vvEPA
United States
Environmental Protection
Agency
Research and Development
PROJECT REPORT
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 27711
October 1987
DEVELOPMENTS IN NATIONAL WEATHER SERVICE
f'EIEOROLOGICAL DATA COLLECTION PROGR/V1S
AS RELATED TO EPA AIR POLLLTION MODELS
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DEVELOPMENTS IN NATIONAL WEATHER SERVICE METEOROLOGICAL
DATA COLLECTION PROGRAMS AS RELATED TO EPA AIR POLLUTION MODELS
by
Thomas E. Pierce and D. Bruce Turner
Meteorology and Assessment Division
Atmospheric Sciences Research Laboratory
Research Triangle Park, NC 27711
ATMOSPHERIC SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NC
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NOTICE
The information in this document has been funded by the United States
Environmental Protection Agency. It has been subject to the Agency's peer
and administrative review, and it has been approved for publication as an
EPA document. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
AFFILIATION
Mr. Thomas E. Pierce and Mr. D. Bruce Turner are on assignment from the
National Oceanic and Atmospheric Administration. Mr. Pierce is a Meteoro-
logist in the Environmental Operations Branch, Meteorology and Assessment
Division, Environmental Protection Agency, Research Triangle Park, NC.
Mr. Turner is Chief of the Environmental Operations Branch.
ii
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ABSTRACT
During the next decade, the National Weather Service (NWS) will be
upgrading its meteorological instrumentation and data dissemination proce-
dures. Because these changes will affect the operation of the U.S. Environ-
mental Protection Agency's (EPA) air pollution models, this project has
been undertaken to report on proposed changes and to recommend how to make
optimal use of the new NWS data products.
New instrumentation will include automated surface observation systems,
next generation radar, and remote profilers. Data dissemination is being
upgraded with an automated weather interactive processing system, the
conversion of data tapes to an element format, and the introduction of data
formats that are compatible with personal computers. Complete descriptions
of existing and new formats that are applicable to EPA air pollution models
are given in the Appendices.
To maximize the usefulness of NWS meteorological data, the following
actions are recommended: (1) adapt the EPA meteorological processors to
read the new data formats and upgrade them to incorporate advances in dif-
fusion meteorology; (2) encourage the collection of meteorological data
specific to diffusion modeling and investigate the feasibility of collecting
some of these data at NWS sites; (3) improve the handling and formatting of
NWS data for regional-scale models; and (4) maintain active communication
with the National Climatic Data Center.
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CONTENTS
Abstract iii
Figures vi
Tables vi
Acknowledgements vii
1. Introduction 1
2. Current Requirements 3
UNAMAP Models 3
Regional models 10
3. Proposed NWS Renovations 11
Instrumentation 11
Data Dissemination 17
4. Summary and Recommendations 21
References 23
Appendices
A. Description of the TD-1440 format 25
B. Description of the TD-3280 format 45
C. Description of the TD-5600 format 85
D. Description of the TD-6200 format 89
E. Description of the TD-9689 format 107
F. Description of the TD-9773 format Ill
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FIGURES
Number
1
2
Determination of twice-daily mixing heights
Determination of hourly mixing heights . . .
Page
7
8
TABLES
Number
Page
Meteorological requirements for UNAMAP . . .
(Version 6) models
Meteorological data formats used with UNAMAP
(Version 6) models
Variables used in the TD 1440 format ....
vi
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ACKNOWLEDGEMENTS
The authors would like to thank the many individuals within the National
Oceanic and Atmospheric Administration and the U.S. Environmental Protection
Agency who provided much of the information contained in this report. In
particular, the following people are recognized:
National Climatic Data Center (NCDC) -
Mr. Richard Heim (Climatological Services)
Mr. Alva Wallis (Climatological Services)
Mr. Richard Davis (Data Base Administration)
Mr. Robert Quayle (Data Operations)
Mr. Kenneth Davidson (Systems Integration and Planning)
National Weather Service (NWS) -
Ms. Mary Heffernan (AWIPS-90/NOAAPORT)
Mr. Paul Hexter (NEXRAD)
Dr. Joe Facundo (Upper-Air)
Dr. James Almazan (Office of the Federal Coordinator)
Mr. Jon Paerin (ASOS)
Mr. Steve Short (ASOS)
Mr. Newton Page (NOAANET)
Dr. Robert Strickler (Instrument Systems; Test and
Evaluation Division)
Environmental Protection Agency (EPA) -
Mr. William Keith (Office of the Federal Coordinator)
The authors would also like to thank Mrs. Sylvia Coltrane for her word
processing expertise and especially Mr. John Irwin for his encouragement
and review of this project.
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SECTION 1
INTRODUCTION
One of the principal inputs to an air pollution model is meteorological
data. Collecting and archiving the data poses a challenge to those involved
in diffusion modeling. The Nuclear Regulatory Commission (NRG) and the
Environmental Protection Agency (EPA) have addressed this problem of meteor-
ological data quite differently. The NRC requires that nuclear installa-
tions collect comprehensive meteorological data, including temperature
differences, hourly average winds, and turbulence fluctuations. These
measurements are usually taken on masts at heights ranging from 30 to 100 m.
In some localities, such as near a large body of water, multiple meteoro-
logical masts are required. In contrast, EPA regulates a greater number
and many more types of sources than the NRC. Because it is impractical for
every potential emitter of air pollution to operate a comprehensive on-site
meteorological monitoring program, EPA has traditionally relied on meteoro-
logical data collected by the National Weather Service (NWS). EPA's models
use simplistic characterizations of diffusion meteorology using only a few
measured NWS meteorological variables. For example, the rate of dispersion
is determined by a Pasquill stability class as estimated from routine obser-
vations of wind speed, cloud cover, and ceiling height. Hourly estimates
of plume rise, dilution, and transport direction are based on a single
2-minute average wind value reported by an observer on the hour.
During the past few years, the NWS has started to modernize its meteor-
ological instrumentation and data dissemination systems, and EPA has begun
efforts to use additional meteorological information to characterize dif-
fusion (EPA, 1987; Paumier et al. , 1986). Upgrades in new instrumentation
will include automated surface observation stations (ASOS), next generation
radar (NEXRAD), and remote profilers. Data dissemination will be improved
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with the operation of an automated weather interactive processing system
(AWIPS) and perhaps with a modern climatological data distribution system
(NOAANET). The focus of this report is to assess how these changes in NWS
meteorological data will affect EPA air pollution models. In particular,
this report is intended to inform model users and developers on likely
changes and to recommend upgrades in meteorological processors in order to
effectively accoraodate data from new instruments and in different formats.
In Section 2 of this report, current meteorological data requirements
for EPA air pollution models will be reviewed. Proposed changes to NWS
instrumentation and data dissemination will be discussed in Section 3,
especially as related to EPA models. A summary and recommendations are
given in Section 4.
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SECTION 2
CURRENT REQUIREMENTS
Air pollution models in EPA can be broken down into two basic areas:
UNAMAP models and regional models. In general, UNAMAP models are used by
the public for regulatory modeling. It is estimated that several hundred
organizations in the United States use UNAMAP models. Regional models
tend to be larger and more complicated than UNAMAP models. They are either
used for research and development or for planning emission reduction strate-
gies across several states. Models such as the regional model for acid
depostion (RADM) and the regional oxidant model (ROM) are being used in
making important policy decisions. Like UNAMAP models, their successful
operation depends on National Weather Service (NWS) meteorological data.
UNAMAP MODELS
UNAMAP stands for the User's Network for the Applied Modeling of Air
Pollution. It began in 1973 to provide the EPA modeling community ready
access to models for estimating air quality impact from proposed and exist-
ing sources of air pollution. The latest version of UNAMAP, version 6, was
released in 1986 and contains over 24 models and meteorological processors.
Version 6 contains both models that have regulatory status and models that
are to be tested and evaluated. Two UNAMAP models, PLUVUE-2 and MESOPUFF-2,
are regional-scale models. Attributes of each model are summarized in
Table 1.
The models listed in Table 1 are either short-term or long-term models.
Short-term models use hourly meteorological data to estimate air pollution
concentrations for time periods ranging from 1 hour to 1 day. Long-term
models use climatological frequency distributions of wind speed, wind
direction, and stability class to estimate air pollutant concentrations
for seasonal or yearly periods. Both types of models depend on National
Weather Service data for meteorological information.
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Table 1. Meteorological requirements for
6) models.
Model
Averaging time Meteorological
Format
BLP
RAM
ISCST
MPTER
CRSTER
MPTDS
COMPLEXI
CALINE-3
INPUFF
PEM-2
PLUVUE-2
HIWAY-2
PAL- 2
APRAC-3
PBM
MESOPUFF-2
TUPOS
SHORTZ
PTPLU-2
COM- 2
ISCLT
VALLEY**
LONGZ
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Long-term
Long-term
Long-term
Long-term
LJ1-\J\—^'&*J*-'J-
RAMMET
RAMMET
RAMMET
RAMMET
RAMMET
RAMMET
RAMMET*
none
none
none
none
none
none
none
PBMMET
READS 6/ ME SOPAC
MPDA
METZ
none
none
none
none
none
TD-1440/9689
TD-1440/9689
TD-1440/9689
TD-1440/9689
TD-1440/9689
TD-1440/9689
TD-1440/9689
Unique
Unique
Unique
Unique
Unique
Unique
Unique
TD-1440/9689
TD-1440/5600
TD-1440/5600/onsite
TD-1440/9689/ onsite
none-required
STAR
STAR
STAR
STAR
*RAMMET is a generic name for EPA short-term meteorological processors.
**Can also predict 24-hour average concentrations.
As shown in Table 1, many of the UNAMAP models use meteorological
data in special formats as available from the National Climatic Data Center
(NCDC) in Asheville, North Carolina. The four currently-used data formats
are summarized in Table 2. Descriptions of these data formats are contained
in the Appendices.
Table 2. Meteorological data formats used with UNAMAP (Version 6) models.
NCDC format
identifier
TD-1440
TD-5600
TD-9689
TD-9773
Description
Hourly surface observations
Twice-daily rawinsonde observations
Twice-daily mixing height estimates
STAR data — joint frequency distri-
butions of wind speed, wind direction,
stability class
Appendix
A
C
E
F
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Most short-term models require hourly surface and twice-daily mixing
height data in the TD-1440 and TD-9689 data formats. Before these models
can be operated, they depend on a meteorological program, called RAMMET, to
process the data.
The TD-1440 format is generated from surface observations reported on
WBAN forms. Variables included in the TD-1440 format are listed in Table
3. Only a few of these variables are currently used with the EPA meteoro-
logical processor as noted in Table 3. A complete description of the
TD-1440 format is given in Appendix A.
Table 3. List of variables in the the TD-1440 format.
Variable name Column
SFCID
YR
MONTH
DAY
HOUR
CEILHT
SKY
VISE
WX
PRESS
TDEW
WD
WS
S TAP RE
TEMP
TWET
RH
CLDS
OBSCUR
1
6
8
10
12
14
17
21
24
32
36
39
41
43
47
50
53
56
- 5
- 7
- 9
- 11
- 13
- 16
- 20
- 23
- 31
- 35
- 38
- 40
- 42
- 46
- 49
- 52
- 55
- 78
79
Description
WBAN 5 digit station number
Last two digits of year
01 = January, 12 = December
Day of month
Local standard time (00 - 23)
Ceiling ht. (hundreds of feet)
Sky condition (NOT USED)
Visibility (NOT USED)
Weather type (NOT USED)
Sea-level pressure (NOT USED)
Dew point temperature (NOT USED)
Wind direction (tens of degrees)
Wind speed (knots)
Station pressure (NOT USED)
Dry bulb temperature (F)
Wet bulb temperature (NOT USED)
Relative humidity (NOT USED)
Cloud information (NOT USED)
Total opaque sky cover (tenths)
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The TD-9689 format resulted from a study conducted by the EPA in
collaboration with the National Climatic Center (now NCDC). In the study,
reported by Holzworth (1972), twice-daily mixing heights and mean boundary
layer wind speeds were computed for a five year period for 62 stations
across the United States. The manner in which the twice-daily mixing
heights have been calculated is shown in Figure 1. Both mixing heights are
based on the 1200 GMT sounding. The morning mixing height, used only in
urban short-term modeling, is computed as being the height at which the
adiabat extending from the morning minimum temperature plus 5 C intersects
the 1200 GMT temperature sounding. The afternoon mixing height is deter-
mined by taking the afternoon maximum surface temperature and finding the
height at which its adiabat intersects the 1200 GMT sounding.
The UNAMAP models shown in Table 1 use these twice-daily values for
determining hourly mixing heights. The manner in which hourly mixing
heights are determined is shown in Figure 2. For rural applications, only
the afternoon value is used as described in EPA (1977). For urban appli-
cations, both the morning and urban mixing heights are determined from both
the morning and afternoon mixing heights as reported in TD-9689. The
National Climatic Data Center makes no provision for missing data, precipi-
tation, and cold advection. The user is therefore required to fill in
these data gaps before running a preprocessor such as RAMMET.
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Morning sounding (12 GMT)
Afternoon mixing height
Morning (urban) mixing
height
T,
n
Potential temperature
Figure 1. Determination of twice-daily mixing heights as used for TD-9689.
Tn is the morning minimum temperature, Tn +5 is the morning minimum
temperature plus 5 K, and Tx is the afternoon maximum temperature.
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PREVIOUS DAY
CURRENT DAY
FOLLOWING DAY
e>
H
a
Sunaet
Sunrise 1400 Sunset
Sunset
Sunrise 1400 Sunset
TIME
1400
1400
Figure 2. Determination of hourly mixing heights as used in UNAMAP short-term models.
