Meteorology and Air Quality Patterns In St Louis Raps Program-upper Level Analyses

&ERA
United States
Environmental Protection
Agency
Environmental Sciences Research
Laboratory
Research Triangle Park NC 2771
Research and Development
EPA-600/S3-82-056 July 1982
Project Summary
Meteorology and Air Quality
Patterns in St. Louis RAPS
Program—UppiH
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pattern types were determined they
were correlated with ozone (Oa) carbon
monoxide (CO), total suspended parti-
cles (TSP), sulfate (SOi), and nitrate
(NO 3) concentrations from the St. Louis
Regional Air Pollution Study (RAPS)
program to obtain relationships between
weather types and air quality.
Surface and upper air weather data
from National Weather Service stations
in a region (800-km radius) centered on
St. Louis were used in the weather
typing program. Seasonal weather types
were identified, and a high percentage
generally approaching 90% of the daily
weather patterns were successfully
typed.

Research Methods
To describe the desired wind flow
through the St. Louis region, research-
ers found it necessary to identify by map
types the upper level wind conditions as
well as the surface flow. For practicabil-
ity and ease of data gathering, the 850-
mb pressure pattern (which is at a
height of approximately 1.5 km above
sea level) was used to represent wind
flow at the upper level. Another class of
wind patterns, based on the surface
geostrophic wind, was also used to
characterize the flow patterns across
this region. The geostrophic wind was
used because it takes into account the
pressure field at the surface and is a
reasonable approximation of the ob-
served wind at a height of approximately
1000 m. The surface pressure patterns
across this region had been determined
previously by Robinson and Boyle in
their study of synoptic weather patterns
around St. Louis. Thus, the weather
situations across the St. Louis region
could be identified on the basis of three
different types of patterns—the 850-mb
pressure, the geostrophic wind based
on surface pressure differences, and
the surface pressure. The weather data
covered the four-year period 1973 to
1976.
Lund's statistical correlation proce-
dure for map type was used with 850-
mb geopotential heights to approximate
upper level flow patterns and with
surface pressure differences between
fixed pairs of stations to approximate
the geostrophic wind field. Lund's tech-
nique is basically a simple linear corre-
lation between values of a weather
parameter (e.g., 850-mb height) at a
given set of stations on one day and
values at the same stations on a second
day. Computer analysis permits each
day's weather pattern to be correlated
with every other day considered in the
program. It is then assumed that a good
correlation between values on two
separate days is an indication of similar
weather patterns on the two tested
days. In this study a correlation coeffi-
cient of 0.70 or greater was used with
850-mb data to relate weather patterns,
and a coefficient of 0.65 or greater was
used for the geostrophic wind patterns.
During this correlation process a num-
ber of key maps are identified, and these
maps become base maps for the various
flow patterns. Table 1 summarizes the
seasonal map types by base map data
for the 850-mb patterns, and Table 2
summarizes the geostrophic wind pat-
tern base maps. The number of cases of
occurrence for each map type is also
listed.
To complete the objectives of this
study, pollutant data from the St. Louis
Regional Air Measurements (RAM) net-
work of the RAPS program were corre-
lated with the synoptic map types. From
the pollutant data collected by the
network, five pollutants were chosen:
02, CO, TSP, SOl
In the RAPS program, air quality data
were collected from January 1975
through December 1976. Sampling for
Oa and CO was continuous and was
averaged on an hourly basis at all of the
25 RAM stations. High volume sampling
was used for TSP, SOY and NOa, and
24-h average samples were collected
every third day at selected stations
throughout the network.
Stations representative of the air
quality of the St. Louis central urban
area were chosen from the 25 stations
in the network. For O3, and CO, stations
101, 104,105,106, 107, and 110 were
selected, and for TSP, SOY and NOa,
stations 103, 105, 106, and 108 were
chosen. These stations were selected to
provide an indication of the average
concentrations of the pollutants across
the central part of the St. Louis com-
mercial and industrial areas. Research-
ers expected that changes in synoptic
conditions would have the most influ-
ence and thus be detected most readily
in this part of the city because of the
high concentrations there.
The pollutant data were collected,
classified and averaged by synoptic map
types for each season for both the 850-
mb and geostrophic map types. The Oa
data were averaged by daily one-hour
maximum concentrations. The CO data
were analyzed by daily average concen-
trations for the two-year period. The
data for TSP, SOY and NOa were
analyzed by 24-h averages for every
third day for the two-year period because
that was the frequency of sample col-
lection.
To determine if a significant relation-
ship between map types within a season
occurred, statistical tests were applied
to the stratified pollutant data. Since
researchers found that the pollutant
data used in this study usually followed
a log-normal distribution, the logarithms
of the pollutant values as well as the
basic pollutant data were used for the
tests. The statistical tests were then
applied to both the arithmetic and
geometric means of the concentration
data within each map type. The statis-
tical tests included an initial analysis of
variance, and then a more powerful
statistical procedure, the Duncan's New
Multiple Range test, was employed
(Steel and Torrie)ft- This test compared
means for pairs of map types within a
season and determined if significant
differences existed between the map
types. The test then ranked the map
types from higher to lower concentra-
tion. Finally, the test indicated which
types were significantly different from
each other and which were not. Both
the actual concentration data and the
logarithms of the concentration data
were used.
Table 3 presents the results of the
statistical analysis of the 850-mb pat-
terns and the average daily maximum
St. Louis RAPS Oa concentration. These
data illustrate the results obtained in
the program. On a seasonal basis, Oa
concentrations were related to the 850-
mb weather types in spring, summer,
and fall, but not in winter. This relation-
ship is not unexpected considering the
general absence of pollutant Oa in the
winter. The column headed "Sig." or
significance indicates the types, by rank
order, that differ from the identified
type. For example, in spring, weather
map Type E or the Rank 1 type is
significantly different in average Oa
concentration from the types ranked 2
through 6, i.e., all of the other spring
map types. Similar statistical results
were developed for the other pollutants
and for the geostrophic wind patterns.
tfSteel, R. G D., and J. H. Tome. Principles and
Procedures of Statistics. McGraw-Hill Book Com-
pany, Inc., New York, NY, 1960. 481 pp.
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Table 1 . Summary of Synoptic Map Types for 850-mb Level. 1973-1976
Winter Spring Summer
I850W) (850SP) (850S)
Date of
Type Base Map
A Feb. 13. 1974
B Jan. 8, 1976
C Feb. 1. 1973
D
E
F
Misc
Total Types
Total Cases
Percent Typed
No. of
Cases Date of
(r >O. 70) Base Map
199 March 6, 1975
80 May 1. 1973
41 April 11, 1973
March 13, 1974
April 28, 1976
April 25, 1976
25
320
345
92.8
No. of
Cases Date of
Fall
(850F)
No. of
Cases Date of
(r>0.70) Base Map (r>O.70) Base Map
105 June 4. 1975
89 July 30. 1974
82 July 8. 1974
15 June 27. 1974
10 June 6. 1976
11 June 19, 1976
36
312
348
89.7
125 Nov. 13, 1973
65 Sept. 30. 1974
69 Sept. 13, 1976
14 Nov. 28. 1973
14 Sept. 26, 1975
24 Oct. 21, 1974
42
311
353
88.1

