relative humidi-
ties are most frequent in coastal areas through-
out the year, but also in the Midwest and East
during summer and autumn. Surface-based inver-
sions are almost invariably more humid than
are the 300-m layers immediately above them.
For elevated inversions the subinversion layer
is typically more humid than the inversion
layer, but the differences are less nronounced
-------
than for surface inversions and the layer
immediately above. For no-inversion soundings
high relative humidities occur with rather
equal frequencies in sublayers through 1500 m
AGL. This uniformity is somewhat more consist-
ent for afternoon than for morning soundings.
Wind speeds at 300 m AGL are generally
faster than surface speeds although this is
more apparent in the presence of an inversion.
Calms at 300 m at any time are rare except at a
few stations. The most frequent wind speed
range is 2.6-5.0 m/s at the surface but is
quite variable at 300 m. Faster wind speeds at
the surface generally occur more frequently in
the Plains and the Pacific Northwest, espe-
cially when there is no inversion.
Many of the descriptions and most of the
conclusions in this report are highly general-
ized. As such they should be considered as
guidance. In particular, those data for
individual stations are most representative of
those locations and interpolation/extrapolation
to other places should be done with utmost care.
REFERENCES
Badgley, F. I., 1957. Response of radiosonde
thermistors. Bull. Amer. Meteor. Soc 28
1079-1084. ~ ~~~—
Bilello, M. A., 1966. Survey of arctic and sub-
artic temperature inversions. Tech. Rpt. 161,
U.S. Army Material Command, Cold Regions
Research and Engineering Laboratory, Hanover,
New Hampshire, 35 pp.
Edinger, J. G., 1959. Changes in the depth of
the marine layer over the Los Angeles Basin.
J. Meteor., U, 219-226.
Ference, M., Jr., 1951. Instruments and techniques
for meteorological measurements. Compendium
of Meteorology, 1207-1222. American Meteo-
rological Society, Boston, Massachusetts,
1334 pp.
Holzworth, G. C., 1972. Mixing heights, wind
speeds, and potential for urban air pol-
lution throughout the contiguous United
States. Environmental Protection Agency,
Office of Air Programs, Publication
AP-101, Research Triangle Park, North
Carolina, 118 pp.
Hosier, C. R., 1961. Low-level inversion fre-
quency ii the contiguous United States.
Mon. wea. Rev.. 89, 319-339.
Lyons, W. A., and L. E. Olsson, 1973. Detailed
mesometeorological studies of air pollution
dispersion in the Chicago lake breeze.
Hon. Hea. Rev., 101, 387-404.
Munn, R. E., J. Tomlain, and R. L. Titus, 1970.
A preliminary climatology of ground-based
inversions in Canada. Atmosphere, 8, 52-68.
Nieburger, M. , D. S. Johnson, and C. W. Chien,
1961. Studies of the structure of the
atmosphere over the eastern Pacific Ocean
during summer. University of California
Press, Los Angeles, 94 pp.
Roberts, J. J., 1977. Report to U.S. EPA of
the specialists conference on the EPA
modeling guideline. Prepared by Argonne
National Laboratory, Energy and Environ-
mental Systems Division, Chicago, Illinois,
322 pp. See especially pp. 29-31,44, 56,
and 245.
18
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APPENDIX A
DATA FORMATS AND AVAILABILITY
This appendix provides detailed descrip-
tions of the processed sounding data that are
stored on magnetic tape, of the climatologi-
cally summarized data stored as hard copy, the
stations and periods of record that have been
summarized, and the availability of the data.
FORMATS OF INDIVIDUALLY PROCESSED SOUNDINGS
Table A-l shows an example of a page of
computer printout of processed sounding data
stored on magnetic tape. One line is used for
each sounding. Missing data are indicated by
9s. The stored data for each sounding are each
in one of three possible formats, depending on
whether the sounding showed (1) a surface-based
inversion, (2) an inversion base aloft within
3 km of the surface, or (3) no inversion within
3 km. Table A-2 shows details of the three
possible formats.
Surface-Based Inversions
In Table A-2 in the format example for
surface-based inversions, 23066 (STA) is the
WBAN station number, Grand Junction, Colorado;
60 (YR) is the year, 1960; 02 (MO) is the
month, February; 18 (DA) is the day of month;
and 12 (HR) is the scheduled rawinsonde obser-
vation time, 1200 GMT. In the United States it
has been common practice to release the rawin-
sonde balloons about 45 minutes before the
scheduled times. Continuing with the first
example, 120 (SFC) is the surface wind direc-
tion in whole degrees; 8.0 (SPD) is the surface
wind speed in m/sec; and the directions and
speeds at 150, 300, 600, 900, and 1200 m AGL
are given in the same manner as surface winds.
Continuing with the example for surface-
based inversions, 00000 (at left side of the
third line in Table A-2) is the height (m) of
the inversion base; 00109 is the height of the
inversion top; the second 00109 is the inver-
sion thickness, AZ; 7.8 is the temperature (°C)
at the inversion base; -7.0 is the temperature
at the inversion top; .8 is the temperature at
inversion top minus that at inversion base,
AT; .0073 is AT/AZ (°C/m) through the inversion;
53.2 is the average relative humidity (percent)
through the inversion; .0 at this entry indi-
cates a sounding with a surface-based inver-
sion; 49.4 is the average relative humidity in
the 300-m layer immediately above the inversion
top; .0, .0, and .0000 at their respective
entries indicate a sounding with a surface-
based inversion; and 1 indicates a sounding
with an inversion base in the lower 3 km of the
atmosphere.
Elevated Inversions
The format for elevated inversions is the
same as that for surface-based inversions,
except, as shown in Table A-2, line 6, the
ninth through thir"°enth entries for elevated
inversions are different. 72.8 (Table A-2,
line 6, ninth entry) is the average relative
humidity in the entire layer beneath the
inversion base; .0 at this entry indicates a
sounding with an elevated inversion; 7.9 is the
surface temperature; -11.6 is the inversion
base temperature minus the surface temperature,
AT; and -.0060 is AT/AZ for the entire layer
beneath the inversion base.
No Inversion
For soundings with no inversion in the
lower 3 km, the format for entries through the
1200-m wind speed (Table A-2, lines 7 and 8) is
the same as for soundings with inversions. The
remaining entries for no-inversion soundings
(Table A-2, line 9) are as follows: the first
six entries, -.0033 through -.0079, give values
of AT/AZ (°C/m) for the consecutive layers
1-100, 101-250, 251-500, 501-750, 751-1000,
and 1001-1500 m; the second six entries, 52.5
through 53.5 give average relative humidity
(percent) for each of the same layers as
indicated for AT/AZ; the last two entries, NONE
and 2, designate a sounding with no inversion
in the lower 3 km.
FORMATS OF SUMMARIES OF PROCESSED SOUNDINGS
The processed sounding data were sum-
marized and printed in three formats, one each
for temperature structure, relative humidity,
and winds by temperature structure. The
summaries for each station are by season (Dec,
Jan, Feb = winter; etc.), by total period of
record, and by observation time.
Temperature Structure
Table A-3 is a copy of the summary of
temperature structure characteristics as
measured from Pittsburgh, Pennsylvania
(STATION 94823) during the autumn season (Sept,
Oct, Nov). The time (00) is 0000 GMT, which is
19
-------
the scheduled synoptic observation time; this
means the balloons were actually released about
1815 EST. The period of record, which is given
only on the cover page of the summaries, is the
5 years, 1960-1964. All of the percent fre-
quencies are with respect to the total number
of soundings that were made. Values are
rounded to the nearest tenth of a percent.
Approximately the upper three-fourths of
Table A3 is used to summarize temperature
inversion conditions (i.e., AT/AZ Xl.OOOO
°C/m). It gives the frequency of inversion
base heights (across the top) by inversion
thickness (DELTA HEIGHT) and by classes of
AT/AZ through the inversion layer. These
classes of AT/AZ are specified at the bottom of
the page on the left under DELTA T/H INVERSION
LAYER. Classes A-C each have an angular spread
on an adiabatic diagram of 22.5 deg; classes D
and E each have a spread of 11.25 deg.
Table A-3 indicates that 26.3 percent of
the observations detected a surface-based
inversion; most of these (20.6 percent) had a
thickness of 101-250 m; and for most of the
latter that AT/AZ class was A or B (8.2 percent
each), indicating weak or very weak inversion
intensities. An inversion base within 3000 m
of the surface occurred in 76.6 percent of the
observations. An inversion base above the
surface, but within 3 km of the surface,
occurred in (76.6 minus 26.3) 50.3 percent of
the observations. Elevated inversion bases
occurred most frequently (13.0 percent) in the
range 1001-1500 m, followed closely by the
range 1501-2000 m (12.1 percent).
The next lower one-eighth of Table A-3
(SFC-BASE OF INVER) shows the frequencies of
AT/AZ classes for the entire layer beneath an
inversion base, according to inversion base
height (given near top of page). The
AT/AZ classes for lapse conditions are given at
the bottom of the page under DELTA T/H NO
INVERSION. Notice that class B includes the
standard atmosphere value of AT/AZ = -0.0065
°C/m and class C is centered on the dry adia-
batic rate.
The last one-eighth of Table A-3 (NONE)
is for observations with no inversion in the
lowest 3 km. It gives the frequencies of
AT/AZ classes (DELTA T/H NO INVERSION) for
the same layers as used for inversion base
heights through 1500 m, as indicated at the
top of the summary. In Table A-3 notice that
23.4 percent of the observations (given in
lower right of table) had no inversion in the
lower 3 km. The total frequency of AT/AZ
classes for each specified layer of no-
inversion soundings is therefore 23.4 percent,
allowing for slight deviations due to round-
ing.
In the extreme lower right of Table A-3,
the value .4 indicates that the ratio of
soundings with incomplete temperature data
(e.g., sounding terminated below 3000 m) to
those with sufficient temperature data is
4/1000 or 0.4 percent.
Relative Humidity
Table A4 is a copy of the relative
humidity summary for Pittsburgh, autumn,
0000 GMT soundings. It gives the percent
frequencies (in tenths) by relative humidity
classes (defined at bottom of table) of the
average humidity in certain layers, according
to whether or not a temperature inversion
occurred in the lower 3 km. In Table A-4 the
last line (NONE) is for no-inversion sound-
ings; the average relative humidities are for
the layers indicated at the top of the table
under DELTA HEIGHT. For example, no-inver-
sion soundings with an average relative
humidity of class 2 (40-69 percent) in the
layer 1-100 m occurred in 10.2 percent of the
observations.
The remainder of Table A-4 is for inver-
sion soundings. The percent frequencies of
average relative humidities in the layers
specified at the bottom of the table are
given by inversion base height (left column)
and inversion thickness (DELTA HEIGHT). For
surface-based inversions the average relative
humidities are for the entire inversion layer
(I) and for the 300-m layer immediately above
(A) the inversion top. For elevated inver-
sions the average relative humidities are for
the entire layer below (B) the inversion base
as well as for the inversion layer.