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In recent years, models have been added to UNAMAP that use additional
information on the lower atmosphere in an attempt to simulate more accurate-
ly diffusion in the boundary layer. One example is the TUPOS dispersion
model (Turner et al. , 1986). TUPOS was especially designed to be compa-
tible with the new EPA Meteorological Processor for Dispersion Analysis
(MPDA) (Paumier et al. , 1986). MPDA specifies diffusion in greater detail
than the existing meteorological processor, RAMMET. It allows for on-site
data, missing data, and uses upper air, wind, and temperature data from the
twice-daily NWS radiosondes (as given in the TD-5600 format). The TD-5600
format consequently consists of more data than that available from the
TD-9689 format which has been traditionally used. A description of the
TD-5600 format is given in Appendix C. Other models that have special
provisions for on-site data include INPUFF, HIWAY-2, and SHORTZ. The
meteorological processor for SHORTZ handles on-site data but does not
handle missing data periods. These more advanced meteorological prepro-
cessors which handle missing data, on-site data, and available National
Weather Service data apparently represent future trends in UNAMAP models
and will be discussed in Sections 3 and 4.
Another sophisticated meteorological processor is included with MESO-
PUFF-2. It computes gridded values of meteorological information while
using hourly surface and twice-daily radiosonde data. Meteorological data
requirements for regional models such as MESOPUFF-2 will be discussed in
the next subsection.
Long-term models such as CDM-2 and ISCLT are used for making seasonal
and annual estimates of air quality. They rely on joint frequency distri-
butions of wind speed, wind direction, and stability class. These data
are usually obtained from NCDC in a format commonly known as STAR data.
Recently, these data were made available on PC diskette (Heira, 1987) in
format TD-9773. This format is described in Appendix F.
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REGIONAL MODELS
As mentioned above, two of the UNAMAP models, MESOPUFF-2 and PLUVUE-2,
are regional models. They require more data than the other UNAMAP models.
MESOPUFF-2 requires surface and upper-air data from many locations within
an area. Its meteorological preprocessor, MESOPAC, accepts data in the
TD-1440 and TD-9689 formats. PLUVUE-2 has similar data requirements except
it does not have a preprocessor for manipulating meteorological data into a
specific format.
Other regional models used by EPA include RELMAP, ROM, and RADM. Most
of these models are undergoing research and development, and their meteoro-
logical processors can be updated as new and improved meteorological data
become available. Their data needs currently are similar to MESOPUFF except
that RELMAP requires precipitation amounts for one degree latitude by one
degree longitude areas. RADM estimates precipitaton amounts using its own
dynamic prognostic meteorological model because adequate precipitation data
do not exist for objective analysis (NCAR, 1986).
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SECTION 3
PROPOSED NWS REVISIONS
The National Weather Service (NWS) is modernizing its observational
systems and data dissemination procedures. Existing NWS instrumentation
has not been significantly modified for 25 years and is rapidly approaching
obsolescence. Furthermore, the current observational process is quite
labor-intensive and requires a large expenditure of funds. Technology
now exists for automated measurements of surface and upper-air weather
variables. In addition, the advantages of Doppler radar have been clearly
demonstrated, especially for severe weather application (Durham and Wilk,
1987). These new systems will generate additional data that will require
enhanced data handling capabilities. The current AFOS system uses 1970s
technology and is overburdened in its data handling and processing require-
ments. Also, the National Climatic Data Center is striving to meet the
needs of new data formats and the increased amount of data that will be
collected in the near future.
This section examines these changes from the perspective of air pol-
lution modeling. First, instrument programs will be examined to see if
they offer any potential for air pollution model application. Then, changes
in data dissemination and data formats will be discussed.
INSTRUMENTATION
Advances are taking place in surface observations, upper-air obser-
vations, and radar. Current surface observation platforms will be replaced
by an Automated Surface Observation System (ASOS). The upper-air rawinsonde
system will be supplemented by remote profilers. Radars are being replaced
by Doppler radar in the next generation radar (NEXRAD) project. This section
examines the attributes of each of these systems.
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Automated Surface Observation System (ASOS)
The National Weather Service (NWS) plans for ASOS to be in operation
by the early 1990s. ASOS is the product of several years of research and
is a cooperative venture among several federal agencies. Development of an
automated surface observing systems was initiated by the Departments of
Commerce (DOC), Defense (DOD). and Transportation (DOT) in the early 1970s.
The promise of such a system became apparent in 1978 in a joint project by
the Federal Aviation Administration (FAA) and the NWS. Since 1984, the
ASOS project has been jointly funded by DOD, NWS, and FAA. Management and
operation of ASOS is being assumed by the NWS.
ASOS will be implemented in one of two levels, basic or unmanned. In
the unmanned level, ASOS systems will be installed at sites which currently
do not have a meteorological observation system. This includes many of the
general aviation facilities around the country. ASOS will therefore provide
extensive surface meteorological measurements at locations where very
little or no information has been available. In the basic level of service,
ASOS will be installed at existing weather reporting stations. Initially,
however, on-site observers will augment the system by reporting additional
cloud information and special remarks. At some locations, where an observer
is available less than 24 hours a day, ASOS will run in an unmanned mode
when the observer is not available. In all, about 1500 ASOS sites are
planned for the next 10 years.
To accomplish its objectives, ASOS uses recent advances in meteoro-
logical instrumentation. A laser ceilometer will replace the current 25
year old rotating beam ceilometer. The laser ceilometer can measure cloud
bases through precipitation and can detect cloud layers up to 12,000 feet.
Visibility measurements will be taken with a forward-looking visibility
meter. Observers consequently will not be required to estimate visibility,
which often varies from observer to observer and is difficult to estimate at
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night. With the eventual automation of ASOS, a laser weather identifier is
being developed. The current design employs a light-emitting diode weather
identifier (LEDWI). It projects a partially coherent light source over a
1 m baseline and measures the light's scintillation properties. The LEDWI
can discriminate between rain, snow, and drizzle and can estimate their
intensities. However, it can not discriminate between hail and ice pellets.
Other instruments being updated include the hygrothermometer and the wind
vane. The hygrothermometer, called HO-83, is based on a "cooled mirror"
approach. The wind vane is a new prop-vane designed by R. M. Young.
However, in preliminary tests, it has experienced problems associated with
icing and stalling, and design changes are pending.
ASOS will have the capability of storing data on-site and will connect
with the existing data dissemination network. Current plans are for hourly
data summaries to be stored on-site for 30 days and 1 minute data to be
stored up to 8 hours. ASOS will be integrated into the exisiting NWS net-
work, currently called AFOS. Later in the 1990s, the data will be dissemi-
nated via the automated weather interactive processing system (AWIPS).
Eventually, the data from ASOS will be archived at the National Climatic
Data Center.
Despite its advantages, ASOS poses potential shortcomings for air
pollution models. At unmanned sites, cloud information will be available
only to 12,000 feet. Current EPA meteorological processors require opaque
cloud cover for stability estimates. However, the ASOS program office
intends to maintain observers at primary locations so that certain infor-
mation such as the upper—level cloud cover can be reported. Unfortunately,
current plans by the NWS state that hourly values of meteorological varia-
bles will be based on only 2 minute data averages collected on the hour.
Since data will be sampled every minute, true hourly averages (especially
of winds) could be obtained at little additional cost. However, this
averaging and archival of hourly data requires a committment of funds that
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currently does not exist. In summary, ASOS represents a major change in
surface observations. Its deployment and operation should be watched care-
fully by those concerned with using surface observations in air pollution
models.
Rawinsondes
Since World War II, rawinsondes have been used to measure the vertical
structure of wind, temperature, moisture, and pressure in the atmosphere.
Although the system is well established, some minor improvements are being
implemented. Microprocessors are being installed at each rawinsonde site
which will automate data collection and perform many of the quality assurance
checks. This should result in greater data capture and improved data
quality. The microprocessors coupled with a redesign in the rawinsonde
package will yield more frequent measurements. Instead of every 60 seconds,
data will be archived every 30 seconds, thus providing improved resolution
of vertical measurements. Also, data measured every six seconds will be
archived at each site for up to six months. Special requests for six second
data, say for a field study, can be made through the Upper Air Programs
Office of the NWS.
Profiler
For years, rawinsondes have not provided upper-air data in a temporal
and spatial resolution desired by numerical weather prediction and air
pollution modelers. Currently, upper-air data are available every 12 hours
and only at selected stations. The profiler system is designed to fill in
these temporal and spatial data gaps for weather forecasting purposes.
The profiler is a ground-based remote sensing system designed to
measure wind, temperature, and moisture profiles above a given site during
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all weather conditions. It consists of two subsystems: a wind profiler and
a thermodynamic profiler. The wind profiler is a UHF (frequency currently
established at 405 MHz) clear-air radar which is sensitive to backscatter
from radio refractive-index irregularities caused by turbulence. Winds
with the profiler are determined from Doppler shifts of the backscattered
signal. The thermodynamic profiler used for measuring temperature and
moisture consists of six channels of a radiometer which measures thermally
emitted electromagnetic energy. More details on the profiler can be
obtained from Chadwick and Hassel (1987) and Hogg et al. (1983).
The profilers are undergoing operational development. The first oper-
ational profiler network is expected to begin operation in 1989. Initial-
ly, 31 sites have been established in which it is hoped to demonstrate the
feasiblity of the profiler. This demonstration network is expected to
operate until 1994, when the NWS hopes to implement a national network of
profilers. Currently, it is anticipated that the profilers will only
augment the current rawinsonde network. Ultimately, as the technology is
improved and field-tested, the profilers would be expected to replace the
labor-intensive rawinsonde system.
Like the ASOS program, the profiler network does pose some potential
problems for air pollution modelers. The lower limit of measurement for the
405 MHz wind profiler is 0.5 km. This limitation would be a detriment to
boundary layer models which require lower-level tropospheric winds. The
National Weather Service has indicated that it is considering to collocate
acoustic Doppler sounders along with the wind profilers to provide lower
level winds. However, these plans require further investigation. With the
thermodynamic profiler, temperature and moisture data will be measured up
from the surface, but the accuracy of these measurements will decrease with
height. Satellite sensing data is expected to augment this data at upper
levels. Preliminary tests of the radiometric data measurements indicate that
15
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while the temperature and moisture profiles are averaged quite accurately,
the radiometer fails to detect rapid changes in these parameters. Research
is continuing on how to integrate information from the wind profiler and
other data sources to the temperature and moisture readings. Therefore,
while it will be beneficial to have hourly vertical profiles of temperature
and winds, much work remains to be accomplished with the profiler to obtain
the data in sufficient vertical resolution for air pollution modeling.
NEXRAD
Another advanced system planned for deployment in the 1990s is the Next
Generation of Weather Radars (NEXRAD). Like ASOS, it is the culmination of
years of research in an effort by the DOC, DOD, and DOT to modernize instru-
ment systems. The NEXRAD program will have Doppler radars which will pro-
vide increased range and resolution of reflectivity patterns. The radars
also can estimate wind velocities within precipitating clouds. While their
primary purpose is for severe storm detection and tracking, their output
should assist in regional scale air pollution modeling.
Acquisition of the NEXRAD system was initiated by the NWS in 1980. In
September 1987, the NWS was scheduled to have selected a final contractor
to assume limited production of 10 units. These prototypes should be
delivered during 1989 - 1991. Full-scale production and installation of
NEXRAD at 165 sites is scheduled during 1990 - 1994.
Of the more than 25 meteorological products expected from NEXRAD, rain-
fall accumulation will probably most benefit air pollution modeling. NEXRAD
will provide rainfall rates in 2 km x 2 km areas. NCDC anticipates that it
will archive these gridded values for every 15 minutes. However, final
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archival requirements have not been established. Acid deposition models,
such as RADM, would particularly benefit from the relatively high-resolution
rainfall data.
DATA DISSEMINATION
Most users of EPA air pollution models rely on historical or climatic
data. These data have traditionally been obtained through the National
Climatic Data Center (NCDC) in Asheville, North Carolina. Near-real-time
meteorological data and forecast products are available from the National
Weather Service (NWS). Although NWS data are not usually accessed directly,
it is possible that users may begin to use real-time data for emergency
response applications.
This section primarily discusses changes in data dissemination related
to NCDC, but will also briefly review a new data acquistion system under
development by the NWS called AWIPS/NOAAPORT.
National Climatic Data Center
Most modelers of air pollution depend on the National Climatic Data
Center (NCDC) for meteorological data. Because of this reliance on NCDC,
it is important that renovations at NCDC be examined with respect to new
data formats and changes in operation.
The center each day handles hundreds of requests for data. Six staff
meteorologists interact with users to determine the data needs for each
user. The number of data requests and the amount of data continue to grow
at a staggering pace. The center handles over 20,000 requests for data per
year. It also has to maintain a tape library of over 30,000 magnetic tapes
which grows weekly. Because of this huge amount of data, NCDC has started
to modernize its operation.
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Modernization activites at NCDC include an increased use of Personal
Computers (PCs) and the introduction of the element format. The use of PCs
was recently discussed by Heim (1987). The primary motivation for going to
floppy diskettes as a means of transferring data was because of the demand
by the air pollution modeling community. Several data formats are available
on floppy diskette. These include TD-1440 surface data, TD-3280 surface
data, TD-9689 mixing height data, and TD-9773 STAR data. As PCs gain favor
among the air pollution modeling community, the sale of floppy diskettes
by NCDC will likely grow.
Thus far, the new element formats (TD-3280 and TD-6200) have not been
used in EPA air pollution modeling. Although they have been available since
1984, changes in computer codes for EPA meteorological processors take time
and money. However, discussions with NCDC have revealed that obtaining the
same data in TD-3280 format instead of TD-1440 reduces costs by about 40
percent. NCDC is basically set up on a cost reimbursable basis — they
charge what it costs them to generate the data. Because data are stored in
the element format, it is advantageous to obtain the data in the new format.
Besides, the new format is fairly easy to run, and only the variables
needed for modeling need be ordered. Descriptions of the new formats are
given in Appendices B and D.
The advent of new observational systems in the NWS present additional
challenges to NCDC. NCDC has made some effort on establishing formats for
NEXRAD and profilers. Archiving data for NEXRAD will be a problem because
of the amount of gridded data. The amount of data consists of gridded
values (for 1 km by 2 km areas) every 5-15 minutes for up to 25 variables.