No. of
Cases
(r>0.70)
81
70
52
10
12
9
23
234
257
91.0
Table 2. Summary of Seasonal Synoptic Map Types for Geostrophic Wind, 1973-1976
Winter
(GeoW)

Date of
Type Base Map
A Jan. 17, 1973
B Dec. 17, 1975
C Jan. 29, 1973
D Feb. 7, 1976
E Feb. 19, 1974
F Dec. 14, 1975
G Dec. 18. 1973
H Dec. 23, 1975
1 Jan. 25. 1976
Misc.
Total Typed
Total Cases
Percent Typed
Spring
IGeoSP)
No. of
Cases Date of
(r >O.65) Base Map
68 May 6, 1973
57 March 7, 1975
30 April 4, 1975
21 March 18, 1976
22 March 12. 1976
18 April 7, 1974
24 May 12, 1975
13 March 7, 1973
19 May 27, 1973
89
272
361
75.4
Summer
(GeoS)
No. of
Cases Date of
(r>O.65) Base Map (r
74 July 16, 1975
37 July3, 1974
41 July 11, 1974
33 July 4, 1976
20 Aug. 8, 1974
21 July 27, 1973
17 July 24. 1975
12 July 8. 1973
10 Aug. 14, 1976
103
265
368
72
Fall
(GeoF)
No. of
Cases Date of
>0.65) Base Map
78 Oct. 29, 1974
41 Sept. 9. 1976
37 Oct. 2. 1974
21 Oct. 2, 1975
25 Sept. 24, 1974
22 Nov. 9, 1976
18 Sept. 15, 1976
16 Nov. 23, 1974
13 Nov. 23. 1973
96
271
367
73.9