Hinds by Temperature Structure
Table A-5 is a copy of the last part if thf
wind summary for Pittsburgh, autumn, 0000 GUT
20
-------
soundings. The table gives a brief wind rose
(defined at bottom of table) for the surface
each of the levels, 150, 300, ..., 1200 m,
above station elevation, according to whether
soundings included (ALL INVERSIONS) or did not
include (MO INVERSION) an inversion base in the
lower 3 km. The percent frequencies of occur-
rence are given to the nearest tenth and, as
for all summaries, are with respect to the
total number of observations what were taken.
The LINE TOTAL;; i- Tdble A5 are for all wind
levels together and nay 3e intc-rpreted as 3
summary of average yi.id directions for the
1200-m layer. The LINE TOTAL percentages (as
otner subtotals in the summaries) are based on
LINE TOTAL frequency counts with respect to the
grand total frequency count. Thus, the given
LINE TOTAL percentages are more precise than
the sum of percentages on a line divided by six
(i.e., the number of wind levels).
In Table A-5, the last row, MISSING TOTAL,
gives the percent frequency of all missing wind
data for each level with respect to the total
number of observations taken. Missing wind
data are not broken down according to temper-
ature structure.
As mentioned earlier, Table A-5 includes
only the last part of a complete wind summary.
The other parts give wind roses like those in
Table A-5, except they are by classes of
inversion base height and inversion thickness
as follows:
Inversion
Base Height (m)
Surfaca-100
101-250
251-500
501-750
751-1000
1001-3000
Inversion
Thickness (m)
1-100
101-250
251-500
501-750
751-1000
1001-1500
Thus, in addition co the two broad temperature
structure classifications in Tanle A-5, pro-
vision is made for 36 more. However, it is not
unusual for many of the Classifications to have
few or no entries- depending on season, obser-
vation time, and location.
DATA AND AVAILABILITY
All of the data that have been described
were prepared by the National Climatic Center
(NCC) under Job. No. 13105, "Inversion Study,"
and are available from the NCC (Federal Building,
Asheville, N.C. 28801) at the cost of repro-
duction. These data are as follows:
° Listings of processed dat^, for each
sounding are available on magnetic tape
or as hard-copy printout.
0 Summaries in percentage values for
season, to^l period, and each observa-
tion time are available on hard copy.
For one observation time a complete
summary requires 75 pages (10 x 17 3/4
inch), five each for temperature structure
and relative humidity, and 65 for winds
by temperature structure. Summaries in
terms of actual frequency counts can be
prepared when specifically requested.
The stations (and other pertinent infor-
mation) for which soundings have been processed
and summarized to date are listed in Tables A-6
and A-7. Table A-6 is for those stations that
routinely took two soundings every day as part
of the regular upper-air synoptic network. For
these stations, entirely missed soundings or
soundings with incomplete temperature data
(e.g., soundings terminated at. a low level that
precludes complete determination of temperature
structure) were rare. In cases of incomplete
temperature data the last digit of the data
listing for individual soundings (see Table A-2)
is a "3."
Table A-6 includes the same 62 stations
(each for the corresponding period of record,
and for a few additional separate periods) that
were used to develop climatological values of
mixing height and wind speed for the contiguous
United States (Holzworth, 1972). Thus, the
mixing height data and those described herein
supplement each other. Sequential listings of
individual mixing height and wind speed values
for the stations and period of record used by
Holzworth (1972) are available on magnetic tape
from the NCC.
Most of the periods of record indicated in
Table A-6 are for the years 1960-1964. It will
be recalled that 1964 is the last year for
which NWS hourly surface weather observations
were keypunched and published as Local Clima-
tological Data Supplement. Since 1964 only
21
-------
three-hourly observations have been digitized
and published. In recent years, however, NCC
customers have had many of the hourly observa-
tions digitized. 1964 is also the last year
for which winds aloft were routinely digitized
by constant height.
Table A-7 lists those stations that took
soundings in support of air pollution control
activities. Most of the soundings were taken
by NWS teams known as Environmental Meteorolo-
gical Service Units (EMSU). The soundings were
"low-level" because ordinarily they were terminated
at about 3 km above the station. The ascent
rate of the balloons was usually around 2.5 m/sec
or half as fast as routine soundings. The
radiosonde equipment that was used was comparable
to that used for regular synoptic soundings,
except that winds aloft were commonly determined
by tracking the radiosonde balloon with a
theodolite instead of the radio direction
finder used with rawinsondes. Thus, for low-
level soundings the wind observations were
dependent on cloudiness, and in some cases were
sparse and biased.
Low-level soundings were scheduled to be
taken twice daily on regular work days
(i.e., Mon-Fri) and in addition as required
during air pollution episodes (see footnotes
in Table A-7). However, additional soundings
were seldom required and in some cases sched-
uled soundings were not taken due to personnel
limitations. The total number of low-level
soundings may be determined accurately from
summaries in terms of actual frequency counts
In such a case the last point of the sounding
was processed as the inversion top, and in the
data listings for individual soundings
(see Table A-2), was designated by a "4" as the
last digit. Such cases were also summarized
separately in tables (identical to Tables A-3,
A-4, and A-5) denoted at the top by a "T." In
these T-tables the percent frequencies are also
with respect to the total number of observations
that were taken. If copies of the T-tables are
desired, they should be specifically requested.
Since the low-level sounding data were
obtained over a relatively short time period
and did not follow the rigorous requirements of
the regular synoptic sounding program, they were
instead of percent frequencies. Such actual
frequency counts would also be useful in
evaluating those wind summaries with extensive
missing data.
As indicated in Table A-7 the two sounding
times were rather loose; they were usually
around sunrise and noon LST. Both soundings
were taken in one eight-hour shift and thus the
clock times tended to be somewhat earlier in
summer than in winter. In the NCC summaries
listed in Table A-7, the "near-sunrise" sound-
ings are indicated as "01" and the "near noon,"
as "02."
Since the low-level soundings only sampled
the lower 3 km of the atmosphere, a problem
arose in those cases where the last point of a
low-level sounding was the maximum actual
temperature of that sounding (see Section 2).
not considered suitable for analyses with the regu-
lar sounding data, which forms the main body of
this report. However, the low-level sounding
data are described here since they may be very
useful in specific applications.
The NCC is prepared to process and summarize
sounding data in addition to those listed in
Tables A-6 and A-7 at the cost (to the customer)
of computer time and data handling.
22
-------
TABLE A-l.
PHOTOCOPY OF ONE PAGE OF COMPUTER PRINTOUT OF PROCESSED RAWINSONDE MEASUREMENTS THAT ARE
STORED ON MAGNETIC TAPE. FOR DETAILS SEE TABLE 2 AND TEXT.
ST* YK MO DA HI SFC SEP ISO SPO 300 SPD 600 »PD 900 SPD1200 SPO
2115* 6Q 01 03 00 190 1.0 218 1.0 220
81194 60 Ol 0* 00 020 B.O o!5 lO.D 012 1
2113* 6Q 01 09 00 360 2.0 390 3.0 341
21134 «0 01 06 00 020 2.0 009 3.0 001
W1S* 60 01 07 00 180 1.0 187 1.0 197
1119* 60 01 08 00 09Q 4.Q L6o 4,0 206
11134 60 01 09 00 ISO 9.0 174 13.0 171 1
I1IH 60 ol 16 So 1*6 7.0 173 lo.O 167 1
H13* 60 01 11 00 180 8.0 173 9.0 168 1
19* 6Q Ql 12 00 200 9.0 182 7.0 17*
HIS* 60 01 11 00 360 3.0 398 4.0 360
19* 6fl 01 14 00 27o 3*0 3lB 3.0 399
H134 60 01 13 QO ISO 10.0 176 11,0 174 1
11134 60 01 17 OQ 360 4.0 36o 4.0 359
21154 60 OJ 11 00 270 2.0 293 2.0 310
H19* 60 01 19 00 160 2.0 342 1.0 29o
15* 60 01 20 00 110 4.Q 316 3.0 281
21134 60 01 II 00 140 2.0 158 3.0 l7o
23154 6Q 01 22 00 180 S.O iTT 11. 0 1?! 1
194 60 01 2* 00 090 1*0 1*8 1,0 177
11134 60 01 19 no 220 4.0 207 4.0 192
21154 60 01 26 00 130 2.0 164 3.0 20*
HIS* 60 01 17 00 170 4.0 17* 4,0 176
15* 6Q 01 28 00 290 4.0 237 4.Q 263
2113* 60 01 29 00 160 3.0 149 3,0 141
2113* 60 01 10 00 190 2.0 16* 3.0 173
2113* 60 01 11 00 310 6.0 313 6.0 320
1313* 6Q 02 01 00 160 1.0 347 1.0 313
HIS* 60 02 02 00 180 13.0 l72 13.0 163 1
154 60 02 01 00 320 B.o 323 B.O 327
2313* 60 02 04 00 200 4.0 194 4.0 187
11194 6Q 02 05 00 010 3.0 360 3.0 393
23184 60 01 06 Qfl 120 5.0 314 S.O 304
•o zn
.0 35o
.0 010
,0 300
,o 22!
.0 187 1
.0 17Q 1
.0 169 1
.0 181
>0 007
.0 016
.0 1B2
.0 333
,0 289
.0 233
>0 132
.0 l7i
.0 1"! 1
«0 1B0
.0 na
.Q 249
.0 16*
.0 ;BI
.0 123
.0 313
.0 082
.0 173 1
.0 328 1
.0 179
>0 230
.0 306
11154 60 01 07 00 100 2.0 110 2.0 128 .0 292
2J194 60 01 QB 00 IBO 5.0 186 6.0 19* 7.0 212
111!* bfl 01 10 00 220 S.O Z23 3.0 211 4.0 247
aaiB* An 01 12 oo o2o 7. a ol9 7.0 ai6 B.o ois
taii* An ol 14 no Iko 9. a 352 n.n 33A 12.0 33* i
2H«* An ns l* no 2AO 4. a 263 3.0 266 3.Q 269
.1 269
l.O 612 7
.0 009
.0 013
,8 295
.0 246
.0 211 1
.0 193
.0 183 1
.1 201
.0 111
.9 030
.0 192
.0 000
,1 349
,1 307
.1 266
• 0 218
.0 192
.0 2QZ 1
.2 189
.1 270
.0 170
.0 274
.0 037
.0 175
.4 315
.0 196 1
.0 32? 1
,_3 19T
.0 322
.0 309
.0 300
.4 22* 1
.1 255 1
.0 nil i
.0 331 10
.1 n> 1
jaiS* 60 o* 11 on 310 4.0 310 4.0 310 4.O 295 4.O 29* !
4 017 T.3 06068 00»6 »»6 -11. a -11.1
B 012 10.1 00000 00484 004B4 - 9.8 - 7,
3 006 lo.l 00000 003" 00938 - !.! - 1.
5 303 9.3 00000 00111 00111 4.6 4.
B 263 10.3 00000 0010Z 00102 1.7 3.
8 32 16.2 00000 00101 00101 1.6 9.
I
I
'
i
}
3
z
B
i
I
02 10.6 00000 00101 00101 1,1 3.
12 11.2 00000 00101 00101 - 1.7 - 1,
IB 3.7 - .0051 - .00*3 - .009* - .007
95 1.2 00000 00019 00019 - 7,9 - 7.
09 B.6 Q127Q 01733 004 13 -13.9 -lJ.
0 11.8 00000 000'7 ooo97 - 9.J - 8.