Clearly, this is a large amount of data and needs to be maintained in a logi-
cal manner. Because profilers are still undergoing development, their data
are being stored by NOAA's Environmental Research Laboratory in Boulder,
Colorado. Eventually, the profiler data need to be added to the national
archive, but no arrangements for archiving the data have yet been made.
18
-------
As the size of the data bank continues to grow and if the center is
restricted to a small staff, a greater reliance will be placed on computer
technology to faciliate data transfer and processing orders. One idea
which has been discussed is establishing a modern climatological data
transfer system to be called NOAANET. The idea for such a system is that
it would allow the user to order data via terminals (without interacting
directly with people) and have the order filled either by electronic data
transfer or by software which uses artificial intelligence to generate a
magnetic tape or floppy diskette. Because the idea is preliminary, people
requesting data for at least the next five years will probably continue to
order data in the current manner.
AWIPS/NOAAPORT
A major component of the NWS's modernization is the development of an
Automated Weather Interactive Processing System (AWIPS). It is intended as
"an advanced data processing, display, and communications system" which
will replace AFOS (Boezi et al. , 1987). Although AWIPS will emphasize
forecasting and improved severe-weather warning capability, some of its
features may have a bearing on future air pollution modeling activities.
The design and installation of AWIPS is a five phase program. We are
currently nearing the end of the first phase entitled Requirements. In
March 1988, the NWS will select two contractors to participate in the
second phase System Definition. The third phase will be for Development,
and it is scheduled to begin in 1989. Deployment (Phase IV) is planned for
1991, and Full Operation (Phase V) is set to begin in early 1992.
19
-------
Major components of AWIPS will include the following:
o Acquire data and products from conventional and advanced observing
systems.
o Process and display data and guidance material for the forecaster.
o Extract and assimilate information and help the forecaster in pre-
paring warnings and forecasts.
o Serve the needs of external users by interacting with NOAAPORT.
NOAAPORT is expected to be of interest to air pollution model users.
When near-real-time meteorological data are needed, say for emergency
response models, NOAAPORT would likely provide the necessary meteorological
information. Also, NOAAPORT may be useful if information, for example from
NEXRAD or profilers, are not being archived into the national data base.
The specifications for NOAAPORT have not been defined, and interested
parties should monitor development of the AWIPS/NOAAPORT system over the
next few years.
20
-------
SECTION 4
SUMMARY AND RECOMMENDATIONS
This project began as an attempt to understand how data formats from
the National Climatic Data Center (NCDC) were changing and how these changes
would impact EPA's meteorological processors. While investigating these
changes, we learned of new advances in meteorological instrumentation and
data dissemination which potentially can benefit EPA's air pollution models.
For EPA to best accomodate the planned changes to NWS observation and
data dissemination programs and the planned changes to NCDC's data formats,
we offer the following recommendations:
(1) Recognizing that EPA's meteorological processors will need to be modi-
fied to handle new NCDC data formats, they should also be upgraded to in-
corporate our more advanced knowledge of diffusion meteorology. This up-
grade could also serve as a catalyst for incorporating more advanced modeling
techniques into air pollution models. It should be noted that such efforts
have begun with the development of the Meteorological Processor for Dif-
fusion Analysis (MPDA) (Paumier et al. , 1986) and the Turbulence Profile
Sigmas (TUPOS) model (Turner et al., 1986).
(2) EPA should encourage the collection of meteorological data specific to
diffusion modeling and should investigate the feasibility of collecting
some of these data at NWS sites. As recommended by an expert panel
(Hoffnagle et al., 1981), additional meteorological variables such as hori-
zontal fluctuations of wind direction (09), harmonic mean wind speeds,low-
level temperature gradients, and total solar radiation should be collected
for air pollution modeling. It is promising to note that EPA (1987) recent-
ly provided guidance for collecting some of these variables at on-site mea-
surement programs. Not all air pollution modeling applicants, however, will
have access to an extensive meteorological monitoring program and will have
21
-------
to depend on NWS data. Therefore, EPA should actively coordinate NWS
meteorological data collection programs through the Office of the Federal
Coordinator. In particular, it is advisable that EPA maintain vigorous
participation in the Working Groups for Automated Surface Observations,
Profiler Systems, and Radar Meteorological Observations. Perhaps with
funding from appropriate organizations and cooperation with the NWS, ad-
ditonal meteorological data for diffusion modeling can be collected at NWS
sites.
(3) The formatting and handling of meteorological data for regional-scale
models should be improved. Regional-scale models require vast amounts of
surface, upper-air, and satellite data. Because these models operate
sequentially, data must be sorted by hour. Unfortunately, NCDC data are
sorted by station and not by hour. Consequently, much effort goes into
generating a data set in the appropriate format. Two options which could
be investigated include the development of a new NCDC data format and direct
access and storage of NWS observations by EPA.
(4) The Environmental Operations Branch (BOB) should maintain active com-
munication with NCDC. In performing this study, it became quite apparent
that NCDC is willing to be responsive to the needs of the air pollution mod-
eling community. By improving communication with NCDC, EOB can more effec-
tively inform users about changes in data formats. One possibility is to
develop a users' guide describing meteorological data requirements for
UNAMAP models. The guide would also provide information on how to order
meteorological data from NCDC, and it could serve as a valuable reference
manual for NCDC meteorologists when dealing with air pollution modeling
clients.
22
-------
REFERENCES
Boezi, L.J., H.L. Schmidt, and W.L. Murray, (1987): Advanced weather interac-
tive processing system for the 1990's (AWIPS-90). Preprint, Third Inter-
national Conference on Interactive Information and Processing Systems
for Meteorology, Oceanography, and Hydrology, January 12-16, 1987- New
Orleans, American Meteorological Society, pp. 6-7.
Chadwick, R.B., and N. Hassel (1987): Profiler: the next generation surface-
based atmospheric sounding system. Preprint, Third International Confer-
ence on Interactive Information and Processing Systems for Meteorology,
Oceanography, and Hydrology, January 12-16, 1987. New Orleans, American
Meteorological Society, pp. 15-21.
Durham, A.F., and K.E. Wilk (1987): NEXRAD - the nation's next generation
radar. Preprint, Third International Conference on Interactive Infor-
mation & Processing Systems for Meteorology, Oceanography, and Hydrology,
January 12-16, 1987. New Orleans, American Meteorological Society, pp.
11-14.
Heim, R. (1987): Climatological data available on diskette. Paper 87-109.6
presented at the 80th Annual Meeting of the Air Pollution Control Assoc-
iaton, New York, June 20-26, 1987. 10 p.
Hoffnagle, G. , M. Smith, T. Crawford, and T. Lockhart (1981): On-site meteoro-
logical instrumentation requirements to characterize diffusion from point
sources - a workshop, 15-17, January 1980, Raleigh, NC. Bull. Am. Meteor.
Soc. , (52, pp. 255-261.
Hogg, D.C., M.T. Decker, P.O. Guiraud, K.B. Earnshaw, D.A. Merritt, K.P.
Moran, W.B. Sweezy, F.G. Strauch, E.R. Westwater, and G.G. Little (1983):
An automatic profiler of temperature, wind, and humidity in the tropo-
sphere. J. Climate and Appl. Meteor, 22, pp. 807-831.
Holzworth, G.C. (1972): Mixing heights, wind speeds, and potential for urban
air pollution throughout the continguous United States. Office of Air
Programs Pub. No. AP-101. United States Environmental Protection Agency,
Research Triangle Park, NC. 118 p.
National Center for Atmospheric Research (1986): Preliminary evaluation
studies with the regional acid deposition model (RADM). EPA/600/3-86/
024, U.S. Environmental Protection Agency, Research Triangle Park, NC.
198 p.
Paumier, J. , D. Stinson, T. Kelly, C. Bollinger, and I. Irwin (1986): MPDA-1:
A meteorological processor for diffusion analysis. EPA/600/8-86/011,
U.S. Environmental Protection Agency, Research Triangle Park, NC, 192 p.
[Available from NTIS as PB86-171-402/AS].
23
-------
Turner, D. B. , T. Chico, and J. A. Catalano, 1986: TUPOS - A multiple
source Gaussian dispersion algorithm using on-site turbulence data.
EPA/600/8-86/010, U. S. Environmental Protection Agency, Research
Triangle Park, NC. 171 p. [Available only from NTIS, accession
number PB86-181-310/AS].
U.S. Environmental Protection Agency (1977): User's manual for single-source
(CRSTER) model. EPA/450/2-77/013, Research Triangle Park, NC. 279 p.
U.S. Environmental Protection Agency (1987): On-site meteorological program
guideline for regulatory modeling applications. EPA/450/4-87/013,
Research Triangle Park, NC, 192 p.
24
-------
APPENDIX A
DESCRIPTION OF THE TD-1440 FORMAT
This description is reproduced from documentation provided by the National
Climatic Data Center (NCDC).
25
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
INTRODUCTIOK
SOURCE
Weather observations, in support of aircraft operations, have been taken at airports since the earliest
days of aviation. The rapid growth of the industry during the 1940's made it evident that some mechanical
means of summarizing the data must be developed. Hov was a site to be selected or an airport designed
without adequate statistical information on which to base decisions? The first efforts toward this end
caused the WEAN No. 1 card to come into being. For archiving purposes these observations, mostly from
military stations, were designated as Card Deck-141. The period of record is generally 1941-1944. A
change of format necessitated a new card deck designation (Card Deck-142) to be instituted in 1945.
This deck remained in force into 1948. During 1948 additional major changes were made in observing and
recording practises. These led to the development of Card Deck-144. Although the usual beginning
data of digital information in this form is June 1948 the changeover was made station by station on
varying dates. Then too, some stations have had observations back-punched in this format to much
earlier dates.
In the early 1960's the FAA undertook a major airport study. To facilitate the handling of large
masses of data necessary for this effort the Climatological Services of the Weather Bureau, Air Force
and Navy along with the FAA devised the tape format described in this manual. This format was called
Tape Data Family-14 (TDF-14) to retain some continuity with the card decks. Within this family of
similar observations there are several Tape Decks each one uniquely identified at the beginning of
each physical record on tape.
Beginning January 1, 1965, for most National Weather Service stations and March 1, 1972, for most Naval
Weather Service stations the digitizing of the Airways Observations was reduced from 24 obs/day to
8 obs/day. These observations, at 3-hourly intervals, coincide with the normal GKT schedule of OOZ,
03Z, 06Z etc. This means, of course, that the observations, keyed in Local Standard Time (LST)
differ according to time zone.
Oct 1975
26
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
ii
QUALITY CONTROL AMD CONVERSIONS
All observations have been subjected to some form of quality control. During the earlier years this was
almost entirely a manual effort. As more sophisticated techniques of processing were introduced the
quality control procedures were also improved. Today, the quality control effort is a blend of several
computer programs and manual review. Observations are checked for conformance to established observing and
coding practises, for internal consistancy, for serial, or time oriented consistency, and against
defined limits for various meteorological parameters.
The archiving of long term climatological information presents an almost constant dilemma to the archivist,
systems analyst and programmer. Refinements of observational instruments, new techniques, changes
in user needs and other factors combine to keep the incoming data in an almost perpetual state of
change. In some instances the changes are of such significance that individual fields in the tape
format must be redefined and the ultimate user must adapt this new information to his needs.
At other times the changes may be of such a nature that they can be incorporated into the existing
format by converting units or other measurements. For example, wind speeds were recorded and punched
in miles per hour through 1955 and in knots thereafter. All wind speeds on the.tape file are in knots,
the earlier period having been converted from mph.
USE OF THE MANUAL
This manual was designed so that recourse to additional reference material should be unnecessary.
Occasionally, however, the researcher may wish to obtain a copy of the original Card Deck reference
manual. This may be done by writing to the Director, National Climatic Center, Federal Building,
Asheville, NC 28801.
Care should be taken to read carefully the general tape notations and coding practises.
Oct 1975
27
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
ill
MANUAL AND TAPE NOTATIONS
FORMAT
Each physical tape record contains six observations and is 495 bytes long. These records consist of
15 bytes of identification folloved by six logical records of 80 bytes each. Records always begin with
the Local Standard Time hour of OOLST, 06LST, 12LST or 18LST. Thus, four physical records are needed to
contain each day's observations.
Space is always retained on tape for 24 obs/day. When no observation is available the hour is Indicated
(2 bytes) and all other fields are coded blank. Care in programing should be taken to allow for this
condition, particularly with most tapes from 1965 onward.
The manual presents a graphical representation of the standard format indicating Tape Fields, Tape
Positions and Element Definition followed by detailed information for each field.
Also included as part of the manual is a simple FORTRAN program that may be used to overcome the
problems of alphanumeric characters.
MANUAL AND TAPE
The following notations are used throughout the manual:
x - any numeric or alphanumeric character
i * same as x but used to show that the character is an indicator rather than part of the
recorded element
- an "11" or zone punch
+ - a "12" punch
both the and the + may appear by themselves or in combination with a numeric digit to
indicate an overpunch or signed field
A - blank
* • an 11,8,4 punch
* Currently, archive tapes are 9 track, 1600 bpi, blocked four (495x4-1980 bytes) and can be
furnished with this blocking factor if requested. The advantage is that the entire period of
record for one station can be provided on one reel of tape.
Oct 197S
28
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
iv
SPECIAL NOTE
The observations described in this manual are those from Card Deck-144. The Tape Deck number
is 1440. Elements for certain fields may differ in other Decks within this Tape Data Family.
Requesters of data other than TD-1440 will be furnished appropriate reference material.
Oct 1975
29
-------
TAPE DECK
1440
PAGE NO.