No. of
Cases
(r>0.65)
90
60
33
24
19
16
14
14
17
76
287
363
79.1
Conclusions
The statistical map classification pro-
cedure developed by Lund served as
the basis for compiling comprehensive
sets of primary seasonal weather map
types for the 850-mb level and geo-
strophic wind, based on surface pres-
sure difference for the four-year period
1973 to 1976 for the St. Louis region.
These map types were matched with
mean concentrations of Oa, CO, TSP,
SOV and NOs data applicable to the St.
Louis central urban area using obser-
vations from the St. Louis RAPS pro-
gram for the periods 1975 and 1976.
The average pollutant data stratified
by weather type were submitted to an
analysis of variance statistical evalua-
tion using the Duncan's Multiple Range
test to determine significant differences
between map types within each season
of the year (Steel and Torrie).tt The
results indicated that the synoptic scale
patterns for both the 850-mb surface
and the geostrophic winds are reflected
by the pollutant concentrations for all of
the pollutants considered. Higher pollu-
tant concentrations repeatedly occurred
with wind flows from the south or the
presence of a dominant high pressure
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Table 3. Seasonal 850-mb Map Types Ranged by Oa Concentrations'
Winter
Rank
1

5
6

Type /V"
B 170

C 94

A 317

Cone.0
22

Sig."
None

None

Remarks
North flow, low
to ENE
SSW flow, low to
west
West flow, low to
NE

Type
E

C
F

N*
43

238

183

196
16

Spring
Conc.c
71

47
47

Summer
Rank
1

Type V
E 57

A 316

C 136

B 140

D 40

F 39

Conc.c
88

Sig.a
3-6

3-6

1,2,4-6

1-3,6

1-5

Remarks
East flow, high to
NNE
WSW flow, high to
south
SSW flow, high to
east
NWflow, low to
NE
SW flow, low wind
speeds
NNW flow, low to
NE
Type
F

/V"
27

226

149

193

Cone.0
75

Siga
2-6

1.5

1.2
1

Fall
Sig<
2-6

1,5,6

1.5,6

1-4,6

1-5

Remarks
Calm wind, high to
NE dominates
NE flow, low to E,
high to NW
WSW flow, low to
NW, high to SE
SW flow, low to W,
high to SE
NW flow, low to NE
Center of low
pressure

Remarks
Calm winds, center
of high
SW flow, high to
south
SW flow, high to
east
NE flow, low to NE.
low winds
NW flow, high to
west
Center of low
pressure
^Averaged for stations 101. 104. 105. 1O6. 1O7. and 110.
"N = number of station observations.
cConc. = concentration in ppb.
"Sig. = indicates a significant difference between the ranked types listed and the ranked type of concern.
system in the area while lower concen-
trations occurred with the presence of a
low pressure system or strong wind
fields. Maximum mean pollutant con-
centrations differed by season, depend-
ing on the type of pollutant. For example,
higher 03 concentrations occur during
the summer months due to more favor-
able conditions for the photochemical
reaction processes. Low Oa concentra-
tions occur during the winter season.
The 850-mb and the geostrophic map
types were compared to the surface
map types developed by Robinson and
Boyle.t The conclusion was that the
850-mb map type was the most effective
of the three systems in stratifying the
pollutant data. The 850-mb map type
had a lower number of map types per
season than the other two systems, and
thus a better resolution of major patterns
was obtained for the 850-mb level than
for the surface or geostrophic map
types.
The results of this investigation should
provide a basis for further studies
relating airquality to synoptic flow. This
study provides a basis for the use of
850-mb flow level map types with
diffusion models for the prediction of
pollutant concentrations at receptors
located a long distance from a major
source. The results could also aid in
predicting periods of high or low pollu-
tant concentrations in an effort to curtail
harmful pollutant episodes.
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M. Vuono, F. Shives, and E. Robinson are with Washington State University,
Pullman, WA 99164.
George C. Holzworth is the EPA Project Officer (see below).
The complete report, entitled "Meteorology and Air Quality Patterns in St. Louis
RAPS Program. Upper Level Analyses," (Order No. PB 82-217 522; Cost:
$13.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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