B 13.0 - .00** - .0034 - .003* - '003
2 10.1 00250 01102 00832 -12.4 - 9.
7 5.0 01343 oi46n 001(3 - 6.8 - 3.
2 13.3 00000 00616 00616 - .4 .
0 3.0 01972 Q2J21 00249 _ S.4 - 7.
9 B.l . .0048 . .00*0 - .0040 - -00o
2.
1 — ,'Bflii U.4 .1) 3-i.l XI ^ PWOD 1—
.009 17.8 ,0 19,6 .0 >0 .0000 1
.000 ".3 .0 56.0 .0 >0 .0000 1
.Oil 99.8 ,0 90,7 .0 '0 .0000 1
,018 6Q.4 .0 99.3 .0 .0 .0000 1
71 . . 072 79,8 79.1 78.3 77.7 71-.I 76.6 NONE 2
.0000 82.0 73.2 .0 - 9.1 - 8.* . .006* 1
.00*1 94,6 .0 5
,OOB> 76.6* 76,3
.0112 21.5 41.2
- .0097*. .0062 7Q.3 6*.l 3
- .0073 - ,0072 7Q.O 66.* 6
.9 .0090 *8,3 ,0 *
,8 .0071 39, A ,o 9
1,0 .00*5 89.3 83.7
.7 ,o >0 '0000 1
.0 -11. 0 - 1.* - .003* i
.0 .* - 7.2 * .0054 i
.9 ,o *o >doou i
.9 .0 .0 .0000 1
.0 a. a -»•*• - .oo»» i
.1 41.0 19.4 47.Q NONE 1
.1 68,2 70.0 71.8 NONE 2
.8 .0 .0 .0000 1
.6 .0 .0 .0000 ' 1
.0 - .1 - 8*0 * .00*4 1
- .00*2 - ,0030 49.3 41.9 17.0 >0.0 23.0 2t.5 NONE 2
.0 .0060 61.5 63. 0 .0 1.6 -10.3 - .0019 1
2.3 .0228 SJ.Q .0 41.1 .0 .0 .0000 1
1.3 .0063 32.1 IS. 7 .6 6.4 - 1.2 - .0074 1
1. .0126 3*. 7 .0 30.1 .0 .0 .0000 1
- .008* - ,0071 62.6 3»,7 64.4 70.0 75.* 71.0 NONI i
1 OU 10.2 01687 02019 00332 -13.0 -13.0 .0 .OOOO 16.9 46.0 .0 .5 -11.5 - ,0080 1
6 326 11.1 - .0011 - .0096 - .0096 - .009S - .0099 - .0076 33.3 31.0 98.0 64.6 71.5 79,7 NONE 2
1 233 9.0 - .0238 - .0088 . .0094 - .0096 . .0100 - .0099 31.0 32.7 15.7 Jt.6 U.I *8.6 NONE 2
8 295 8.4 01798 0206S 00267 -12.0 -10.6 1.4 .OO32 *3.o 17,6 .0 4,0 -16,0 - .008* I
23
-------
TABLE A-2. EXAMPLES OF THE THREE FORMATS USED TO STORE PROCFSSED RAWINSONDE DATA ON MAGNETIC TAPE. ON A
PAGE OF ACTUAL PRINTOUT THE HEADING (LINE 1) IS NOT REPEATED (LINES 457) AND ALL THE DATA
FOR A SOUNDING ARE ON ONE LINE. SEE TEXT FOR DETAILS.
STA YR MO DA HR SFC SPD 150 SPD 300 SPD 600 SPD 900 SPD1200 SPD
uul 23066 60 02 18 12 120 8.0 128 10,0 135 11.0 151 9.4 175 7.0 199 6.3
c
00000 00109 00109 - 7.8 - 7.0 .8 .0073 53.2 .0 49.4 .0 .0 .0000 1
STA YR MO DA HR SFC SPD 150 SPD 300 SPD 600 SPD 900 SPOT200 SPD
a! 23066 60 10 20 12 115 4.0 119 2.0 110 1.0 028 1.0 341 1.
C
1.7 315 3.4 -^v
01943 02169 00226 - 3.7 - 2.2 1.5 .0066 55.0 72.8 .0 7,9 -11.6 - .0060 1
STA YR MO DA HR SFC SPD 150 SPD 300 SPD 600 SPD 900 SPD1200 SPD
o 23066 60 02 19 12 105 5.0 118 6.0 143 7.0 168 7.5 175 9.8 184 11.2
c
.0033 - .0034 - .0034 - .0036 - .0073 - .0079 52.5 51.3 49.4 47.4 46.7 53.5 NONE 2
-------
TABLE A-3. PHOTOCOPY OF HARD-COPY SUMMARY OF TEMPERATURE STRUCTURE CHARACTERISTICS, BASED ON PROCESSED
SOUNDING DATA. SEE TEXT FOR DETAILS.
ITATION 34121 TtHt 00 SIAMN Of-11
OILTA
HlloHT IJIIAC1 1- 100 101- 190 111- 900
1- 100
101- 130
101- 730
1001-1300
»UW
TOTAL
!IC-IMI
or INVIP.
NONI
.1 - ~ -.T-
1.1 .1
I.I .1
••1 ' .2
*.l ,7
•* .1 .7
.2
.1
.*
Pl« CINT TEHPIUTUP.
•ASI OP INVERSION
PMO.UINCY OP OCCUKP.INCI 4
.T
.2
. .*
1.1
. .7
•*
.1
,1
.1 .2
.X
.2
.2 .2 .2
.1
2.0 1.1 1.1 .*
1.1 t.l .1 .*
1.3 .7 .2 .7
.* .* .2 .*
.1 .1
.f .2
2.6
.*
1.1
!i
11.0
10.6
3.1
1.1
l>*
I.Z
.7
2.0
.1
,1 *I
26.1 1 1 •
«
1 1
11 1 7
62 7 91
D '
E * .1
ftUND TOTAL
OILTA t/fi INVASION LAVE*
A 0.0000 - 0.00*7 C/M 0 0.0211 . 0.0600
C 0.0113 - 0.0212 C/H
1 1 9.7
2 0 1.1
7 1.1
1 2 7.1
A <0.0000 TO
1 -0.00*1 TO
C -0.0011 TO
11. 0 11.1 6.* 9.1
6.6 6.0 I.I *.2
2.0
1.1
-0.00*0 0 -0.0121 TO -0.0160
-0.0080 E < -0.0160
-0.0120
76,6
1.1
21. f
• 1
13. »
100,0
.*
25
-------
TABLE A-4.
PHOTOCOPY OF HARD-COPY SUMMARY OF RELATIVE HUMIDITY CHARACTERISTICS, BASED ON PROCESSED
SOUNDING DATA. PERCENTAGE FREQUENCIES ARE IN TENTHS. SEE TEXT FOR DETAILS.
STATION 94921
SURFACE
I- 100
101. lie
251. 900
501.. 7)0
751-1000
looi-UoO
1301.2000
2001.2900
2S01.9000
TOTAL
NONE
B1AMO TOT
MUSING
III 4TTVI k
1 <
2 AOB TO
t TO* TO
A >
t
A"
?
1
t
t
I
1
I
1
i
1
i
9
t
I
I
9
I
9
I
9
lima
40*
69*
99*
991
TtHE 00 SEASON 09-11
1-100
RH
1 19
T 11
t f 2
171
2 2
2. 2
2
2
2
2
2
2
2
2
7 11 *
2 11 t
20 102 90
JTV
101.250
RH
35
54
2
2 2
2
7
29
2
2 7
2 2
7
2 2
7 117
7 T
31 22
124
102
2
I
4
7
11
9
24
51
If
2*
15
JO
4
219
119
95
20
19
2
4
4
4
2
2
U
M
u
u
99
44
9*
4
4
2
2
i
2
2
2
7
T
19
11
20
• -. - -
FER CENT RELATIVE HUHIOtTY FM8UINCY OF OCCURRENCE 9
OElTA HEIGHT
251-500 501-730 791-1000 1001-1900 AND
RH RH RH >1900 RH LINE
I
2
4
2
T
9
if
2
4
t
2
51
20
22
20
,
*
T
4
.11
22
12
|4
20
7
11
9
91
56
It
4 14 11
4 74
2 I
2 2
24 2
24 2
2 224
2 4 4
422 4 4
7 14 2 i
42T48 4 T I
15 2 9 4 4 27
11 4 9 24 2
20 11 2 7 2
2 4 2
2 22 2
4 22
19 2 2
11 9 13 20 t 2 li 11 2 iJ 7 2
66 7 22 11 7 15 4 7 19
104 22 9 96 111 Z4 9 71 124 24 11 62 111 27
TDTAk »l*»
261
161
11
1*
14
24
11
19
95
31
111
111
122
ill
64
64
91
Jl
7»9
504
212
1000
7
I • IN INVERSION LAYER
1 . A10VI INV1IS1GN LAVIR
1 * 9ILDK
INVERSION LAYER
26
-------
TABLE A-5. PHOTOCOPY OF PART OF HARD-COPY SUMMARY OF WINDS BY TEMPERATURE STRUCTURE, BASED ON
PROCESSED SOUNDING DATA. SEE TEXT FOR DETAILS.
17ATIOK t4!21 TIME 00 SEASON Ot-11
HI CINT HIM HHUIHCY OF OCCUMINCI
NO INVIM10N
HII9HT
N "
1
I
*
SUMAC! 1ION 100M BOOH
1 11 7 J— IB 7 J 11 It 1 I 11 21 7
11 2» 1 It T 9 7 14 I I 2 11 1
11 71 14 l |4 II » 14 90 M 11 41 91
voon noon LINB
9 1 21 7 1 7 14 11 l(
1 72 22 11
I 11 12 71 9 20 10 ?1 117
C
NO INVIft"
IIDN TOTAL
47 191 11 21 »• 101 f 11 91 110 97 t 41 t4 17
It 21 10 110 It 31 t4 129 211
ALL INVII1ION1
N
E
,
W
C It
ALL imil-
IIDNI TOTL !•
GUANO
TOTAL
HII9INO
ToTi"
IPltD
C < 00.1
1 00.1 - 01.9
f01ft - 09.0
01.1 - 10.0
4 > 10.0
TMl !UI«»rf. 1SOK.
to 10* It 21 tt 99 li 7> 91 21 21 97 41 12
91 64 21 »» 11 11 91 It 11 21 10 7
47 124 11 21 17 11 2 21 99 »1 t2 21 51 4t t7
71 197 2t 11 12t lot 21 7 71 191 to It 71 144 117
9
1000 1000 1000 1000
f 44 44 44
OHKC7ION
H/9CC N llt-041
M/SEC E 04t*115
H/JEC i 1J4-225
H/1EC W 224-J19
H/IEC C CALM
AND aoOH HINDI 111 OMEIVID WINDS
11 90 99 II 14 It 92 It Itf
7 21 21 t 11 21 11 7 tl
11 4t 41 4t ' It 41 >t 171
t 6T 147 Itl 27 tl 171 170 lit
1
1000 1000 1000
44 14 IB
27
-------
TABLE A-6. NATIONAL WEATHER SERVICE STATIONS FOR WHICH RAWIMSONDE OBSERVATIONS AT SCHEDULED
SYNOPTIC TIMES OF 0000 AND 1200 GMT HAVE BEEN PROCESSED AND SUMMARIZED. SUPER-
SCRIPT LETTERS ON WBAN NUMBERS REFER TO FOOTNOTES AT END OF TABLE.