AIRWAYS SURFACE OBSERVATIONS
Oct 1975
CHARACTER SET TDF-14
HEXADECIMAL
1
2
3
4
5
6
7
8
9
0
A (blank)
*
4
A
B
C
D
E
F
G
E
I
J
K
L
M
N
0
P
Q
R
Fl
F2
F3
F4
F5
F6
F7
F8
F9
FO
40
60
5C
50
Cl
C2
C3
C4
C5
C6
C7
C8
C9
Dl
D2
D3
D4
D5
D6
D7
D8
D9
CO
DO
EO
OCTAL
01
02
03
04
05
06
07
10
11
12
20
40
54
60
61
62
63
64
65
66
67
70
71
41
42
43
44
45
46
47
50
51
72
52
32
EQUIVILANT CARD PUNCH
COMBINATION
1
2
3
4
5
6
7
8
9
0
blank
11
11,8,4
12
12,1
12,2
12.3
12.4
12,5
12,6
12,7
12,8
12,9
11,1
11,2
11.3
11.4
11.5
11,6
11,7
11,8
11,9
12,0
11,0
0,2,8 (record mark)
30
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
FORTRAN SUBROUTINE FOR SIGNED FIELDS
SUBROUTINE SIGNCK (IFLD,ISGN)
C THIS SUBROUTINE WILL TEST ANY WIND SPEED OR PSYCHROMETRIC WITH A SIGN OVER UNITS POSITION
C READ AS Al, AND THE HIGH ORDER POSITIONS READ AS AN I SPEC OF PROPER WIDTH.
C THE SIGN SHOULD ENTER THE PARAMETER LIST AS ISGN, THE REMAINING PORTION AS
C IFLD. UPON RETURN FROM THIS ROUTINE, THE VALUE OF THE FIELD WILL BE AN INTEGER
C WITH PROPER SIGN. IT WILL BE THE USER RESPONSIBILITY TO CONVERT THIS TO REAL
C FORM WITH PROPER DECIMAL ALIGNMENT. INVALID CONDITION CAUSES IFLD TO BE
C SET TO 9999.
DIMENSION IP(10),MIN(IO),NUM(10)
DATA IP/'A'.'B'.'C'.'D'.'E'.'F'.'G'.'H'.'I'.'oV
DATA MDi/'J'.'K'.'L'.'M'.'N'.'O'.'P'.'Q'.'R'.'o'/
DATA NUM/1,2,3,4,5,6,7,8,9,07,LAST/'*1 /
IF (ISGN.EQ.LAST) GO TO 16
DO 14 K-1,10
IF (ISGN.EQ.IP(K)) GO TO 20
IF (ISGN.EQ.MIN(K)) GO TO 22
14 CONTINUE
16 IFLD- 9999
RETURN
20 IFLD- IFLD*10 + NUM(K)
RETURN
22 IFLD- -(IFLD*10 + NUM(K))
RETURN
END
Oct 1975
31
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
vii
TAPE DECKS WITHIN TDF-14
TAPE DECK NAME OF CARD DECK
1400 L'SWB Form 1130-Aero Hourly Surface Observations
1410 USAF Form 94-A Hourly Surface Observations
1411 Hourly Ceiling-Visibility Observations (Card 1)
1412 Canadian Hourly Surface Observations (Type 141)
1420 WEAK Hourly Surface Observations, 1945-1948
1422 Canadian Hourly Surface Observations (Type 142)
1440 WBAN Hourly Surface Observations, 1945-
1441 Hourly Ceiling-Visibility Observations (Card 2)
1442 Canadian Hourly Surface Observations (Type 144)
1443 Canadian Hourly Surface Observations, 1950-
1445 Metar Observations
1480 Turkish Hourly Observations
1481 British Hourly Observations
1482 Azores Hourly Observations
1483 Korean Hourly Observations (ROK)
1484 Taichung Hourly Observations
1485 German Hourly Observations (GZMO)
1486 Chinese i Formosan Hourly Observations
Oct 1975
32
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
FIELD
NUMBER
TAPE
DECK
14XX
STN
NUMB
xxxxx
YR
XX
MO
XX
DY
XX
HR
XX
CEIL
iXXX
VIS
iXXX
WIND
DR
XX
SPD
XXX
DRY
BLE
XXX
WET
BLB
XXX
DEW
FT
XXX
REL
HUM
iXXX
S.L.
PRESS
XXXXX
STA
PPES
XXXX
SKY
COND
iXXXX
T
0
T
X
0
p
Q
X
CLOUDS
LAYER 1
A
M
T
X
T
Y
P
X
HGT
XXX
LAYER 2
A
M
T
X
T
Y
P
X
HGT
XXX
S
U
H
X
LAYER 3
A
M
T
X
T
Y
P
X
HGT
XXX
S
U
M
X
LAYER 4
A
M
T
X
T
Y
P
X
HGT
XXX
WEATHER
T
D
K
X
L Q
P P
X
X
F R Z
P C P
X
X
X
0 B
V S
X
X
W D
D R
X X
BLK
AAA
R
M
+
HP.
XX
CEIL
iXXX
WEATHER
T
H
D
X
L Q
P P
X
X
F
P
X
R Z
C P
X
X
0 B
V S
X
X
WD
DR
XX
BLK
AAA
K
M
+
FIELD
NUMBER
TAPE
FIELD NUMBER
001
002
003
004
005
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
TAPE
POSITIONS
001
005
010
012
014
016
018
022
026
028
031
034
037
040
044
049
053
058
059
060
061
062
065
066
067
070
071
072
073
076
077
078
079
082
083
084
085
086
087
088
004
009
Oil
013
015
017
021
025
027
030
033
036
039
043
048
052
057
- 064
069
075
081
ELEMENT
TAPE DECK NUMBER
STATION NUMBER
YEAR
MONTH
DAY
HOUR
CEILING HEIGHT AND INDICATOR
HORIZONTAL VISIBILITY AND INDICATOR
WIND DIRECTION - 16 POINTS
WIND SPEED
DRY BULB (AIR) TEMPERATURE
WET BULB TEMPERATURE
DEW POINT TEMPERATURE
RELATIVE HUMIDITY AND INDICATOR
SEA LEVEL PRESSURE
STATION PRESSURE
SKY CONDITION AND INDICATOR
TOTAL SKY COVER
TOTAL OPAQUE SKY COVER
AMOUNT OF LOWEST CLOUD LAYER
TYPE OF LOWEST CLOUD OR OBSCURING PHENOMENA
HEIGHT OF BASE OF LOWEST CLOUD LAYER OR OBSCURING PHENOMENA
AMOUNT OF SECOND CLOUD LAYER
TYPE OF CLOUD - SECOND LAYER
HEIGHT OF BASE OF SECOND CLOUD LAYER
SUMMATION AMOUNT OF FIRST TWO CLOUD LAYERS
AMOUNT OF THIRD CLOUD LAYER
TYPE OF CLOUD THIRD LAYER
HEIGHT OF BASE OF THIRD CLOUD LAYER
SUMMATION AMOUNT OF FIRST THREE CLOUD LAYERS
AMOUNT OF FOURTH CLOUD LAYER
TYPE OF CLOUD - FOURTH LAYER
HEIGHT OF BASE OF FOURTH CLOUD LAYER
OCCURRENCE OF THUNDERSTORM, TORNADO OR SQUALL
OCCURRENCE OF RAIN, RAIN SHOWERS OR FREEZING RAIN
OCCURRENCE OF RAIN SQUALLS, DRIZZLE OR FREEZING DRIZZLE
OCCURRENCE OF SNOW, SNOW PELLETS OR ICE CRYSTALS
OCCURRENCE OF SNOW SHOWERS, SNOW SQUALLS OR SNOW GRAINS
OCCURRENCE OF SLEET, SLEET SHOWERS OR HAIL
OCCURRENCE OF FOG, BLOWING DUST, OR BLOWING SAND
Oct 1975
33
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
2
TAPE
FIELD NUMBER
136
137
138
139
201 - 239
301 339
401 439
501 539
601 639
TAPE
POSITIONS
089
090 - 091
092 094
095
096 175
176 - 255
256 - 335
336 - 415
416 - 495
ELEMENT
OCCURRENCE OF SMOKE, HAZE, SMOKE AND HAZE, DUST, BLOWING SNOW,
BLOWING SPRAY
WIND DIRECTION - 36 POINTS
BLANK
RECORD MARK
SECOND OBSERVATION)
THIRD OBSERVATION )
FOURTH OBSERVATION)
FIFTH OBSERVATION )
SIXTH OBSERVATION )
THESE OBSERVATIONS FOLLOW
THE SAME FORMAT AS FIELDS
101-139 (TAPE POSITIONS
016-095).
Oct 1975
34
-------
TAPE DEPK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
TAPE TAPE
FIELD NUMBER POSITIONS
001
002
003
004
005
101
1021
001 - 004
005 009
010 Oil
012 - 013
014 - 015
016 017
018
102
019 - 021
ELEMENT
TAPE DECK NUMBER
STATION NUMBER
YEAR
MONTH
DAY
HOUR
CEILING HEIGHT
INDICATOR
CEILING HEIGHT
1031
022
VISIBILITY INDICATOR
TAPE CODE DEFINITIONS
CONFIGURATION AND REMARKS
1400 - 1499 Used to distinguish different
data sources. See current list
at beginning of manual.
01001 - 98999 Unique number used to identify
each station. Usually a WEAN
number but occassionally a
WHO number.
00 - 99 Year of observation.
00-99 - 1900-1999
01 - 12 Month of observation.
01-12 « Jan. - Dec.
01 31 Day of month.
00 23 Hour of observation in local
standard time.
00-23 = 0000-2300 LST
1,2,3,- These codes indicate various
&,A,A schemes used to convert ceiling
heights to hundreds of feet or
to indicate special conditions
of little or no meaning to the
general user.
000 - 800 Ceiling in hundreds of feet.
888, 999 Ceiling is defined as sky cover
AAA, AA* of .6 or greater.
000-800 - 00000-80,000 feet
888 - Ceiling of cirroform
clouds at unknown
height. Used for the
period Sep. 1956-
March 1970.
999 = Unlimited ceiling
AAA = Unknown
AA* = Original value invalid
0-5 These codes indicate various
M, A schemes used to convert
visibilities into statute miles
and have little or no meaning
to the general user.
Oct 1975
35
-------
TAPE DECK
AIRWAYS SURFACE OBSERVATIONS
PAGE
TAPE
FIELD NUMBER
103
TAPE
POSITIONS
023 025
ELEMENT
HORIZONTAL VISIBILITY
TAPE
CONFIGURATION
000-990
999
(Not all
values used)
AAA
AA*
104
026 027
WIND DIRECTION 16 POINTS
00-88
AA, A*
CODE DEFINITIONS
AND REMARKS
Prevailing horizontal visibility
(usually at an elevation of 6
feet above the ground) in
statute miles.
000
001
002
003
004
005
006
007
008
009
010
012
014
016
017
018
019
020
024
027
- Zero visibility
• 1/16 Statute miles
- 1/8
- 3/16
- 1/4
- 5/16
- 3/8
- 1/2
- 5/8
• 3/4-7/8
• 1
- 1 1/8
- 1 1/4
3/8
1/2
5/8
3/4
1/4
1/2
030-150 - 3-15 miles in
increments of one mile
200-950 - 20-95 miles in
increments of five
miles
990 - 100 miles or greater
999 • Unlimited
AAA • Unknown
AA* • Original value invalid
Direction from which the wind
is blowing in special 16 point
WBAN code.
11
12
22
32
33
34
44
54
55
56
66
76
77
78
88
18
00
AA
A*
Note:
North
North-Northeast
Northeast
East-Northeast
East
East-Southeast
Southeast
South-Southeast
South
South-Southwest
Southwest
West-Southwest
West
West-Northwest
Northwest
North-Northwest
Calm
Unknown
Original value
349°-011°
012°-033°
034°-056°
057°-078°
079°-101°
102°-123°
124°-146°
147°-168°
169°-191°
192--213"
214°-236°
237°-258°
259°-281"
282°-303"
304°-326°
327°-348"
invalid
Oct 1975
Beginning Jan 1, 1964
wind directions were
observed and coded to tens
of degrees (see field 137).
These values were converted
to the 16 point code.
36
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
TAPE
FIELD NUMBER
105
TAPE
POSITIONS
028 - 030
ELEMENT
WIND SPEED
TAPE
CONFIGURATION
+ +
000 199
AAA, AA*
106
107
108
031 033
034 036
037 039
DRY BULB (AIR) TEMPERATURE
WET BULB TEMPERATURE
DEW POINT TEMPERATURE
001 130
00$ 14$
AAA AA*
1091
040
RELATIVE HUMIDITY INDICATOR
4, A
109
110
041 043
044 - 048
RELATIVE HUMIDITY
SEA LEVEL PRESSURE
111
049 052
STATION PRESSURE
CODE DEFINITIONS
AND REMARKS
Wind speed in whole knots.
AAA " Unknown
AA* • Original value invalid
Note: When this field is numeric
it is always signed
positive (12 over punch).
Specified temperature in whole
degrees fahrenheit.
OOl - 130 - -1° -130°F
00$ - 14$ 0" - +140°F
AAA » Unknown
AA* - Original value
invalid
Note: When these fields are
numeric they are always
signed to indicate negative
(11 overpunch) or positive
(12 overpunch) temperatures
& • Used to denote that dew point
temperatures and relative
humidities were originally
coded with respect to ice
when temperature was below
32°F but were recomputed
with respect to water.
A • No special conversions made.
001 100 Relative humidity in whole
AAA, AA* percent.
AAA • Unknown
AA* • Original value invalid.
09000 - 10999 Pressure, reduced to sea level,
AAAAA, AAAA* in millibars and tenths.
09000-10999 - 900.0 - 1099.9 mb
AAAAA • Unknown
AAAA* - Original value
invalid.
1900 3999 Pressure at station level in
AAAA, AAA* inches and hundredths of Kg.
1900-3999 - 19.00 - 39.99 in Hg.
AAAA " Unknown
AAA* • Original value
invalid.
Oct 1975
37
-------
TAPE
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
TAPE TAPE
FIELD NUMBER POSITIONS
1121
053
ELEMENT
SKY CONDITION INDICATOR
112
054
057
SKY CONDITION
TAPE CODE DEFINITIONS
CONFIGURATION AND REMARKS
-, A Indicator of method of recording
Bky condition or other phenomena.
• Sky condition U.S. stations
prior to June 1951.
A • Sky conditions - U.S. stations
June 1951 and later.
Note: Some other decks have
various configurations
in this position denoting
deviation from standard
coding. Detailed Infor-
mation will be supplied
when applicable.
A descriptive symbolic coding
of the state of the sky,
referring in general to the
amount of the celestial dome
covered by clouds or obscuring
phenomena. There was a major
change in the method of recording
this field in Jume 1951.
When used to describe the amount
of sky cover alphanumeric
characters in this field have
the following meaning:
0 • Clear or less than .1 cover
1 • Thin scattered clouds .1 .5
2 - Scattered clouds .1 .5
3 - Dark scattered clouds .1 .5
4 • Thin broken clouds .6 ,9
5 - Broken clouds .6 .9
6 - Dark broken clouds .6 .9
7 « Thin overcast clouds 1.0
8 • Overcast clouds 1.0
9 ™ Dark overcast clouds 1.0
- • Obscuration
A " Partial obscuration
PRIOR TO JUNE 1951
During this period when scattered
clouds were reported the two
middle figures of the field
represent the height, in hundreds
of feet, of the lowest layer of
scattered clouds.
During this period only two layers
were recorded in this field. The
first digit always represents
the higher layer and the last
digit the lowest layer.
The codes on page 7 describe the
Sky Condition configurations that
appear on tape prior to June
1951. Tape configurations for the
period July 1951 onward are
explained on page 8.
Oct 1975
38
-------
TAPE PEEK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
TAPE
FIELD NUMBER
112
TAPE
POSITIONS
054 057
ELEMENT
SKY CONDITION
TAPE
CONFIGURATION
CODE DEFINITIONS
AND REMARKS
0 ™ Obscuration occurring alone
0—0 = Clear or less than .1 cover
0—A • Thin obscuration reported alone
0—4 to 0—9 » One layer of broken or overcast
clouds reported
4 to 9 - Obscuration with higher layer
of broken or overcast clouds
4—A to 9—A • Thin obscuration with higher
layer of broken or overcast
clouds
A—4 to A—9 - Layer of broken or overcast
clouds with thin obscuration
above
4—4 to 9—9 = TWO layers of broken or
overcast clouds
«• Two layers of obscuration
phenomena
A » Thin obscuration with
obscuration above
£ * Obscuration with thin
obscuration above
A—A - Thin obscuration with thin
obscuration above
4 to 9 » Layer of broken or overcast
clouds with obscuration above
0001 to 0993 • Layer of scattered clouds
1001 to 9993 " Layer of scattered clouds
with scattered, broken or
overcast layer above
-001 to -993 - Layer of scattered clouds
with obscuration above
A001 to A993 • Layer of scattered clouds
with thin obscuration above
**** . Original value invalid
AAAA = Unknown
For the two middle digits:
00 - 98 = Height of the lowest scattered
layer in hundreds of feet
99 = 10,000 feet or greater
— = No low scattered clouds
AA ~ Unknown
*A, A*, ** • Original value invalid
Cct 1975
39
-------
TAPE DECK
1440
AIEWAYS SURFACE OBSERVATIONS
PAGE NO.
TAPE
FIELD NUMBER
112
TAPE
POSITIONS
054 057
ELEMENT
SKY CONDITION
TAPE
CONFIGURATION
0000 - 9999
****
AAAA
113
114
115
118
122
126
058
059
060
065
071
077
TOTAL SKY COVER
TOTAL OPAQUE SKY COVER
AMOUNT OF LOWEST
CLOUD LAYER
AMOUNT OF SECOND
CLOUD LAYER
AMOUNT OF THIRD
CLOUD LAYER
AMOUNT OF FOURTH
CLOUD LAYER
116
119
123
127
061
066
072
078
TYPE OF LOWEST CLOUD OR
OBSCURING PHENOMENA
TYPE OF CLOUD-SECOND LAYER
TYPE OF CLOUD-THIRD LAYER
TYPE OF CLOUD-FOURTH LAYER
0-9, -
K,M,N,0
P.R.A
CODE DEFINITIONS
AND REMARKS
Beginning June 1951 sky condition
was reported and coded by layer
in ascending order. This allows
four layers to be described
because heights of scattered
clouds are no longer entered.
Individual sky condition
characters have the same meaning
(0-9, A, -) as those described
on page 6. If less than four
layers are present the remaining
positions are coded 0.
Example:
2580 = Three layers of clouds
lower scattered, broken
layer and higher overcast
AAAA = Unknown
**** = Original value invalid
Amount of the celestial dome
covered by clouds or obscuring
phenomena. Opaque means clouds
or obscuration through which
the sky or higher cloud layers
cannot be seen.
0 « Clear or less than .1
1-5 » .1 to .5 covered (scattered)
6-9 ™ .6 to .9 covered (broken)
- > .9 covered (overcast)
A - Unknown
Note: When cloud amount for
individual layers is less
than one tenth, the height
field may appear as the
actual height of the
fragment or as an invalid
(AA*) configuration.
Generic cloud type or obscuring
phenomena.
0 • None
1 - Fog
2 • Stratus
3 » Stratocumulus
4 • Cumulus
5 ~ Cumulonimbus
6 • Altostratus
7 " Altocumulus
8 - Cirrus
9 " Cirrostratus
K • Stratus Fractus
M • Cumulus Fractus
N » Cumulonimbus Mamma
0 • Nimbostratus
P • Altocumulus Castellanus
R ™ Cirrocumulus
• Obscuring phenomena other
than fog
A • Unknown
Oct 1975
40
-------
TAPE DEfK
1440
AIRWAYS SURJACE OBSERVATIONS
PAGE NO.
TAPE TAPE
FIELD NUMBER POSITIONS
117
062 - 064
120 067 069
124 073 - 075
128 079 - 081
ELEMENT
HEIGHT OF BASE OF LOWEST
CLOUD LAYER OR OBSCURING
PHENOMENA
HEIGHT OF BASE OF SECOND
CLOUD LAYER
HEIGHT OF BASE OF THIRD
CLOUD LAYER
HEIGHT OF BASE OF FOURTH
CLOUD LAYER
TAPE
CONFIGURATION
000 - 800
AAA
AA*
121
125
129
070
076
082
SUMMATION AMOUNT OF FIRST
TWO CLOUD LAYERS
SUMMATION AMOUNT OF FIRST
THREE CLOUD LAYERS
OCCURRENCE OF THUNDERSTORM,
TORNADO OR SQUALL
0 9
-. A
0-6
A
*
130
083
OCCURRENCE OF RAIN, RAIN
SHOWERS OR FREEZING RAIN
Oct 1975
CODE DEFINITIONS
AND REMARKS
Height of base of clouds or
obscuring phenomena in hundreds
of feet.
000-800 • 0 - 80,000 feet
888 • Cirroform clouds of
unknown height
• Partial obscuration
when field 116 coded
- or 1. Otherwise
indicates rone or no
clouds for which height
could be reported.
AAA <• Unknown
AA* Original value invalid
Total amount of sky covered by
the indicated layers.
0 ™ Clear or less than .1
1-9 • .1 to .9 covered
= > .9 covered
A » Unknown
0 » None
1 - Thunderstorm - lightning
and thunder. Kind gusts
less than 50 knots, and hail,
if any, less than 3/4 inch
diameter.
2 = Heavy or severe thunderstorm -
frequent intense lightning
and thunder. Wind gusts 50
knots or greater and hail, if
any, 3/4 inch or greater
diameter.
3 - Report of tornado or
waterspout.
4 - Light squall (through 5/51
only)
5 - Moderate squall
6 Heavy squall (through 5/51
only)
Note: Beginning June 1951 only
moderate squall is recorded
Squall is sudden increase
of wind speed by at least
16 knots, reaching 22
knots or more and lasting
for at least one minute.
A = Unknown
* - Original value invalid
0 • None
1 - Light rain
2 - Moderate rain
3 " Heavy rain
4 • Light rain showers
5 • Moderate rain showers
6 • Heavy rain showers
7 - Light freezing rain
8 » Moderate freezing rain
9 " Heavy freezing rain
A = Unknown
* - original value invalid
41
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
ID
TAPE TAPE
FIELD NUMBER POSITIONS
130
131
083
084
ELEMENT
OCCURRENCE OF RAIN, RAIN
SHOWERS OR FREEZING RAIN
OCCURRENCE OF RAIN SQUALLS,
DRIZZLE OR FREEZING DRIZZLE
132
085
OCCURRENCE OF SNOW,
SNOW PELLETS OR ICE CRYSTALS
TAPE CODE DEFINITIONS
CONFIGURATION AND REMARKS
Light - Trace (< .OOSin.) to
.10 inches per hour
Moderate = .11 to .30 inches
per hour
Heavy = > .30 inches per hour
0-9 0 = None
A 1 " Light rain squalls
* 2 = Moderate rain squalls
3 = Heavy rain squalls
See note under field 129.
Beginning Jan 1949 squalls
were reported separately
and these figures should
not appear thereafter.
4 = Light drizzle
5 " Moderate drizzle
6 = Heavy drizzle
7 = Light freezing drizzle
8 » Moderate freezing drizzle
9 = Heavy freezing drizzle
i ~ unknown
* « Original value invalid
When drizzle or freezing
drizzle occurs with other weather
phenomena:
Light - Trace (< .005 in) to .01
inches per hour
Moderate = > .01 to .02 inches
per hour
Heavy = > .02 inches per hour
When drizzle or freezing drizzle
occurs alone:
Light • Visibility 5/8 mile
or greater
Moderate - Visibility 5/16 1/2
mile
Heavy - Visibility 1/4 mile or
less
0-9 0 = None
A 1 Light snow
* 2 • Moderate snow
3 = Heavy snow
4 * Light snow pellets
5 • Moderate snow pellets
6 » Heavy snow pellets
7 = Light ice crystals
8 - Moderate ice crystals
9 ™ Heavy ice crystals
A tt Unknown
* ™ Original value invalid
Beginning April 1963 any
occurrence of ice crystals is
recorded as an 8. Prior to
this date intensities were
reported.
Oct 1975
42
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
11
TAPE TAPE
FIELD NUMBER POSITIONS
133
086
ELEMENT
OCCURRENCE OF SNOW SHOWERS,
SNOW SQUALLS OR SNOW GRAINS
TAPE
CONFIGURATION
0-9
A
*
CODE DEFINITIONS
AND REMARKS
0 » None
1 » Light snow showers
2 = Moderate snow showers
3 " Heavy snow showers
4 - Light snow squall
5 » Moderate snow squall
6 - Heavy snow squall
Beginning Jan 1949 squalls were
reported separately and these
figures should not appear
thereafter.
7 Light snow grains
8 Moderate snow grains
9 Heavy snow grains
A = Unknown
* - Original value invalid
134
087
OCCURRENCE OF SLEET,
SLEET SHOWERS OR HAIL
0-9
A
135
088
OCCURRENCE OF FOG,
BLOWING DUST OR
BLOWING SAND
0-5
A
0 • None
1 - Light sleet or sleet showers
(ice pellets)
2 - Moderate sleet or sleet
showers (ice pellets)
3 • Heavy sleet or sleet showers
(ice pellets)
4 - Light hail
5 - Moderate hail
6 • Heavy hail
7 • Light small hail
8 - Moderate small hail
9 • Heavy small hail
A • Unknown
* - Original value invalid
Prior to April 1970 ice pellets
were coded as sleet
Beginning April 1970 sleet and
small hail were redefined as
ice pellets and are coded as
a 1, 2 or 3 in this position.
Beginning Sep 1956 intensities
of hail were no longer reported
and all occurrences were
recorded as a 5.
0 • None
1 - Fog
2 - Ice fog
3 • Ground fog
4 - Blowing dust
5 " Blowing sand
A » Unknown
* » Original value invalid
These values recorded only when
visibility less than 7 miles.
Oct 1975
43
-------
TAPE DECK
1440
AIRWAYS SURFACE OBSERVATIONS
PAGE NO.
12
TAPE
FIELD NUMBER
136
TAPE
POSITIONS
089
ELEMENT
OCCURRENCE OF SMOKE, HAZE
SMOKE AND HAZE, DUST,
BLOWING SNOW, BLOWING SPRAY
137
090 091
WIND DIRECTION 36 POINTS
TAPE CODE DEFINITIONS
CONFIGURATION AND REMARKS
0-6 0 - None
A 1 • Smoke
* 2 - Haze
3 - Smoke and haze
4 - Dust
5 ™ Blowing snow
6 • Blowing spray
A " Unknown
* » Original value invalid
These values recorded only
when visibility less than 7
miles.
00 - 36 Direction from which the wind
AA is blowing, in tens of degrees.
Stations began using this system
on 01 Jan 1964. To achieve
continuity with earlier records
these values are converted to
the 16 point scale and placed
in field 104.
138
139
092 094
095
BLANK
RECORD MARK
AM
t. A
00 " Calm
AA " Unknown
CONVERSION CODE
tens of 16 pt.
35-01
02-03 -
04-05
06-07
08-10 -
11-12 -
13-14
15-16 -
17-19 -
20-21
22-23 -
24-25 -
26-28 •
29-30
31-32 -
33-34
11
12
22
32
33
34
44
54
55
56
66
76
77
78
88
18
This position may contain a
blank or record mark.
Record mark • 0,2,8, card punch
Oct 1975
44
USCO1U-NOAA-ASHEVI LLE
-------
APPENDIX B
DESCRIPTION OF THE TD-3280 FORMAT
This description is reproduced from documentation provided by the National
Climatic Data Center (NCDC).
45
-------
SURFACE AIRWAYS
HOURLY
TD-3280
Prepared by
National Climatic Data Center
Federal Building
Asheville, North Carolina
March 1986
This document was prepared by the U.S. Department of Commerce, National
Oceanic and Atmospheric Administration, National Environmental Satellite Data
and Information Service, National Climatic Data Center, Asheville, North
Carolina.