CITY
Albany, NY
Albuquerque, NM
Amarillo, TX
Anchorage, AK
Annette, AK
Athens, GA
Barter Island, AK
Bismark, ND
Boise, ID
Brownsville, TX
Buffalo, NY
Burwood, LA
Cape Hatteras, NC
Caribou, ME
Cnarleston, SC
Columbia, MO
Dayton, OH
Denver, CO
Denver, CO
Dodge City, KS
tl Paso, TX
tly, NV
Fairbanks, AK
Flint, MI
Fort Worth, TX
WBAN
N0_._
14735
23050
23047
26409
25308
13873
27401
24011
24131
12919
14733
12863
93729
14607
13880
13983
13840s
23062
23062
13985
23044
23154
26411
14826
13911b
PERIOD
SUMMARIZED
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/61-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
07/71-06/72
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
cm
Glasgow, MT
Grand Junction, CO
Great Falls, MT
Green Bay, WI
Greensboro, NC
Hilo, HI
Huntington, WV
International Falls, MN
Jackson, MS
Jacksonville, FL
Lake Charles, LA
Lander, WY
Las Vegas, NV
Lihue, HI
Little Rock, AR
Medford, OR
Miami, FL
Midland, TX
Montgomery, AL
Nantucket, MA
Nashville, TN
New York, NY
Nome, AK
North Platte, NE
Oakland, CA
WBAN
NO.
94008
23066
24143
14898
13723
21504
03860
14918
13956
13889
03937
24021
23169
22536
13963
24225
12839
23023
13895
14756
13897
94789C
26617
24023
23230
PERIOD
SUMMARIZED
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/62-12/64
01/60-12/64
01/59-12/62
01/60-12/64
01/62-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
28
-------
TABLE 6. (Continued)
CITY
Oklahoma City, OK
Omaha, NE
Peoria, IL
Pittsburgh, PA
Pittsburgh, PA
Point Barrow, AK
Portland, ME
Rapid City, SD
St. Cloud, MN
Salem, OR
Salt Lake City, UT
San Antonio, TX
San Diego, CA
San Juan, PR
Santa Monica, CA
Sault Ste. Marie, MI
Seattle, WA
Shreveport, LA
Spokane, WA
Tampa, FL
Tatoosh Island, WA
Topeka, KS
Tucson, AZ
Wallops Island, VA
Washington, DC
WBAN
N0._
13967d
94918
14842
94823
94823
27502
14764
24090
14926
24232
24127
12921
03131
11641
93197
14847
24233
13957
24157
12842
24240
13996
23160
93739
93734e
PERIOD
SUMMARIZED
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/72-12/72
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/59-12/61
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
01/60-12/64
07/70-12/72
01/61-12/64
CITY
Washington, DC
Winnemucca, NV
Wins low, AZ
Yakutat, AK
WBAN PERIOD
NO. SUMMARIZED
93734e 07/70-06/72
24128 01/60-12/64
23194 01/62-12/64
25339 01/60-12/64
FOOTNOTES
a. WBAN No. 13840 is for the rawinsonde sight at
Sulphur Grove. In table A-l of AP-101 (Holzworth,
1972) WBAN No. 93815 is for Cox-Dayton Airport,
about 10 km from Sulphur Grove.
b. Soundings made from Carswell Air Force Base.
c. Soundings made from Kennedy Airport.
d. In table A-l of AP-101 (Holzworth, 1972) the
correct WBAN No. for Oklahoma City should be 13967.
e. Soundings made from Dulles Airport.
29
-------
TABLE A-7. NATIONAL WEATHER SERVICE STATIONS FOR WHICH LOW-LEVEL RADIOSONDE OBSERVATIONS HAVE BEEN PROCESSED AND SUMMARIZED.
CITY
Birmingham, AL
Boston, MA
Charleston, wV
Cnicago, IL
Cleveland, OH
Denver, CO
Detroit, MI
El Monte, CA
Houston, TX
Los Angeles, CA
Louisville, KY
New York, NY
Philadelphia, PA
Pittsburgh, PA
Portland, OR
San Jose, CA
Seattle, WA
St. Louis, MO
Washington, DC
WBAN
NO.
L0180
L0120
L0170
L0020
L0060
L0080
L0160a
L0090
LOlSOb
L0100C
L0070
L0040
L0050
L0150
L0190,
LOIIO"
L0140
LOO 10
LOO 30
LAT
33°34'
42°2T
38° 23'
41°47'
41°30'
39°47'
42°19'
34°05'
29°46'
33° 56'
38°12'
40°46'
39°53'
40°25'
45°32'
37°19'
47°39'
38° 37'
38° 5V
LONG
086° 45'
071°05'
081 °46'
087°45'
081 °36'
104°59'
Q83°13'
118°02'
095°22'
118023'
085°45'
073°54'
075°1T
079°59'
122°41
121°52'
122°18
090° 11'
077°02'
ELEV
M_
0190
0030
0182
0188
0217
1576
0187
0091
0017
0034
0141
0013
0005
0224
0042
0032
0008
0139
0023
PERIOD SUMMARIZED
08/01/72-12/28/73
08/24/71-04/26/73
07/27/72-12/28/73
04/14/69-12/31/73
04/01/71-03/27/73
07/01/71-06/30/72
07/03/72-02/27/73
04/01/71-12/28/73
08/16/71-12/28/73
05/01/71-12/31/73
04/29/71-06/15/73
07/01/70-06/12/72
06/27/69-12/28/73
01/03/72-12/29/72
10/30/72-06/18/73
08/30/71-06/08/73
10/18/71-06/29/73
04/16/69-04/27/73
07/01/70-06/30/72
APPROXIMATE TIMES
BALLOONS RELEASED
sunrise ± 1/2 hr & noon LST
sunrise ± 1/2 hr & 1245 LST ± 1/2 hr
0600-0700 & 1100-1200 EST
0620 & 1000 EST
sunrise + 1/2 hr & noon LST
sunrise ± 1/2 hr & noon LST
about 0700 & 1200 EST
about 0600 & 1300 PST
near sunrise & noon LST
0530 & 1230 PST
near sunrise & noon LST
0600-0700 & 1100-1200 EST
sunrise ± 1/2 hr & noon LST
sunrise ± 1/2 hr & 1200 LST
about 0620 & 1240 LST or DST
0530 & 1130 LT
0545 4 1115 PST
sunrise ± 1/2 hr & noon LST
sunrise - 1/2 hr & 1215 LST
RELEASE SITE
Eastern edge Municipal Airport
International Airport
West Virginia State College campus
Midway Airport
Case Western Reserve Univ campus
Just south of Coliseum
Univ Michigan (Park lot E) Dearborn
Northeast corner El Monte Airport
1/2 mi northwest of downtown
International Airport
Univ Louisville campus
La Guardia Airport
US Army Quartermaster Depot
South 6th St & Monongahela Riv
Roof of Federal Bldg downtown
San Jose State Univ campus
Just south of Univ of Washington
Gateway Arch
National Airport, main terminal
a. 1200 EST soundings extended through 03/28/73.
b. Noon soundings sparse since 05/08/73.
c. Soundings made every day.
d. 1130 LT soundings ended 03/16/73.
30
-------
E
^
K
X
LU
I
TEMPERATURE
Figure 1 Objective scheme for specifying base and top of inversions for various temperature profile configurations.
31
-------
"*« tTATOOlH ISLAND
»4om + GLASGOW
24^SEATTLE "'"^SPOKANE 24141 + GREAT FALLS
••" 1/59-12/81
14919 4\ ^
INTERNATIONAL FALLS
24011 » BISMARCK
14141+SAULT ST. MARIE
"807 ,, CARIBOU
|«2«+ST. CLOUD
241S1+BOISE
2.4010 + RAPID CITY
'«•• SCREEN BAY
'""iPORTLAND
»«»«-fMEDFORD
* LANDER
1/61-12/64
241M+WINNEMUCCA 241W+ SALT LAKE CITY
211S4 + EIY
2JW2 +DENyER
JM,« + 1/60-12/64
GRAND JUNCTION 7/71-6/72
"VoPEKA '38I3''COLUMBIA
B\ OAKLAND
mis + DODGE CITY
HAWAII
14142 +pEOR|A »«2»+f>ITTSBURGH
11140 + nflVTnN 1/61-12/64
+ DAYTON 1/72.,2/72
"13< 4-WASHIMGTON
"•» +HUNTINGJON 1/61J2/64J/70-6/72
1/62-12/64 «^M 41WALLOPS ISLAND
, • . 7/70-12/72
"»«' + NASHVILLE '«'» +GREENSBORO,*',
J«n*NANTUCKET
NEW YORK
SANTA
MONICA
05131 + SAN DIEGO
WINSLOW ALBUQUERQUE AMARILLO
1/62-12/64
13SS1+OKLAHOMACITY
«•«+ LITTLE ROCK
»'»*TUSCON jM^^p^
19111 +
FT. WORTH
SHREVEPORT
1/59-12/62.
»" tLAKE CHARLES
+SAN ANTONIO '1/62-12/64'".
'""^ATHENS
tmo^ CHARLESTON
* MONTGOMERY
'""* JACKSONVILLE
12911 ^ BROWNSVILLE
ANNETTE
2HM +
YAKUTAT
2140* +
ANCHORAGE
ALASKA
21411 +
FAIRBANKS
21111 +
NOME
null +
BARTER ISLAND
21(12 »
BARROW
PUERTO RICO
11B41 +
SAN JUAN
Figure 2. The 76 rawinsonde locations and their WBAN numbers used in this study. Dates indicate observational period(s) at those sta-
tions where it was other than 1/60-12/64. San Diego is plotted about 250 km south of its true location to avoid overprinting. Stations
outside the contiguous United States are plotted along the periphery.
32
-------
•si,
+
-83.4°
-79.2°
-40°
-35°
-15"
-10°
-473° -47.2° -48.4° -44.7°
-46.7°
-39.2°
-39.5°
+2.5"
Figure 3 Angles of solar elevation on January 15 at 1115 GMT Negative angles indicate that the sun is below the horizon. See Figure 2
to identify peripheral stations.
33
-------
-57.1
-57.7
-25°
-20°
-15
5°
10°
-18.3°
-17.1°
-17.7°
-13.9° -15.9°
-8.4°
-8.6°
+14.9°
Figure 4. Angles of solar elevation on April 15 at 1115 GMT. Negative angles indicate that the sun is below the horizon. See Figure 2 to
identify peripheral stations.
-------
Figure 5 Angles of solar elevation on July 15 at 1115 GMT Negative angles indicate that the sun is below the horizon See Figure 2 to
identify peripheral stations
35
-------
-71.4°
-69.7
-35°
-30
-33.Z0
-33.2° -34.6
-30.9"
-33.6°
+
-Z5.50
-26.2°
+12.6°
Figures. Angles of solar elevation on October 15at 1115GMT. Negative angles indicate that the sun is below the horizon. See Figure 2
to identify peripheral stations.