This document is designed to provide general information on the content,
origin, format, integrity and the availability of this data file.
Errors found in this document should be brought to the attention of the
Data Base Administrator, NCDC.
46
-------
TABLE OF CONTENTS
INTRODUCTION
HISTORY AND DATA SOURCE Pages 3-4
PURPOSE OF THE MANUAL Page 5
SPECIAL NOTES Pages 5-7
TAPE FORMAT
MANUAL AND TAPE NOTATIONS
1. FILE (NCDC Variable Length Storage Structure)
A. Physical Characteristics Page 8
B. COBOL or FORTRAN Data Descriptions Pages 8-9
(1) Typical ANSI COBOL
(2) Typical FORTRAN 77
C. IBM JCL Notes Page 9
2. RECORD
A. Physical Characteristics Pages 9-10
B. Format (Variable Record) Pages 11-12
v-
RECORD POSITION AND CODE DEFINITIONS Pages 13-33
SAMPLE VARIABLE RECORD Page 34
APPENDIX A
FIXED DATA STRUCTURE Pages 35-39
47
-------
INTRODUCTION
HISTORY AND DATA SOURCE
Weather observations, in support of aircraft operations, have been taken
since the earliest days of aviation. Rapid growth of the industry during the
1940's made it evident that some mechanical means of summarizing the data must
be developed. Adequate statistical information was needed in order to select
appropriate airport sites. Military stations provided most of the early
observations for archiving from 1941 through June 1948. Major changes in
observing and recording practices during 1948 represent the primary basis of
digital information for all the principle reporting stations residing in this
data set.
A major airport study was conducted by the'FAA in the early 1960's. To
facilitate handling large masses of data necessary for this effort, the Weather
Bureau, Air Force, Navy, and the FAA devised common tape formats called Tape
Data Family-14 (TDF-14).
These principle reporting stations are usually fully instrumented and
therefore record a complete range of meteorological parameters. Beginning
January 1, 1965, for most National Weather Service stations and March 1, 1972,
for most Naval Weather Service stations the digitizing of the Airways
Observations was reduced from 24 obs/day to 8 obs/day. These observations, at
3-hourly intervals, coincide with the normal GMT schedule of OOZ, 03Z, 06Z etc.
This means, of course, that the observations, keyed in Local Standard Time
(LST) differ according to time zone. Beginning with August 1981 data, 24
obs/day were again digitized for most active stations.
Through the years approximately 1,380 principle stations have recorded
observations in this program. In 1984 there were just under 300 active
stations being processed for inclusion in the digital data base.
Surface Airways Hourly data were initially transferred to punched cards
beginning in the late 1940's to facilitate summarizing climatological data.
The late 1960's saw the transfer of punched cards to magnetic tape. These
TDF-14 formats represented the digital file through 1983. During 1983 a new
element file structure was developed and processing of airways hourly data was
revised. This new processing system became operational Jan 1984. Data are
currently processed utilizing the new element file structure. The conversion
of historical data included gross data checks on the TD-1440 data file. No
edited values were derived during the historical conversion but undecodable
data were flagged.
Areal coverage includes the U.S., Caribbean Islands, Pacific Islands, and
other overseas stations of the National Weather Service, U.S. Navy, and U.S.
Air Force.
The digital file contains Record Type, Station Identification, Units of
Measurement Indicators, Source Codes, Data Quality Flags, and Element Types:
48
-------
CLOUD DATA; Amount, ceiling height, summation of cloud layer amounts, type of
cloud, and cloud height.
VISIBILITY DATA: Horizontal.
WIND DATA: Speed and direction.
TEMPERATURE DATA; Dry Bulb, Wet Bulb and Dew Point.
SKY COVER DATA; Total Sky, total opaque, and the condition of the sky.
RELATIVE HUMIDITY DATA; Relative humidity.
PRESSURE DATA; Station pressure, sea level pressure, and altimeter.
PRESENT WEATHER DATA; The occurrences of thunderstorms, tornados,
precipitation (Rain, squalls, snow, freezing rain/drizzle, etc.!), fog, blowing
dust, smoke, hail, etc.
Air Force data are available only to the early 1970's. Navy data are
available through current period of record. At the request of the Navy Office,
DATSAV (Global Data Save from U.S. Air Force) telecommunicated data have been
used as the primary source of Navy surface observations since the beginning of
the 1981 data year. These data include 48 Airways stations and 11 Metar
stations. See special notes on DATSAV Source Data.
Due to many special projects performed at NCDC and other Centers, 24
hourly observations may have been keyed for varying periods of time for
selected stations. Inventories must be consulted to determine the exact period
of record for each station.
Beginning with the data for January 1984 the Surface Airways Hourly
observations were processed through a completely revised system. Relying
heavily on new computer editing procedures, data are subjected to internal
consistency checks, compared against climatological limits, checked serially,
and evaluated against surrounding stations.
Quality control "flags" are appended to each element to show how they
fared during the edit procedures and to indicate what, if any, action was
taken. The files then, consist of observed values and, as necessary, an edited
value. Flag 2 must be checked at all times to determine if an edited value is
present.
Source codes were added to this file indicating (1) the primary source of
the original record the element was taken from, and (2) the back-up source of
the original record the element was taken from. The sources include:
(1) Original manuscript; (2) SRRS - Service Record Retention System; (3) AFOS -
Automated Field Operations and Services; (4) DATSAV - Global Data Save from
U.S. Air Force; (5) NMC - National Meteorological Center; (6) Foreign Keyed;
(7) MAPSO - Microcomputer Aided Paperless Surface Observations; (8) SRRS
Manuscript; (9) Other/unknown. Source codes for pre-1984 data were reported as
"original manuscript" only for all stations.
49
-------
PURPOSE OF THE MANUAL
This manual was designed so that reference to other reference material
should be unnecessary. However, additional information may be obtained by
writing or calling:
National Climatic Data Center E/CC42
ATTN: USER Services Branch
Federal Building
Asheville, North Carolina 28801-2696
Telephone inquiries may be directed to:
Commercial 704 259-0682
FTS 672-0682
Read carefully "Manual and Tape Notations," and "Code Definitions and
Remarks" sections.
SPECIAL NOTES
QUALITY
Quality of the Surface Airways Hourly data is considered quite good. All
observations have been subjected to some form of quality control. During the
earlier years this was almost entirely a manual effort. As more sophisticated
techniques of processing were introduced the quality control procedures were
also improved. Today, the quality control effort is a blend of several
computer programs and manual review. Observations are checked for conformance
to established observing and coding practices, for internal consistency, for
serial, or time oriented consistency, and against defined limits for various
meteorological parameters.
TIME
The time entered is that of the record observations, taken within 10
minutes prior to the hour (e.g. 1355 keyed 1400). Prior to Jun 57,
observations were taken within 10 minutes prior to the half hour; minutes are
disregarded in punching (e.g. 0222 punched 02; 1428, 14). All "War Times" and
"Standard Meridian Times" were converted to Local Standard Time before
punching. For Air Force stations in the United States, the times were punched
in accordance with the established time zones. Time entries for Air Force
stations outside the United States were edited prior to punching and where
necessary converted to the Local Standard Time of the nearest meridian evenly
divisible by 15 degrees.
50
-------
CEILING HEIGHT
Ceiling was recorded in hundreds of feet above the ground to nearest 100
feet up to 5,000 feet, to nearest 500 feet from 5,000 to 10,000 feet, to
nearest 1,000 feet above that. Before 1949, Air Force stations recorded
ceilings up to and including 20,000 feet, above which point the ceiling was
classified as unlimited; Weather Bureau and Navy stations recorded ceiling only
up to and including 9,500 feet, above which point the ceiling was considered
unlimited. Beginning in 1949, ceiling was redefined to include the vertical
visibility into obscuring phenomena not classified as thin, that, in summation
with all lower layers, cover 6/10 or more of the sky. Also at that time all
limits to height of ceiling were removed, so that unlimited ceiling became
simply less than 6/10 sky cover, not including thin obscuration. Then,
beginning 1 Jun 51, ceiling heights were no longer established solely on the
basis of coverage. The ascribing of ceilings to thin broken or overcast layers
was eliminated. A layer became classified as "thin" if the ratio of
transparency to total coverage at that level is 1/2 or more.
SKY CONDITIONS AND CLOUD LAYERS
Many different coding practices on sky conditions and cloud layers
occurred throughout the years. The new element format conversion has taken all
the different practices into account and has converted all the procedures into
a common format. If you are interested in all the changes in coding please
refer to WBAN Sfc. Observations Card Deck 144 documentation.
DATSAV SOURCE DATA
Because of differences in Airways and Metar codes and the limited
information available on the telecommunicated source compared with manuscript
forms, DATSAV derived data contains less complete information than otherwise
available. Element conversions unique to Metar stations are as follows:
1. Visibility - Metar codes are converted to Airways codes for the NCDC
data base. This conversion will cause 6 mile visibilities from Metar
stations to be recorded as 7 mile visibilities. METAR code permits
the transmission of a visibility of 9000 meters without obstruction
while Airways requires a visibility of at least 7 miles without
obstruction. The 9000 meters is converted to 6 miles in the program
and flagged because it is less than the 7 mile requirement. These 6
mile visibilities are changed to 7 miles so that these data will
conform with the rest of the data in the data base. When 'CAVOK' is
found in the transmitted data 7 miles with no obstructions is entered
in the data base.
2. Weather - Only the highest numbered weather code is transmitted. This
causes all accompanying weather to be lost from the data base. For
example, the manuscript form might indicate moderate or heavy rain and
snow showers mixed (code 84) with fog (code 45). Only code 84 will be
transmitted and fog will be eliminated.
51
-------
3. Clouds - Total sky and sky condition are not reported on
telecommunication data. Layer amounts are reported in eights and
converted to tenths. This conversion results in.the loss of any
entries of 2 or 7 tenths.
4. Ceiling - When 'CAVOK' is found in the transmitted data an unlimited
ceiling is entered in the data base.
5. Temperature and Dew Point Temperature - These temperatures are given
in Celsius on the forms, Kelvin on DATSAV, Celsius on intermediate
output, and are stored in Fahrenheit in whole degrees in the data
base. Rounding during conversions can cause a loss of accuracy of one
degree.
FILE STRUCTURE
The element file structure is designed to allow maximum flexibility in
requesting data. Only those elements or groups of elements of particular
interest need be ordered. End user input programs can be modified easily to
operate on different sets of elements.
These variable length records contain data as originally reported through
DEC 1983. After that the records contain both the original values and the
edited values.
LOGICAL REFERENCE TO ELEMENT TYPES
(Note: Description of Elements begin on page 13 under
'Code Definition and Remarks')
Logically grouped Element types are as follows:
1. Clouds - CLCx, CLIx, and CLHT.
2. Present Weather - PWTH.
3. Pressure - - PRES, SLVP, and ALTP.
4. Relative Humidity - RHUM.
5. Sky Cover - CC51, C2C3, and TSKC.
6. Temperature - DPTP, TMPD, and TMPW.
7. Visibility - HZVS.
8- Wind - WD16, and WIND.
52
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TAPE FORMAT
MANUAL AND TAPE NOTATIONS
1. FILE (NCDC Variable Length Storage Structure)
A. Physical Characteristics
Data in this file are retained in chronological order by station.
Although library tapes are normally maintained as described below, different
characteristics including fixed length records can be furnished on request.
Additional charges may be accrued for special processing.
B. COBOL or FORTRAN Data Description
(1) Typical ANSI COBOL
FD INDATA
LABEL RECORDS ARE STANDARD
RECORDING MODE D
BLOCK CONTAINS 12000 CHARACTERS
DATA RECORD IS DATA-RECORD.
01 DATA-RECORD.
02 RECORD-TYPE PIC X(3).
02 STATION-ID PICX(8).
02 ELEMENT-TYPE PIC X(4).
02 ELEMENT-UNITS PIC XX.
02 YEAR PIC 9(4).
02 MONTH PIC 99.
02 SOURCE-CODE-1 PIC X.
02 SOURCE-CODE-2 PIC X.
02 DAY PIC 9(2).
02 NUM-VALUES PIC 9(3).
02 DAILY-ENTRY
OCCURS 1 to 100 TIMES DEPENDING ON NUM-VALUES.
04 TIME-OF-VALUE PIC 9(4).
04 DATA-VALUE PIC S9(5) SIGN LEADING SEPARATE.
04 FLAG-1 PIC X.
04 FLAG-2 PIC X.
53
-------
(2) Typical FORTRAN 77
DEFINE FILE 10 (ANSI, VB, 1230, 12000)
CHARACTER*3 RECTYP
CHARACTER*8 STNID
CHARACTER*4 ELMTYP
CHARACTER*2 EUNITS
CHARACTER*4 IYEAR
CHARACTER*2 IMON
CHARACTER*3 NUM
CHARACTER*2 ID AY
CHARACTER*! SCR1, SCR2, FLAG1, FLAG2
DIMENSION ITIME(IOO), IVALUE(IOO), FLAGl(lOO), FLAG2(100)
READ (10,20,END-999) RECTYP, STNID, ELMTYP, EUNITS, IYEAR,
+IMON, SRC1, SRC2, IDAY, NUM, (ITIME(J), IVALUE(J), FLAGl(J),
+FLAG2(J), J-l, NUM)
20 FORMAT (A3, A8, A4, A2, 14, 12, Al, Al, 12, 13, 100 (14, 16,
2 AD)
NOTE: If you do not have FORTRAN 77 you can read the character
data described above into integer variables.
C. IBM JCL NOTES.
1. For ASCII Variable specify;
LRECL » 1234
RECFM =• DB
OPTCODE =• Q
2. For EBCDIC Variable specify:
LRECL = 1234
RECFM » VB
2. RECORD
A. Physical Characteristics
Each logical record contains one station's hourly data values
for a specific meteorological element for a period of one day. The record
consists of a control word, an identification portion, and a data portion. The
control word is used by the computer operating system for record length
determination. The identification portion identifies the record type,
observing station, element type, element units, year/month, source codes, day
and number of values. The data portion contains the meteorological
observations for the hourly data values and flags. The data portion is
repeated for as many hourly values as occur in a day.