36
-------
46.3
47.7'
15'
8.3°
6.4°
6.6° 2.9°
4.4°
-2.7°
-15.8°
Figure 7 Angles of solar elevation on January 15 at 2315 GMT Negative angles indicate that the sun is below the horizon See Figure 2
to identify peripheral stations.
-------
7A.8°
73.4°
36.1°
35.7°
36.8° 33.0°
35.2°
27.6° 28.0°
-8.7°
Figure 8 Angles of solar elevation on April 15 at 2315 GMT. Negative angles indicate that the sun is below the horizon. See Figure 2 to
identify peripheral stations.
38
-------
82.6°
78.4°
35°
30
47.2°
47.3°
48.6°
44.9°
47.0°
39.4° 39.8°
-3.1°
Figure 9 Angles of solar elevation on July 15 at 2315 GMT Negative angles indicate that the sun is below the horizon See Figure 2 to
identify peripheral stations.
39
-------
57.0°
20°
15'
-15°
17.9°
17.1°
78.1°
14.4°
16.8°
8.9°
9.4°
-18.1°
Figure 10. Angles of solar elevation on October 15 at 2315 GMT. Negative angles indicate that the sun is below the horizon. See Figure
2 to identify peripheral stations.
40
-------
80
^ ^
Figure 11. Percentage of all 1115 GMT soundings with a surface-based or elevated inversion below 3000 m AGL. See Figure 2 to identify
peripheral stations.
-------
Figure 12. Percentage of winter 2315 GMT soundings with a surface-based or elevated inversion below 3000 m. See Figure 2 to identify
peripheral stations.
42
-------
40
80
Figure 13. Percentage of spring 2315 GMT soundings with a surface-based or elevated inversion below 3000 m. See Figure 2 to identify
Peripheral stations.
-------
60 SO 40
30
70
Figure 14. Percentage of summer 2315 GMT soundings with a surface-based or elevated inversion below 3000 m. See Figure 2 to identify
peripheral stations.
-------
6D
90
l_
Figure 15 Percentage of autumn 2315 GMT soundings with a surface-based or elevated inversion below 3000 m See Figure 2 to identify
peripheral stations.
45
-------
50 60
50
•0+31 M + 19
Figure 16. Percentage of winter 1115 GMT soundings with a surface-based inversion. Elevated inversion frequency is at right.
See Figure 2 to identify peripheral stations.
46
-------
30 40 50 60
L_
Figure 17 Percentage of spring 1115 GMT soundings with a surface-based inversion. Elevated inversion frequency is at right.
See Figure 2 to identify peripheral stations.
<*7
-------
30
50
Figure 18. Percentage of summer 1115 GMT soundings with a surface-based inversion. Elevated inversion frequency is at right.
See Figure 2 to identify peripheral stations.
48
-------
50 60 70
70
Figure 19. Percentage of autumn 1115 GMT soundings with a surface-based inversion. Elevated inversion frequency is at right
See Figure 2 to identify peripheral stations
-------
20
30
30 20
Figure 20. Percentage of winter 2315 GMT soundings with a surface-based inversion. Elevated inversion frequency is at right
See Figure 2 to identify peripheral stations.
50
-------
;*> 3«
Figure 21 Percentage of spring 2315 GMT soundings with a surface-based inversion. Elevated inversion frequency is at right.
See Figure 2 to identify peripheral stations.
51
-------
Figure 22. Percentage of summer 2315 GMT soundings with a surface-based inversion. Elevated inversion frequency is at right.
See Figure 2 to identify peripheral stations.
52
-------
10
,
Figure 23. Percentage of autumn 2315 GMT soundings with a surface-based inversion. Elevated inversion frequency is at right.
_ See Figure 2 to identify peripheral stations.
53
-------
30
20
34 -+30 6S+ 10
Figure 24. Percentage of winter 1115 GMT soundings with an elevated inversion below 3000 m AGL. Surface-based inversion frequency is at left.
See Fiqure 2 to identify peripheral stations.
-------
20 30
50 I 10
30
Figure 25 Percentage of spring 1115 GMT soundings with an elevated inversion below 3000 m AGL Surface-based inversion frequency is at left.
See Figure 2 to identify peripheral stations
-------
40 30 20
80
Figure 26. Percentage of summer 1115 GMT soundings with an elevated inversion below 3000 m AGL. Surface-based inversion frequency is at left.
See Figure 2 to identify peripheral stations.
56
-------
20
91+23 94 + 7
Figure 27 Percentage of autumn 1115 GMT soundings with an elevated inversion below 3000 m AGL. Surface-based inversion frequency is at left.
See Figure 2 to identify peripheral stations
57
-------
Figure 28. Percentage of winter 2315 GMT soundings with an elevated inversion below 3000 m AGL. Surface-based inversion frequency is at left.
See Figure 2 to identify peripheral stations.
58
-------
30
Figure 29 Percentage of spring 2315 GMT soundings with an elevated inversion below 3000 m AGL. Surface-based inversion frequency is at left.
See Figure 2 to identify peripheral stations.
59
-------
50 40
30
"t-
40
Figure 30. Percentage of summer 2315 GMT soundings with an elevated inversion below 3000 m AGL Surface-based inversion frequency is at left.
See Figure 2 to identify peripheral stations.
60
-------
4Q 50 50
40
Figure 31. Percentage of autumn 2315 GMT soundings with an elevated inversion below 3000 m AGL Surface-based inversion frequency is at left.
See Figure 2 to identify peripheral stations
6!
-------
10 20
30 40 50
50
••-*fx«, .,
30
y W
£.
,/u •,„ - „. /
^ "' S /
- iT*"' '/
' s s ?n '
JS/40
"+ sj
Figure 32. Percentage of winter 1115 GMT soundings with a surface-based inversion (left) whose top exceeds 100, 250, 500, 750, 1000,
or 1500 m AGL (right, bottom to top), isopleths show the percentage with tops that exceed 250 m. See Figure 2 to identify
| peripheral stations.
62
-------
10 20 30
30
30
X
10
"1!
Figure 33 Percentage of spring 1115 GMT soundings with a surface based inversion (left) whose top exceeds 100, 250, 500, 750, 1000,
or 1500 m AGL (right, bottom to top) Isopleths show the percentage with tops that exceed 250 m. See Figure 2 to identify
peripheral stations
63
-------
30
50 -c,...
r^V^ :
Qk 20 a
,Sio
«+ IS
Figure 34. Percentage of summer 1115 GMT soundings with a surface-based inversion (left) whose top exceeds 100, 250, 500, 750, 1000,
or 1500 m AGL (right, bottom to top). Isopleths show the percentage with tops that exceed 250 m. See Figure 2 to identify
peripheral stations.
-------
Figure 35 Percentage of autumn 1115 GMT soundings with a surface-based inversion (left) whose top exceeds 100, 250, 500, 750, 1000,
or 1500 m AGL (right, bottom to top) Isopleths show the percentage with tops that exceed 250 m See Figure 2 to identify
peripheral stations.
65
-------
l*Tr
5 »V,'i •*Sj--'--\
- ' ^ '
\ /""' ""J
"• l *
t
1
: : • i? i ! A
3 + J 14 + * 16 + 28 + [I " + 12 92+ It 3Q+ 80
i .2 : u H r, is
-K
; o
_' / i
Figure 36 Percentage of all 2315 GMT soundings with a surface-based inversion (left) whose top exceeds 100, 250, 500, 750, 1000,
or 1500 m AGL (right, bottom to top). Isopleths show the percentage with tops that exceed 250 m. See Figure 2 to identify
peripheral stations
66
-------
•••{
1Q->>
\
•y\
Figure 37 Percentage of all 1115 GMT soundings with an elevated inversion base in the range 1-3000 m AGL (left) and in smaller ranges
1-250, 251 500, 501-750, 751-1000, 1001-2000, or 2001-3000 m AGL (right, bottom to top). Isopleths show the percentage with bases
between 1001-2000 m See Figure 2 to identify peripheral stations.
67
-------
Figure 38 Percentage of winter 2315 GMT soundings with an elevated inversion base in the range 1-3000 m AGL (left) and in smaller
ranges 1-250, 251-500, 501-750, 751-1000, 1001-2000, or"2001-3000 m AGL (right, bottom to top). Isopleths show the percentage with
bases between 1001-2000 m. See Figure 2 to identify peripheral stations.
68
-------
,20
Figure 39 Percentage of spring 2315 GMT soundings with an elevated inversion base in the range 1-3000 m AGL (left) and in smaller
ranges 1-250, 251 500, 501-750, 751-1000, 1001-2000, or 2001 3000 m AGL (right, bottom to top). Isopleths show the percentage
with bases between 1001-2000 m See Figure 2 to identify peripheral stations
69
-------
Figure 40. Percentage of summer 2315 GMT soundings with an elevated inversion base in the range 1-3000 m AGL (left) and in smaller
ranges 1-250, 251-500, 501-750, 751-1000, 1001-2000, or 2001-3000 m AGL (right, bottom to top) Isopleths show the percentage
with bases between 1001-2000 m. See Figure 2 to identify peripheral stations.
70
-------
20
Figure 41. Percentage of autumn 2315 GMT soundings with an elevated inversion base in the range 1-3000 m AGL (left) and in smaller
ranges 1-250, 251 500, 501-750, 751-1000, 1001-2000, or 2001 3000 m AGL (right, bottom to top) Isopleths show the percentage
with bases between 1001-2000 m. See Figure 2 to identify peripheral stations
71
-------
io
48 + • '•**
10
H+ J
10.
.<• j
28
R
Figure 42 Percentage of winter 1115 GMT soundings with an elevated inversion base within 3000 m AGL (left), and a thickness
exceeding 100, 250, 500, 750,1000,or 1500 m (right, bottom to top). Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
72
-------
"*ii
Figure 43 Percentage of spring 1115 GMT soundings with an elevated inversion base within 3000 m AGL (left), and a thickness
exceeding 100, 250, 500, 750, 1000, or 1500 m (right, bottom to top). Isopleths show the percentage with thicknesses exceeding 500 m
See Figure 2 to identify peripheral stations.
73
-------
T»-
•\M
\, / *' 20
/ *
10 r~->,
! ^
,'««+ I
•"'+ "3
J -
\ a
«'+ "i
«+ J 10+ ; ••-,
Mi ,5
•
t+ i /'* J "+ ' ••
\ " j1 " <* !
• t
•3 «+H
« a
Figure 44 Percentage of summer 1115 GMT soundings with an elevated inversion base within 3000 m AGL (left), and a thickness
exceeding 100, 250, 500, 750, 1000, or 1500 m (right, bottom to top). Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
-------
V
: \
Figure 45 Percentage of autumn 1115 GMT soundings with an elevated inversion base within 3000 m AGL (left), and a thickness
exceeding 100, 250, 500, 750, 1000, or 1500 m (right, bottom to top) Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations
75
-------
is/
20
"+JI
90
Figure 46. Percentage of winter 2315 GMT soundings with an elevated inversion base within 3000 m AGL (left), and a thickness
exceeding 100, 250, 500, 750, 1000, or 1500 m (right, bottom to top). Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
76
-------
-*-:. -'-i
" B
0 . • 1
• 2 2 4
30 + } 32 + | SO + | M + II
13 IS 24 M
•56 2» 46 SC
/" ,;•• ' Va '; •" \
/ r •« .*» i \
1fl< > 10 *jj \
-/ 5 5 .«
20 ~"-*--ts ' ,11+ ;
S) '—/ n
«i ^ ^ ii
5 ,! t!
••+« 81+?S 1l+K
« 71 10
63 19 "H
0
«+ \
H
44
Figure 47. Percentage of spring 2315 GMT soundings with an elevated inversion base within 3000 m AGL (left}, and a thickness
exceeding 100, 250, 500, 750, 1000, or 1500 m (right, bottom to top) Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations
77
-------
'.If
" \
«+ I
W+ I -3*-+ *4
Figure 48 Percentage o< summer 2315 GMT soundings with an elevated inversion base within 3000 m AGL (left), and a thickness
exceeding 100, 250, 500, 750, 1000, or 1500 m (right, bottom to top) Isopleths show the percentage with thicknesses exceeding 500 m.
See Figure 2 to identify peripheral stations.
78
-------
n+ •
il
Figure 49 Percentage of autumn 2315 GMT soundings with an elevated inversion base within 3000 m AGL (left), and a thickness
exceeding 100, 250, 500, 750, 1000, or 1500 m (right, bottom to top) Isopleths show the percentage with thicknesses exceeding 500 m
See Figure 2 to identify peripheral stations
79
-------
10
V
10
20
il*
u
Figure 50. Percentage of winter 1115 GMT soundings with a surface-based inversion and a thickness of 500 m or less (left), or greater
than 500 m (right) with a AT/AH of 0-0 47, 0.48-1.14, 1.15-2.82, 2.83-6.00, or >6.0 °C/100 m (bottom to top) Isopleths are for a thick-
ness of 500 m or less and a AT/AH of 1.15-2.82 °C/100 m See Figure 2 to identify peripheral stations
80
-------
i :
16 Q
18 •+• 1
U
! 20
Figure 51 Percentage of spring 1115 GMT soundings with a surface-based inversion and a thickness of 500 m or less (left) or greater
than 500 m (right) with a AT/AH of 0-0 47, 048-1 14 1.15-2 82, 2.83-6.00, or > 6 0°C/100m (bottom to top). Isopleths are for a
thickness of 500 m or less and a AT/AH of 1 15-2.82 "C/100 m. See Figure 2 to identify peripheral stations
81
-------
B 0
n
Figure 52 Percentage of summer 1115 GMT soundings with a surface-based inversion and a thickness of 500 m or less (left) or greater
than 500 m (right) with a AT/AH of 0-0.47, 0.48-1.14, 1.15-2.82, 2.83-6.00, or > 6.0 °C/100 m (bottom to top). Isopleths are for a
thickness of 500 m or less and a AT/AH of 1.15-2.82 °C/100m. See Figure 2 to identify peripheral stations.
82
-------
r s
i? s
Figure 53 Percentage of autumn 1115 GMT soundings with a surface-based inversion and a thickness of 500 m or less (left) or greater
than 500m (right) with a AT/AH of 0-0 47,0 48-1.14, 1 15-2 82, 283-6 00, or > 6.0 °C/100 m (bottom to top) Isopleths are for a
thickness of 500 m or less and a AT/AH of 1 15-2.82 "C/100 m See Figure 2 to identify peripheral stations
83
-------
r i
s* -i
: 5
.' 8
!+ 0
Y!
* 0
N
s s
^10,
,i/i y
'j/-,
Figure 54. Percentage of all 2315 GMT soundings with a surface-based inversion having a thickness of 500 m or less (left) or greater than
500m (right) with a AT/AH of 0-0.47, 0.48-1.14, 1.15-2.82, 2.83-6.00 or > 6.0 °C/100 m (bottom to top). I sopleths are for a thickness
of 500 m or less and a AT/AH of 1 15-2.82 °C/100 m. See Figure 2 to identify peripheral stations.
-------
* s
i :
Figure 55 Percentage of all 1115 GMT soundings with an elevated inversion base below 3000 m AGL, and a thickness of 500 m or less
(left) or greater than 500 m (right) with a AT/AH of 0-0 47, 0 48-1 14, 1 15-2 82, 2 83-6 00, or > 6.0 °C/100 m (bottom to top) Iso-
pleths are for a thickness of 500 m or less and a AT/AH of 0 48-1 14 °C/100 m See Figure 2 to identify the peripheral stations
85
-------
1 0
B + 1
L:
Figure 56. Percentage of winter 2315 GMT soundings with an elevated inversion base within 3000 m AGL, and a thickness of 500 m or
less (left) or greater than 500 m (right) with a AT/AH of 0-0.47, 0.48-1.14, 1.15-2.82, 2.83-6.00, or > 6.0 °C/100 m (bottom to top). Iso-
pleths are fora thickness of 500 m or less and a AT/AH of 048-1.14 °C/100 m. See Figure 2 to identify the peripheral stations.
86
-------
Figure 57 Percentage of spring 2315 GMT soundings with an elevated inversion base within 3000 m AGL, and a thickness of 500 m or
less (left) or greater than 500 m fright) with a AT/AH of 0-0 47, 048-1 14, 1 15-2 82, 2.83-6 00, or > 6 0 °C/100 m (bottom to top). Iso-
pleths are for a thickness of 500 m or less and a AT/AH of 0 48-1 14 °C/100 m See Figure 2 to identify the peripheral stations
-------
ITi
•M
8
* 0
9 0
5+ 8
! 8
11+ S
i 11
Figure 58. Percentage of summer 2315 GMT soundings with an elevated inversion base within 3000 m AGL, and a thickness of 500 m
or less (left) or greater than 500m (right) with a AT/AH of 0-0.47, 0.48-1.14, 1.15-2.82, 283-6.00, or > 6.0 °C/100 m (bottom to top).
Isopleths are for a thickness of 500 m or less and a AT/AH of 0 48-1 14 °C/100 m. See Figure 2 to identify the peripheral stations.
-------
20 10
J + S
S ',
10
•!+ s
Figure 59 Percentage of autumn 2315 GMT soundings with an elevated inversion base within 3000 m AGI_f and a thickness of 500 m
or less (left) or greater than 500 m (right) with a AT/AH of 0-0 47, 0 48-1 14, 1 15-2 82, 2 83-6 00, or > 6.0 °C/100 m (bottom to top)
Isopleths are for a thickness of 500 m or less and a AT/AH of 0 48-1 14 °C/100 rn See Figure 2 to identify peripheral stations
-------
I
i- _ _.„ ft ,Y
IS I
I
i
Figure 60. Percentage of winter 2315 GMT soundings with no inversion below 3000 m AGL (left) and with a decreasing temperature with
height (-AT/AH) greater than 1.2°C/100m in the layers 1-100, 101-250,251-500, 501-750, 751-1000, or 1001-1500 m AGL (right, bot-
tom to top). See Figure 2 to identify the peripheral stations.
90
-------
7.+ 1
«+ 'l
!+ i
•-/
Figure 61 Percentage of spring 2315 GMT soundings with no inversion below 3000 m (left) and with a decreasing temperature with height
(-AT/AH) greater than 1 2°C/100m in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, or 1001-1500 m AGL (right, bottom to
top) See Figure 2 to identify the peripheral stations
-------
. i 4
"A--4- «
''<" I i
t " M
•*J
»J
•jl-f ,}
! it
R* {
M+ '.
r -«-»
,!
tv.
! 8
™+ •,
V m
55,'
/ 2
BO-t ',
«+ ',
2!
Figure 62 Percentage of summer 2315 GMT soundings with no inversion below 3000 m (left) and with a decreasing temperature with height
(-AT/AH) greater than 1.2 °C/100m in the layers 1-100, 101-250, 251-500,501-750, 751-1000, or 1001-1500 m AGL (right, bottom to top).
See Figure 2 to identify the peripheral stations.
92
-------
• * s
»+ S
>•+ §
Figure 63, Percentage of autumn 2315 GMT soundings with no inversion below 3000 m (left) and with a decreasing temperature with height
(-AT/AH) greater than 1 2 "C/100 m in the layers 1-100, 101-250, 251-500, 501 750, 751-1000, or 1001-1500 rn AGL fright, bottom to top)
See Figure 2 to identify peripheral stations
93
-------
_ c .
K
+S
jt
" 1
"
-I
is
«+l «*
-
^
44
8
;
»
"
••
Figure 64. Percentage of summer 2315 GMT soundings with no inversion below 3000 m (left) and with a temperature decrease with height
(-AT/AH) greater than 0.8 "C/100 m in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, or 1001-1500 m AGL (right, bottom to top).
See Figure 2 to identify peripheral stations.
-------
LI g
J2 0
,1
14
15*
33 . .
.'1*
14 J"'y-'
if*n
i ''
i* s
L* D
L« 2
Figure 65 Percentage of winter 2315 GMT soundings with an elevated inversion base in the layer 1-100, 101-250, 251-500, 501-750, 751-1000,
1001-2000, or 2001-3000 m AGL (left, bottom to top), and a temperature decrease with height (-AT/AH) greater than 1 2 "C/100 m in the layer
below (right, bottom to top) See Figure 2 to identify the peripheral stations
95
-------
a
H
'H 5
s+:
; > 5
.
5
" •
5
1 *
0
0
0
0
1 D __
n
• • ,? 5
" ®!
P.J
!!
i
,,
B t
r :
i o
so
30
»+l
« I
tl 17
It
-
Figure 66. Percentage of spring 2315 GMT soundings with an elevated inversion base in the layer 1-100, 101-250, 251-500, 501-750, 751-1000,
1001-2000, or 2001-3000 m AGL (left, bottom to top) and a temperature decrease with height (-&T/AH) greater than 1.2 °C/100 m in the layer
below (right, bottom to top) See Figure 2 to identify the peripheral stations
96
-------
10 + 4
» °!
i a
it~ o
if i
1
v:
i* !