NOTE: Present Weather Code (PWTH) is an exception. See Code Definitions
and Remarks on 'PWTH'.
54
-------
NCDC Library Tapes are structured as follows:
Record length
Blocked
Media
Density
Parity
Label
File
Variable with maximum of 1230 characters
12000 characters maximum
ASCII 9 Track
6250 BPI
Odd
ANSI Standard Labeled
1 File per tape
55
-------
B. FORMAT (VARIABLE RECORD)
1. The first ten tape fields, the ID PORTION of the record, describe
the characteristics of the entire record. The DATA PORTION of the record
contains information about each element value reported. This portion is
repeated for as many hourly values as occur in a day.
Each logical record is of variable length with a maximum of 1230
characters. Each logical record contains a station's hourly data for a
specific meteorological element over a one day interval. The form of a record
is:
ID PORTION (30 characters) Fixed length
REG
TYP
XXX
STATION
ID
XXXXXXXX
ELEM
TYPE
XXXX
DNT
XX
YEAR
XXXX
MO
XX
SRC
1
X
SRC
2
X
DAY
XX
NO.
VAL
XXX
TAPE
FIELD
001
002
003 004
005 006 007 008 009 010
DATA PORTION (12 Characters Number-Values Times)
TAPE
FIELD
Oil
TIME
HOUR
XXXX
DATA
ELEM
S
X
VALUE
xxxxx
FL
1
X
FL
2
X
TIME
HOUR
XXXX
DATA
ELEM
S
X
VALUE
XXXXX
4
<
012
013
014 015
016
017
018
>
DATA
ELEM
S
X
VALUE
XXXXX
FL
1
X
FL
2
X
TAPE 198
FIELD
199 200 201
56
-------
TAPE FIELD
001
002
003
004
005
006
007
008
009
010
Oil
012
013
014
015
(016-020)
(021-025)
(026-030)
(196-201)
TAPE
RECORD POSITION
001-003
004-011
012-015
016-017
018-021
022-023
024
025
026-027
028-030
031-034
035
036-040
041
042
( 043-054 )
( 055-066 )
( 067-078 )
(1219-1230)
ELEMENT DESCRIPTION
RECORD TYPE
STATION I.D.
METEOROLOGICAL ELEMENT TYPE
MET. ELEMENT MEASUREMENT UNITS CODE
YEAR
MONTH
SOURCE CODE 1
SOURCE CODE 2
DAY OF MONTH
NUMBER OF DATA PORTION GROUPS THAT FOLLOW
TIME OF OBSERVATION (HOUR)
SIGN OF METEOROLOGICAL VALUE
VALUE OF METEOROLOGICAL ELEMENT
QUALITY CONTROL FLAG 1
QUALITY CONTROL FLAG 2
DATA GROUPS IN THE SAME FORM AS TAPE FIELDS
011-015. REPEATED AS MANY TIMES AS NEEDED
TO CONTAIN ONE DAY OF RECORD.
57
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION -NAME CODE DEFINITIONS AND REMARKS
'001 1-3 Record- The type of data stored in this record. Value is
Type "ELY." Each record contains one day of hourly
• values.
002 4-11 Station- Contains the WBAN Station Number. (Assigned by
ID NCDC.) Range of values - 00000000-00099999. Five
digit station numbers are always right justified
zero filled.
003 12-15 Element- The type of data element stored in this record.
Type Range of values is listed below.
ALT? Altimeter setting. Range of values - 02700
to 03200. (Navy stations only beginning
SEP 1984.)
CC51 The sky condition as recorded prior to June
1951. DATA-VALUE will appear as OXTYZ
where:
X =• Amount of higher layer
YY =• Height of lowest scattered
layer in lOOrds of feet
Z ™ Amount of lowest layer
Note: This element is only recorded for data
prior to June 1, 1951. Check Flags 1 and 2 for
further definition of CC51. C-A-U-T-I-O-N must be
taken when using this element.
Sky condition is a descriptive symbolic coding of
the state of the sky, referring in general to the
amount of the celestial dome covered by clouds or
obscuring phenomena.
X and Z Code Amounts
0 - clear or less than .1 coverage
1 - thin scattered
2 =» scattered
3 » dark scattered
4 - thin broken
5 = broken
6 - dark broken
7 = thin overcast
8 » overcast
9 - dark overcast
- - obscuration 10/10ths obscured
X - (blank) partial obscuration
58
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 YY Code
00 to 95 - Height in hundreds of feet,
96 • Value unknown.
Manuscript entry was 'Jitf'.
97 » No low scattered clouds.
Manuscript entry was ' '.
98 = Invalid original value.
Manuscript entry was '**'.
99 = 10,000 feet or higher.
CLC"x" The sky condition and cloud coverage by
layer where: The "x" in CLCx.
CLC1 » lowest cloud layer
CLC2 - 2nd cloud layer
CLC3 - 3rd cloud layer
CLC4 = 4th cloud layer
CLCN = N'th cloud layer if necessary
s
Cloud information pertaining to sky condition and
cloud coverage are contained within one element
per level. Check data Flags 1 and 2 for further
definition.
The DATA-VALUE portion of the record will appear
as: Example OXXYY constitutes the five character
field where
XX = code for sky condition
YY = cloud coverage (tenths)
XX Code - Sky Condition
00 =• clear or less than .1 coverage
01 = thin scattered .1 to .5 coverage
02 = scattered .1 to .5 coverage
03 = thin broken .6 to .9 coverage
04 * broken .6 to .9 coverage
05 » thin overcast 1.0 coverage
06 • overcast 1.0 coverage
07 » obscuration 1.0 coverage
08 - partial obscuration <1.0 coverage
09 • unknown
YY Code - Cloud Coverage
Cloud coverage is expressed in tenth's.
Value of 9's indicate unknown values.
59
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 CLHT Ceiling height is-defined as the height of
the lowest sky cover layer that is more
than 1/2 opaque. Heights are defined in
hundreds of feet. The DATA-VALUE will
appear as OOXXX. Range of value - 00000 to
00999. Unknown or missing value is 00999.
CLT"x" The cloud type and height by layer where:
The "x" in CLTx.
CLT1 » lowest cloud layer or obscuring
phenomena
CLT2 - 2nd cloud layer
CLT3 - 3rd cloud layer
•
CLTN = N'th cloud layer if necessary
Cloud information pertaining to cloud type
and cloud height are contained within one
element per level. The DATA-VALUE portion
of the record will appear as: example
XXYYY constitutes the five character field
where
XX = Code for cloud type (or obstruction
to vision code at lowest cloud
layer) Code listed on following
page.
YYY = cloud height (hundreds of feet)
9's for any value = unknown
Note: Cloud type/obscuring phenomena code
on following page. Also check Flags
1 and 2 for further definition.
60
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 CLT"x" Generic cloud type or obscuring phenomena
codes are:
CLOUD TYPE
00 » None
11 » Cumulus
12 - Towering Cumulus
13 - Stratus Fractus
14 = Stratus Cumulus Lenticular
15 - Stratus Cumulus
16 » Stratus
17 =• Cumulus Fractus
18 = Cumulonimbus
19 = Cumulonimbus Mammatus
21 - Altostratus
22 = Nimbostratus
23 » Altocumulus
24 = Altocumulus Lenticular
28 « Altocumulus Castellanus
29 = Altocumulus Mammatus
32 = Cirrus
35 = Cirrocumulus Lenticular
37 = Cirrostratus
39 = Cirrocumulus
OBSCURING PHENOMENA
(Began Jan. 1984)
01 = Blowing spray
03 = Smoke and haze
04 = Smoke
05 = Haze
06 = Dust
07 = Blowing dust
30 = Blowing sand
36 = Blowing snow
44 = Ground fog
45 = Fog
48 = Ice fog
50 = Drizzle
60 = Rain
70 = Snow
76 = Ice crystals
98 = Obscuring phenomena other than fog
(prior to 1984)
61
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 C2C3 The total amount of sky covered by the
first two cloud layers and the first three
cloud layers. DATA-VALUE will appear as
OXXYY. where:
XX - Summation of 1st two cloud layers
(lOths)
YY » Svmmation of 1st three cloud layers
(lOths)
Range - 00 to 99.
00 - Clear or < .1
01 - 0.1
02 - 0.2
03 - 0.3
04 - 0.4
05 - 0.5
06 = 0.6
07 - 0.7
08-0.8
09 - 0.9
10 - 1.0
99 » Unknown or missing
NOTE: Check Flags 1 and 2 for further
definition.
DPTP Dew Point Temperature. The DATA-VALUE will
appear as OOXXX. Range of value = 00000 to
00140. 00999 = unknown or missing. (Whole
degrees F.)
62
-------
TAPE
FIELD
TAPE
RECORD
POSITION
ELEMENT
.NAME
CODE DEFINITIONS AND REMARKS
003
HZVS The prevailing "Horizontal Visibility"
(usually at an elevation of 6 feet above
the ground). The DATA-VALUE will appear as
XXXXX. Range of value = 00000 to 99999.
9's indicate unknown or missing values.
(100th's of miles.) Code follows on next
page.
HZVS CODE
00000 => Zero vsby
00006 =1/16 mile
00012 = 1/8
00019 - 3/16
00025 - 1/4
00031 =• 5/16
00038 = 3/8
00050 = 1/2
00062 = 5/8
00075 - 3/4
*00081 = 3/4 or 7/8
00087 - 7/8
00100 = 1 mile
00112 - 1 1/8
00125 = 1 1/4
00138
00150
00162
00175
00200
00225
00250
00275
00300
00400
etc!
01000
10000
99999
- 1 3/8
= 1 1/2
- 1 5/8
= 1 3/4
= 2 miles
= 2 1/4
- 2 1/2
- 2 3/4
= 3
= 4
= 10
= 100
= Missing
Unknown or
Unlimited
(See Flag 1)
Note: Historical archived data prior to
Jan. 1984 did not differentiate between 3/4
and 7/8 visibilities. This ambiguous
TD-1440 Historic Data was converted to
TD-3280 as '00081' .
PRES The station pressure at station level in
inches and thousandths of mercury
generally. The DATA-VALUE will appear as
XXXXX. Range of value = 19000 to 39990.
99999 = unknown or missing.
63
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 PWTH The present (or prevailing) weather
occurring at the time of the observation.
DATA-VALUE will appear as follows:
PRESENT WEATHER CODES
Present weather codes are two characters in
length. The leftmost character indicates
the general class of present weather while
the rightmost character is a qualifier.
The two digit codes are stored into the
five digits of the DATA-VALUE portion.
***If there is no occurrence of present
weather the valid DATA-VALUE will always be
00000. Within the five digits used, the
leftmost digit is always set to zero. The
two-digit weather codes are entered left
justified for the remaining four digits.
Thus, if one type of weather occurs during
an hour the code would appear as OXXOO,
where XX is the appropriate code. If two
types of weather occur for the same hour,
the value field would appear as OXXYY.
If more than two types occur for the same
hour they will be stored into additional
PWTH records as necessary.
Consider the following examples:
On day 11 Feb 1981 at 12 noon and 1300
hours no present weather occurred.
0054HLY00005264PWTHNA1981021111002120Qif
OOOOQi511300bOOOOO#l
64
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 On day 11 Feb 1981 at 12 noon light snow,
light freezing rain, ice fog, and blowing
snow all occur. The records will appear
as:
0042HLY000005264PWTHNA19810211110011200
0402631
0042HLY000052664PWTHNA19810211110011200
07184,151
Note: PWTH DATA-VALUE codes are described
on pages 20 thru 25.
CODE FOR PWTH RANGE 00.
00 ********** No Occurrence
where:
00 «• No present weather occurred
CODE FOR PWTH RANGE 10 TO 19.
IX ********** Thunderstorm, Tornado,
Squall
where:
X « 0 thunderstorm - lightning and thunder.
Wind gust < 50 knots - hail < .75 in.
= 1 heavy or severe thunderstorm -
frequent intense lightning and
thunder. Wind gust > 50 knots - hail
> .75 in.
= 2 report of tornado or water spout
- 3 light squall (through May 1951 only)
= 4 moderate squall
Moderate squall is recorded. Squall
is sudden increase of wind speed by
at least 16 knots, reaching 22 knots
or more and lasting for at least one
minute.
= 5 heavy squall (through May 1951 only)
=• 6 water spout (began Jan 1984)
- 7 funnel cloud (began Jan 1984)
= 8 tornado (began Jan 1984)
» 9 unknown
65
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION- NAME CODE DEFINITIONS AND REMARKS
CODE FOR PWTH RANGE 20 TO 29
2x ********* Rain, Rain Showers, Freezing
Rain
where:
X - 0 light Rain
» 1 moderate Rain
• 2 heavy Rain
- 3 light Rain showers
" 4 moderate Rain showers
=• 5 heavy Rain showers
= 6 light freezing Rain
* 7 moderate freezing Rain
» 8 heavy freezing Rain
= 9 Unknown
Light =• Trace « .005 in.) to .10 inches
per hour
Moderate =» .11 to .30 inches per hour
Heavy =• > .30 inches per hour
66
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 CODE FOR PWTH RANGE 30 TO 39
3X ********* Rain Squalls, Drizzle,
Freezing Drizzle
where:
X = 0 light rain squalls
= 1 moderate rain squalls
= 2 heavy rain squalls (through 1948
only)
= 3 light drizzle
= 4 moderate drizzle
= 5 heavy drizzle
= 6 light freezing drizzle
= 7 moderate freezing drizzle
= 8 heavy freezing drizzle
= 9 unknown
When drizzle or freezing drizzle occurs
with other weather phenomena:
Light = Trace « .005 in.) to .01 inches
per hour
Moderate = > .01 to .02 inches per hour
Heavy = > .02 inches per hour
When drizzle or freezing drizzle occurs
alone:
Light = Visibility 5/8 mile or greater
Moderate = Visibility 5/16 - 1/2 mile
Heavy = Visibility 1/4 mile or less
67
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 CODE. FOR PWTH RANGE 40 TO 49
4X ********* Snow, Snow Pellets, Ice
Crystals
where:
X - 0 light snow
» 1 moderate snow
» 2 heavy snow
» 3 light snow pellets
™ 4 moderate snow pellets
» 5 heavy snow pellets
• 6 light ice crystals
» 7 moderate ice crystals
» 8 heavy ice crystals
= 9 unknown
Beginning April 1963 any occurrence of ice
crystals is recorded as a 47. Prior to
this date intensities were reported.