1.3 0 12 0
1* • IB 0
4 a 4 •
2 + • o S+D 4-0 LO + a
11 81 13 Z3 4
a a LO B 2 1 7 ZG ii
D Q G * 19 6 S
1!
i a
3 i
ii a
Figure 67 Percentage of summer 2315 GMT soundings with an eievated inversion base in the range 1-100, 101-250, 251-500, 501-750, 751-1000,
1001-2000, or 2001-3000 m AGL (left, bottom to top) and a temperature decrease with height (-AT/AH) greater than 1 2 "C/100 m in the layer
below (right, bottom to topi See Figure 2 to identify the peripheral stations
-------
0
1 ° fti" "~ ~ ~ ' ^ "
V lf ;y ', M^ '
-'""'I " 8 " ?V 1 -' ''' ' ? ,! i V"'
*+ o ; , •} ~ ,/ i 'i i"
s s ! • ' -- •'•+!• '« S J s rt
3 • LA_ /____ r 5+o j^ a 3 0 ' 9 1
3+ • I ----•.,,, , , jo,. A-"i ! i+ S --••»«
i ", '\ • ; 001! } J
-,- J ' ' i ,{ ! AS • v. .-"— "° "' ° ° • * i, 8
!i \.i l\ ;:.\ o iin ri.rM^;r? ll
* : ; 't 8 ' • i 't . f- - !* ', .' "4^ '
i ! 8* : < •" " '• -I •' ^f
_,'___ 1 J_ ., \ |B Q , ^ g !•-• g
i i'i •! • !TT> iJ '-' Vi"-'^" n ""1*! -i
T: : !+= ' ^ L, is : i* •••• --'--*- t t •' .*i
. . , . . , -JM--' / :,; „ ; .- |*i 1 1^
*j « i a ; u s |+ S *!ri~"'j+ • «+ s ' ' j-*"'
.' * 8 1 -J^+'« •* " II Is! •' '''**'. '* ' ! >• •
t J " * "1 * ' * I! * I ''.*'. * '_i il ;' i
1 ' HI "L i '^•/^'j>s~""**- '',"- "**"'•
2 "• 4,— ' | J >j" j i
\ / * * f? 8 \
\ «\ ! "J8 1?' 1
Tl ^\
50GO | D Z 0 110
o 27 a ti o 10 D 10 a
BIO 7010 10
f+B B+0 13-t-Q 19+0 140
« . S a 701203 00
51 Z • 12 3 14 4 • 0
1 • • 2211 90
Figure 68. Percentage of autumn 2315 GMT soundings with an elevated inversion base in the range 1-100, 101-250, 251-500, 501-750,
751-1000, 1001-2000, or 2001-3000m AGL (left, bottom to top) and a temperature decrease with height (-AT/AH) greater than 1.2 "C/100
m in the layer below (right, bottom to top). See Figure 2 to identify the peripheral stations.
98
-------
10 » 30
Figure 69. Percentage of winter 1115 GMT soundings with a surface-based inversion and an average relative humidity in the inversion
(bottomland in the 300-m layer above the inversion top (top) of >69% (left) and >89% (right). Isopleths are for surface-based inversions in
which the average relative humidity is >69% See Figure 2 to identify the peripheral stations
99
-------
Figure 70. Percentage of spring 1115 GMT soundings with a surface-based inversion and an average relative humidity in the inversion
(bottom) and in the 300-m layer above the inversion top (top) of >69% (left) and >89% (right). Isopleths are for surface-based inversions
in which the average relative humidity is >69%. See Figure 2 to identify the peripheral stations.
100
-------
Figure 71 Percentage of summer 1115 GMT soundings with a surface-based inversion and an average relative humidity in the inversion
(bottom) and in the 300-m layer above the inversion top (top) of >69% (left) and >89% (right) Isopleths are for surface-based inversions
in which the average relative humidity is >69%. See Figure 2 to identify the peripheral stations
101
-------
, L , ! /«+ 4
Figure 72. Percentage of autumn 1115 GMT soundings with a surface-based inversion and an average relative humidity in the inversion
(bottom) and in the 300-m layer above the inversion top (top) of >69% (left) and >89% (right). Isopleths are for surface-based inversions
in which the average relative humidity is >69%. See Figure 2 to identify the peripheral stations.
102
-------
',* 8
Figure 73 Percentage of all 2315 GMT soundings with a surface-based inversion and an average relative humidity in the inversion
'bottom/ and in the 300-m layer above the inversion top (top) of >69% (left) and >89% (right). Isopleths are for surface-based inversions
in which the average relative humidity is >69%. See Figure 2 to identify the peripheral stations
103
-------
Figure 74. Percentage of winter 1115 GMT soundings with an elevated inversion based within 3000 m AGL and an average relative
humidity m the entire layer below the inversion base (bottom) and in the inversion (top) of >69% (left) and >89% (right). Isopleths are for
elevated inversions below which the average relative humidity is >69%. See Figure 2 to identify the peripheral stations.
-------
Ho. «
n* i
Figure 75 Percentage of spring 1115 GMT soundings with an elevated inversion base within 3000 m AG L and an average relative humidity
in the entire layer below the inversion base (bottom) and in the inversion (top) of >69% (left) and >89% (right) Isopleths are for elevated
inversions below which the average relative humidity is >69% See Figure 2 to identify the peripheral stations
105
-------
50
j y---—A .- r C -
" • J
2* + 13
30 + II
a* a
Figure 76. Percentage of summer 1115 GMT soundings with an elevated inversion base within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in the inversion (top) of >69% (left) and >89% (right). Isopleths are for elevated
inversions below which the average relative humidity is >69%. See Figure 1 to identify the peripheral stations.
106
-------
20
Figure 77 Percentage of autumn 1115 GJV1T soundings with an elevated inversion base within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in the inversion (top) of >69°o (left) and >89% (right). Isopleths are for elevated
inversions below which the average relative humidity is p-69%. See Figure 2 to identify the peripheral stations
107
-------
it* I
20
50
Figure 78. Percentage of winter 2315 GMT soundings with an elevated inversion base within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and in the inversion (top) of >69% (left) and >89% (right). Isopleths are for elevated
inversions below which the average relative humidity is >69%. See Figure 2 to identify the peripheral stations.
108
-------
Figure 79 Percentage of spring 2315 GMT soundings with an elevated inversion base within 3000 m AG L and an average relative humidity
in the entire layer below the inversion base (bottom) and in the inversion (top) of >69% (left) and >89% (right) Isopleths are for elevated
inversions below which the average relative humidity is ^69% See Figure 2 to identify the peripheral stations.
109
-------
SO 30 20
10
•if*&L
iT-Ki__
-^ ^--r^^-A
# ;^
mj-'j r
C" >"
-~T7, 1
-;^K-
.^,
' -a ID
Figure 80. Percentage of summer 2315 GMT soundings with an elevated inversion base within 3000 m AGL and an average relative humidity
in the entire layer below the inversion base (bottom) and m the inversion (top) of >69% (left) and >89% (right). Isopleths are for elevated
inversions below which the average relative humidity is >69%. See Figure 2 to identify the peripheral stations.
110
-------
30 10
-------
Figure 82 Percentage of winter 1115 GMT soundings with no inversion below 3000 m AGL and an average relative humidity >69% (left)
and>89% (right) in the layers 1 -100, 101-250, 251-500, 501-750, 751-1000, and 1001-1500 m AGL (bottom to top). Isoplethsare for an
average relative humidity >69% in the layer 251-500 m AGL. See Figure 2 to identify the peripheral stations.
112
-------
10
Figure 83 Percentage of spring 1115 GMT soundings with no inversion below 3000 m AGL and an average relative humidity >69% (left)
and >89% (right) in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, and 1001-1500 m AGL (bottom to top) Isopleths are for an
average relative humidity >69% in the layer 251-500 m AGL, See Figure 2 to identify the peripheral stations.
113
-------
ii*
IS
30 23
38 .. 24
30* J4
30 28
JO 21
. s
Figure 84. Percentage of summer 1115 GMT soundings with no inversion below 3000 m AGL and an average relative humidity >69% (left)
and >89% (right) in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, and 1001-1500 m AGL (bottom to top). Isopleths are for an
average relative humidity >69% in the layer 251-500 m AGL. See Figure 2 to identify the peripheral stations
114
-------
Figure 85 Percentage of autumn 1115 GMT soundings with no inversion below 3000 m AGLand an average relative humidity >69% (left)
and >89% (right) in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, and 1001-1500 m AGL (bottom to top) Isopleths are for an
average relative humidity >69% in the layer 251-500 m AGL. See Figure 2 to identify the peripheral stations
115
-------
M;
I I*
H
£ i
,
4i'14 }
It'
4:
""*»•« :
u
If
10
41
40
»4 1
8*1
1! I
: : 8 11 : s
+ ? :+ § 5* i !* S
t 10 92 nO
1 10 33 • 0
• Z
* } 1
• 2
+ j
Figure 86. Percentage of winter 2315 GMT soundings with no inversion below 3000 m AGLand an average relative humidity >69% (left)
and>89% (right) in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, and 1001-1500m AGL (bottom to top). Isopleths are for an
average relative humidity >69% m the layer 251-500 m AGL. See Figure 2 to identify peripheral stations.
116
-------
3D
is* I
?! I
Figure 87 Percentage of spring 2315 GMT soundings with no inversion below 3000 m AGL and an average relative humidity >69% (leftl
and >89% (right) in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, and 1001-1500 m AGL (bottom to top) Isopleths are for an a
average relative humidity >69% in the layer 251-500 m AGL See Figure 2 to identify peripheral stations
117
-------
Figure 88. Percentage of summer 2315 GMT soundings with no inversion below 3000 m AGLand an average relative humidity >69% (left)
and>89% (right) in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, and 1001-1500 m AGL (bottom to top) Isopleths are for an
average relative humidity >69% m the layer 251-500 m AGL. See Figure 2 to identify peripheral stations.
118
-------
20
I
Figure 89 Percentage of autumn 231B GMT soundings with no inversion below 3000 m AGL and an average relative humidity > 69% (left)
and >89% (right) in the layers 1-100, 101-250, 251-500, 501-750, 751-1000, and 1001-1500 m AGL (bottom to top) Isopleths are for an
average relative humidity >69% in the layer 251-500 m AGL See Figure 2 to identify the peripheral stations.
119
-------
I 29
!$*',
32 -f 21
21 i 1
2 JO
11 22'
E*!?
i S 3
___[ .
28 + 10
* 9
J •
3 21
40 + 34
ia 21
24 «
22 2!
S+II
• 1
• "' ^
^i
1 3
s;.^
j+s
? s
S*8
10 3
E 21
34+ n
41 24
* 15
& II
24 + II
'I !
2 14
1 21
33+20
? 5
8*1
1 D
0 JQ
1 18
18+9
A I
Uii
a ' i « 20
D \ JL - 3C+ 11
>' U 3
- V, " D
JS 01*
H+I r!f .
• 0. . I r
to* !
! -ft
V 'I
A 53
It + U
? Ji :.
? s
« + is
is i
5 H-
i
ji+1 JCij- '^H ;' ,!+g-. "' ^'S.i**
9 IB
2 Zf
34 -f 11
\ '1 5
v
-A. J 4
W» 13
*« c '3s
W' - ' '.•
^
8' n
11
*, 0 4
\ 1 33
~
20 I
20+ :
»+.!
Figure 90. Percentage of winter 1115 GMT soundings with an inversion base at the surface and wind speeds at the
surface deft] and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0, and >10.0 m/s (bottom to top) See Figure 2 to
identify peripheral stations.
120
-------
0 14
1 H
II t 1
4
I 2J
H t 11
Id 22
47 +«
ID + 19
29 ::
,1 'A
as+ is
10 0 m/s (bottom to top) See Figure 2 to
identify peripheral stations
121
-------
1"
•&B-
Oi Z1
11'. 90
2 36
40 + 21
ii za
41 + 10
1 1
i__JL
1 48
20 21
474 B
Bl + 21
II i
0 0
z av
8*4 n
!s i.»
Aril
1 24
14 + 13
^j-2 ^
0 II
• . »l
+ '{
<*
12 I
." r!
214 ai
« ,f,
X"
.;IS
10
T'S
a i
1 IB
Figure 92. Percentage of summer 1115 GMT soundings with an inversion base at the surface and wind speeds at the
surface (left) and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0, and>10.0m/s (bottom to top). See Figure 2 to
identify peripheral stations.
122
-------
J: 29
4 14
1 10
10 13
U+ 6
» 19
40 •+• 21,
s a
41 -ti5B
IT'S
Figure 93 Percentage of autumn 1115 GMT soundings with an inversion base at the surface and wind speeds at the
surface (left) and at 300 m AGL (right) in the ranges calm, 01-25, 2.6-5 0, 5 1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify peripheral stations.
123
-------
•Ml
i .s
t _a _ -,,
! ii
1* f
1 JL.-JL
3 16
•v i:
0 G
'1* ;
9 * 2
G 3
3 D
! vl
23+ 14,
W'
i-*S -
23 + 12
2 13
IB + 10
1 2 -
'» $
38 -tv TE
^ J
0 ; 3
V- 2P
'7ff+ J4
S^ ? \
'$> I \
,>-•
D 2
A+8
5? SI
Figure 94. Percentage of winter 2315 GMT soundings with an inversion base at the surface and wind speeds at the
surface (left) and at 300m AGL (right) in the ranges calm, 0,1-2.5, 2.6-5.0, 5.1-10.0, and>10.0 m/s (bottom to top). See Figure 2 to
identify peripheral stations.
124
-------
r
V i \
•?? 1 \
L
•
-V "o
Figure 95 Percentage of spring 2315 GMT soundings with an inversion base at the surface and wind speeds at the
surface (left) and at 300 m AGL (right) in the ranges calm, 0 1-2 5, 2.6-5 0, 5.1-10 0, and >10.0 m/s (bottom totop) See Figure 2 to
identify peripheral stations.
125
-------
\n o
i
VTT
0 '0
j.
>•'+ I
S 3
Figure 96. Percentage of summer 2315 GMT soundings with an inversion base at the surface and wind speeds at
the surface (left) and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2
to identify the peripheral stations.
126
-------
I> I
Figure 97 Percentage of autumn 2315 GMT soundings with an inversion base at the surface and wind speeds at the
surface (left) and at 300 m AGL (right) in the ranges calm, 0 1-2.5, 2 6-5.0, 5 1-10.0, and >10.0 m/s (bottom to top} See Figure 2 to
identify the peripheral stations
127
-------
rx1j
k(
j *•> 10
r •
ri v
'8*1
!
,
..
1+ i
I + 2
LA.
it!*
fTT"~ « «
i 4 .J '! i n jl
i+i : :+ i M*.'
i ! • 1 ' '
i i
'5+ '! ^
' '
\
J II
19 11
' '
»*
12
• •
G 24
IB 14
1C + G
11 fl
1+1
92
10
93
8+2
11
it
4 12
19+11
E 3
19
fl+ 1
a n
14 1C
S3
an
Figure 98. Percentage of winter 1115 GMT soundings with an elevated inversion base between 1 -3000 m AGL and wind speeds at the
surface (left) and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
128
-------
6 S
1 I 40
'5T4-" 9
Figure 99. Percentage of spring 1115 GMT soundings with an elevated inversion base between 1-3000 m AGL and wind speeds at
surface (left) and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2 6-5.0, 5.1-10 0, and >10.0m/s (bottom to top) See Figure 2 to
identify the peripheral stations
129
-------
V •
. .
* >
It 16
V '!
1 ---------------------
11 + 10
I 4
3 •
14 +
! .i10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
130
-------
n + IB
!0 !B
?* !
Figure 101 Percentage of autumn 1115 GMT soundings with an elevated inversion base between 1 -3000 m AGL and wind speeds at
the surface (leftl and at 300 m AGL (right) in the ranges calm, 0 1-2 5, 2 6-5 0, 5.1-10 0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
131
-------
1 ID
Vl
a o
« ifl
21 n
18 -t- 4
lit
«
14 U
i»+ ia
u SB
20 12
12 + G
Sn
12
Figure 102. Percentage of winter 2315 GMT soundings with an elevated inversion base between 1-3000 m AGL and wind speeds at
the surface (left) and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0, and >10.0 m/s (bottom to top) See Figure 2 to
identify the peripheral stations.
132
-------
~~T" '
. ',. W
Z2 It * 1
23 + •— -
4 2
•> r. l
-H.3 S2
"a* ls
rt •*• •
f »
c o
, -
30 + H.
W <*• is
**-" '!,-
a v-
\t
V
\
\
i is
1+23
U ii
« + 16
Figure 103 Percentage of spring 2315 GMT soundings with an elevated inversion base between 1 -3000 m AGL and wind speeds at
the surface (left) and at 300 m AGL (right) in the ranges calm, 0 1-2.5, 2 6-5.0, 5.1-10 0, and >10.0 m/s (bottom to top). See Figure 2
to identify the peripheral stations
133
-------
l-i
•
f\ .
• 1
0 B
!+ !
1 1
• 1
0
i j 2 l
L + 1 80
i a
: i
X+ i
o a
, ,
>M K
. , .^
{!+1!
• a
•i-^y
ID n
fi+'l ^*'i
•!•!
2! iS
32+ 18
i* i
J 0
Figure 104. Percentage of summer 2315 GMT soundings with an elevated inversion base between 1-3000m AGLand wind speeds at
the surface (left) and at 300 m AGL (right) in the ranges calm, 0,1-2.5, 2.6-5.0, 5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
134
-------
•L 4
B 10
12+ •
6 I
! V
v i
4*1
1 31
IB Z4
36 + 12
58 14
6+12
*
^ a — 4 _
,L4
11 29
49+ 20
•$,'?,
I i
w
\
Figure 105 Percentage of autumn 2315 GMT soundings with an elevated inversion base between 1-3000 m AGL and wind speeds at
the surface (left) and at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5 1-10 0, and >10.0 m/s (bottom to top). See Figure 2 to
identify the peripheral stations.
135
-------
!* 8
2, !
,3 i!
•r s
i-j
Figure 106. Percentage of all 1115 GMT soundings with no inversion below 3000 m AGL and wind speeds at the surface (left) and at
300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to identify the peripheral
stations.
136
-------
A ,j
fS+1?
•r i
S+ !
•r i
Figure 107 Percentage of winter 2315 GMT soundings with no inversion below 3000 m AG L and wind speeds at the surface (left) and at
at 300 m AGL (right) in the ranges calm, 0 1-2.5, 2 6-5 0, 5 1-10 0, and >10 0 m/'s (bottom to top) See Figure 2 to identify the peripheral
Qtatmnc
stations
137
-------
io it I
'! II 3&
'It-'i-vl,
•vl«
V- T «
u
i-r
/ • >
ii+S
A ,i
,44,4
1 »
<.|
«: g
M+ 14
iHl
B a
^+?
^ ij
55+ M
H !>!
i ii
« if
144 rf
'.= !|
Tl
*J
Li
.«1^! L-jyr-J?t?i
-—^J_r ^^ : j
•r i
-
1 4
r!
U 5
S 8
I
Figure 108 Percentage of spring 2315 GMT soundings with no inversion below 3000 m AGL and wind speeds at the surface (left) and
at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5 1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to identify the peripheral
stations
138
-------
48 + 34
1.0 tO
,1 ,!
il + 41
JS.
Figure 109 Percentage of summer 2315 GMT soundings with no inversion below 3000 m AGL and wind speeds at the surface (left) and
at 300 m AGL (right) in the ranges calm, 0 1-2.5, 2.6-5.0, 5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to identify peripheral
stations
139
-------
tL:i
n»,
f 1
HI
* i
HI
• •
ij
8
•
-. 8
!
,••
M
•
,fl
,! J
H '•'
y*4
*! 9
li,,^
8
1«
1
•
tt
;}
5 »U-
»• «
•
g
i t
r'i
• 8
~^-V^ ~^
/ '}
i"i\
/__
• i >
V ' /
IJ_Y
-, i
.'* S
Figure 110. Percentage of autumn 2315 GMT soundings with no inversion below 3000 m AGLand wind speeds at the surface (left) and
at 300 m AGL (right) in the ranges calm, 0.1-2.5, 2.6-5.0, 5.1-10.0, and >10.0 m/s (bottom to top). See Figure 2 to identify the peripheral
stations.
140
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TECHNICAL REPORT DATA
1 S ACCESSIOF>NO
CLIMATOLOGICAL SUMMARIES OF THE LOWER FEW KILOMETERS
OF RAWINSONDE OBSERVATIONS
fc PfcRFORMtNG ORGANIZATION CODE
A U1 H O R t S'
George C. Holzworth and Richard W. Fisher
RL°OFn DATE
May 1979
8 PERFORMING ORGANIZATION REPORT NO
9 F'LFU ORMING ORGANIZATION NAME AND ADDRESS
I PROGRAM LLtzMENT NO
(Same as Box 12)
12 SPONSORING AGENO NAME AND ADDRESS
Environmental Sciences Research Laboratory - RTP, NC
Office of Research and Development
U.S Environmental Protection Agency
Research Triangle Park. NC 27711
1AA603
1 CONTRACT/GRANT NO
13 TYPE OF REPORT AND PERIOD COVERED
Inhouse 3/74-3/79
I4 SPONSORING AGENCY CODE
EPA/600/9
15 SUPPLEMENTARY NOTES
Summaries of atmospheric structure, based on rawinsonde measurements taken
twice daily at 76 United States Weather Service stations, are presented on national
maps. The data include frequencies of surface-based and elevated inversions,
inversion thicknesses, and elevated inversion base-heights. Frequencies of high
relative humidity are given for inversions and adjacent layers. Frequencies of
wind speed categories at the surface and 300 m above are presented for surface-
based, elevated, and no-inversion cases. Finally, lapse rates are characterized
within and below inversions, and in specified layers through 1500 m for soundings
with no inversion. Representative data are isoplethed for illustrative purposes,
but many figures are without isopleths because no single variable is generally
representative. Some general conclusions are: 1) inversions are virtually always
present at most locations; 2) inversions are almost always greater than 100 m
thick, sometimes more than 1000 m; 3) shallow inversions tend to be more intense
(large AT/AHJ than thick inversions; 4) wind speeds with surface-based inversions
are generally slower at the surface than at 300 m and the most common surface
speed-class is 2.6-5.0 m/sec. The data presented in this report should be of
considerable interest to those concerned with the atmospheric boundary layer.
KEY WORDS AND DOCUMENT ANALVStS
DESCRIPTORS
b IDENTIFIERS-OPEN ENDED TERMS
* Climatology
* Meteorological charts
* Wind veloci ty
* Temperature inversions
* Humidity
Boundary layer
Rawinsonde measurements
COSATI Tield/Grt
04B
08B
20D
RELEASE TO PUBLIC
SECL'RITV CLASS 'ThltR
UNCLASSIFIED
21 NO OF PAGES
151
UNCLASSIFIED
111
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US ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Deveiopmen'
Environmental Research Information Center
Cincinnati, Ohio 45268
OPFIC IAL BUSINESS
PPNALTYF-ORPRiVAieUSe S3OC
AN tQUAL OPPORTUNITY LMFLOVLR
PO-STAGf, AND F££S PAID
U S ENVIRONMENTAL PROTECTION AGENCY
EPA-335
Publication No. EPA-600/4-79-026
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