CODE FOR PWTH RANGE 50 TO 59
5X ********* Snow Showers, Snow Squalls,
Snow Grains
where:
X = 0 light snow showers
= 1 moderate snow showers
=* 2 heavy snow showers
= 3 light snow squall
= 4 moderate snow squall
= 5 heavy snow squall
Beginning Jan 1949 squalls were reported
separately and these figures below should
not appear thereafter.
** 6 light snow grains
= 7 moderate snow grains
= 8 heavy snow grains
= 9 unknown
68
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 CODE FOR PWTH RANGE 60 TO 69
6x ********* Sleet, Sleet Showers, Hail
where:
X ** 0 light ice pellet showers
» 1 moderate ice pellet showers
= 2 heavy ice pellet showers
- 3 light hail
= 4 moderate hail
= 5 heavy hail
= 6 light small hail
= 7 moderate small hail
= 8 heavy small hail
= 9 unknown
Prior to April 1970 ice pellets were coded
as sleet. Beginning April 1970 sleet and
small hail were redefined as ice pellets
and are coded as 60, 61, or 62. Beginning
Sep 1956 intensities of hail were no longer
reported and all occurrences were recorded
as a 64.
CODE FOR PWTH RANGE 70 to 79
7X ********* Fog, Blowing Dust, Blowing
Sand
where:
X = 0 fog
= 1 ice fog
= 2 ground fog
= 3 blowing dust
= 4 blowing sand
= 5 heavy fog
= 6 glaze (begin 1984)
= 7 heavy ice fog (begin 1984)
= 8 heavy ground fog (begin 1984)
= 9 unknown
These values recorded only when visibility
less than 7 miles.
69
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 CODE FOR PWTH RANGE 80 TO 89
gx ********* Smoke, Haze, Smoke and Haze,
Blowing Snow, Blowing Spray,
Dust
where:
X - 0 smoke
» 1 haze
- 2 smoke and haze
- 3 dust
= 4 blowing snow
- 5 blowing spray
- 6 dust storm (begin 1984)
= 9 unknown
These values recorded only when visibility
less than 7 miles.
CODE FOR PWTH RANGE 90 TO 92 AND 99
9X ********* ice Pellets
where:
X =• 0 light ice pellets
=• 1 moderate ice pellets
= 2 heavy ice pellets
= 9 Unknown
RHUM Relative Humidity expressed in whole
percent. The DATA-VALUE will appear as
OOXXX. Range of value - 00000 to 00100.
00999 indicates unknown or missing values.
SLVP Pressure, reduced to sea level, expressed
in millibars and tenths. The DATA-VALUE
will appear as XXXXX. Range of value »
09000 to 10999. 99999 indicates unknown or
missing values.
70
-------
TAPE
FIELD
TAPE
RECORD
POSITION
ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
003
TMPD Dry Bulb (Air) Temperature. The specified
temperature in whole degrees Fahrenheit.
The DATA-VALUE will appear as OOXXX. Range
of value = 00000-00140. 00999 = unknown or
missing.
TMPW Wet Bulb Temperature expressed in degrees
Fahrenheit to tenths. The DATA-VALUE will
appear as OXXXX. Range of value 00000 to
01400. 00999 = unknown or missing.
TSKC Total sky cover and total opaque sky cover.
Range of value 00 to 10 (tenths) and 99.
The amount of the celestial dome covered by
clouds or obscuring phenomena. Opaque
means clouds or obscuration through which
the sky or higher cloud layers cannot be
seen.
The DATA-VALUE will appear as OXXYY where
XX is the total sky cover and Tf is the
total opaque sky cover.
00 = clear or less than .1 coverage
01 = scattered clouds .1 coverage
02 = scattered clouds .2 coverage
03 « scattered clouds .3 coverage
04 = scattered clouds .4 coverage
05 = scattered clouds .5 coverage
06 = broken clouds .6 coverage
07 = broken clouds .7 coverage
08 = broken clouds .8 coverage
09 = broken clouds .9 coverage
10 = overcast 1.0 coverage
99 = unknown
71
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 WD16 Wind direction and speed to 16 point WBAN
code. Direction is the direction from
which the wind is blowing. Speed in knots.
WIND DIRECTION CODES
(through Dec. 1963 only)
16 Pt
WBAN Code Degrees
00 » Calm Calm
11 - N 349-011
12 = NNE 012-033
22 = NE 034-056
32 - ENE 057-078
33 - E 079-101
34 » ESE 102-123
44 - SE 124-146
54 - SSE 147-168
55 =» S 169-191
56 =• SSW 192-213
66 - SW 214-236
76 - WSW 237-258
77 = W 259-281
78 = WNW 282-303
88 - NW 304-326
18 - NNW 327-348
Example of DATA-VALUE XXYYY for wind
direction and speeds: 12037 Wind is from
the NNE at 37 knots. 12 » Wind from NNE.
037 = Wind speed is 37 knots.
NOTE: Beginning 1 Jan 1964 wind directions
were observed and coded to tens of
degrees. WD16 code no longer
reported.
72
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TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
003 WIND Wind Direction and Speed. Direction is the
direction from which the wind is blowing.
Speed in knots. Range of value (direction)
= 00 to 36 and 99. Range of value (speed)
= 000 to 250.
Example of DATA-VALUE XXYYY for wind
direction and speeds: 02037 Wind is from
020 degrees at 37 knots. 02 = Wind 020
degrees. 037 = Wind speed is 37 knots.
NOTE: WIND (10's of Degrees Code) element
begins January 1964. Prior to 1964
winds observed in the WD16 (16 point
code).
WIND DIRECTION CODES
(begin 1964)
10s of
Degrees Code Degrees
00 = Calm
01 = 010
02 = 020
through
36 = 360
99 = Unknown
73
-------
TAPE
FIELD
TAPE
RECORD
POSITION.
ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
004 16-17 ELEMENT- The units and decimal position of the DATA-VALUE
UNITS for this record.
ELEMENT-UNITS TABLE
DT Wind direction in tens of degrees
F Whole degrees Fahrenheit
HF Hundreds of feet
HM Miles and hundredths
IH Inches and hundredths of mercury
IT Inches and thousandths of mercury
KD Knots and direction in tens of degrees
KS Knots and direction in 16 point WBAN Code
MT Millibars and tenths
NA No units applicable (non-dimensional)
Nl No units applicable - element to tenths
N2 No units applicable - element to hundredths
P Whole percent
TF Degrees Fahrenheit in tenths
NOTE: Single digits are left justified blank
filled.
005
18-21
YEAR
This is the year of the record.
1900-current year processed.
Range of value is
006
22-23
MONTH
This is the month of the record.
is 01-12.
Range of value
74
-------
TAPE
TAPE RECORD ELEMENT
FIELD POSITION NAME CODE DEFINITIONS AND REMARKS
007 24 SOURCE Contains a code indicating the primary
CODE-1 source of the original record this element was
taken from. Range is 1-9.
SOURCE CODE TABLE
1 Original manuscript
2 SRRS
3 AFOS
4 DATSAV
5 NMC
6 Foreign keyed
7 MAPSO-
8 SRRS plus
9 Other/unknown
Source codes reflect normally expected data
sources and do not necessarily indicate the actual
source of a specific item. Pre-1984 data will
only contain a 1.
008 25 SOURCE Contains a code indicating the back-up
CODE-2 source of the original record this element was
taken from. Range is 1-9.
SOURCE CODE TABLE
1 Original manuscript
2 SRRS
3 AFOS
4 DATSAV
5 NMC
6 Foreign keyed
7 MAPSO
8 SRRS plus
9 Other/unknown
Pre-1984 data will only contain a 1.
009 26-27 DAY Contains the day of the record. Range is 01-31.
75
-------
TAPE
FIELD
TAPE
RECORD
POSITION
ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
010
28-30
NUM-
VALUES
This notates the actual number of values reported.
Range of values is 001-048.
NOTE: A record may contain fewer or more data
values than you might expect. A daily record of
hourly values may contain as few as 1 data value
or as many as 48. This is primarily due to
missing or edited data. If a particular data
value was not taken or is unavailable there is no
entry for it. Also, when erroneous data are
encountered during quality control the original
values are flagged and are followed by replacement
values (see FLAG-2 TABLE for details).
Oil 31-34 TIME-OF- Contains the hour and minute of the
.VALUE hourly element value. Range is 0000-2300. The
hour is.in the leftmost two digits and the minute
is in the rightmost two digits. Hour is reported
using the 24 hour clock. (Minutes are always 00.)
See 'Special Notes' on time of record
observations.
012
35
SIGN OF
METEOR-
OLOGICAL
VALUE
This is the 'SIGN' of the meteorological data
value (Tape Field 013). This field contains
either a blank or a minus sign (never a plus
sign).
013
36-40
DATA-
VALUE
Actual data value. This field is a five digit
integer. Units and decimal position are indicated
in the ELEMENT-UNITS field described in Tape Field
004.
76
-------
TAPE
FIELD
TAPE
RECORD
POSITION
ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
014
41
FLAG-1
The data measurement FLAG.
FLAG-1 TABLE (Measurement Value)
C Ceiling of cirroform clouds at unknown height
(Sept 56 - Mar 70)
D Derived value
R Dew Point and/or Relative Humidity, originally
calculated with respect to ice have been
recomputed with respect to water. (DPTP,RHUM)
U Unlimited ceiling height (DATA-VALUE = 99999).
(CLHT)
)S (blank) Flag not needed. (All elements except
CC51)
The following 4 flags apply only to the 'CC511
element type produced for cloud coverage prior to
July 1951. .
B The 0 found in byte 2 should be a '#' = Thin
obscuration
* The 0 found in byte 2 should be a '*' =
Original value invalid
- The 0 found in byte 2 should be a '-' = Total
obscuration.
9 The digit found in byte 2 (high cloud amount)
is a valid code. See Pre-6/51 Cloud Cover
Table.
77
-------
TAPE
FIELD
TAPE
RECORD
POSITION.
'ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
015
42
FLAG-2
The data.quality FLAG.
FLAG-2 (Quality Flag)
(Valid for all elements except CC51)
0 Observed data has passed all internal
consistency checks
1 Validity indeterminable (primarily for pre-1984
data)
2 Observed data has failed an internal
consistency check - subsequent edited value
follows observed value
3 Data beginning 1 JAN 84 - Observed data has
failed a consistency check - No edited value
follows.
Data prior to 1 JAN 84 - Observed data exceeded
preselected climatological limits during
conversion from historic TD-1440 files. No
edited value follows.
4 Observed data value invalid - no edited value
follows
5 Data converted from historic TD-1440 exceeded
known climatological extremes - no edited value
follows
E Edited data value passes all system checks - no
observed value present
M Manually edited data value added to data set
after original archival. Automated edit not
performed on this item.
S Manually edited data passes all systems checks
The following 4 flags apply only to the 'CC51'
element type produced for cloud coverage prior to
June 1951.
B The 0 found in byte 5 should be a 'b' - Thin
obscuration
- The 0 found in byte 5 should be a '-' - Total
obscuration
* The 0 found in byte 5 should be a '*' -
Original value invalid
9 The digit found in byte 5 (low cloud amount) is
a valid code. See Pre-6/51 Cloud Cover Table
for Element 'CC51'.
78
-------
SAMPLE VARIABLE RECORD
(As seen from tape dump)
NOTE: ]6
(column
scale)
Blank Space
123456
123456789012345678901234567890123456789012345678901234567890
(data) 0058HLY00034564TMPDF^19840241100021200J50001ZK11800-00005^1
DUMP RECORD
POSITION POSITION CONTENTS MEANING
1-4
5-7
8-15
16-19
20-21
22-25
26-27.
28
29
30-31
32-34
35-38
39
40-44
45
46
47-50
51
52-56
57
58
In this
1-3
4-11
12-15
16-17
18-21
22-23
24
25
26-27
28-30
31-34
35
36-40
41
42
43-46
47
48-52
53
54
HLY
00034
TMPD
F#
1984
02
4
1
10
002
1200
»
00012
*
1
1800
-
00005
X
1
case, values for
0058 Record control word used by the operating system.
(Contains the total number of characters in the
record - not available to user programs)
RECORD-TYPE
00034564 STATION-ID (WBAN station number)
ELEMENT-TYPE
ELEMENT-UNITS (Left justified blank filled)
YEAR
MONTH
SOURCE-CODE-1 (Primary source = DATSAV)
SOURCE-CODE-2 (Back-up source = Manuscript)
DAY OF THE MONTH
NUM-VALUES; Two data entries follow
TIME-OF-VALUE (HOUR 12, MINUTE 00)
SIGN OF METEOROLOGICAL VALUE
DATA-VALUE
FLAG-1
FLAG-2
FIRST
1— DATA
ENTRY
TIME-OF-VALUE (HOUR 18, MINUTE 00)
SIGN OF METEOROLOGICAL VALUE
DATA-VALUE
FLAG-1
FLAG-2
SECOND
— DATA
ENTRY
case, values for hours 00-11, 13-17, and l°-23 are missing.
-------
APPENDIX A
FIXED DATA STRUCTURE (TD-3280) .
Definitions and general information about the Surface Airways Hourly
observations are-contained in the basic documentation used to describe the format
of variable length records.
MANUAL AND TAPE NOTATIONS
1. FILE (NCDC Fixed Length (User Services))
A. Physical Characteristics
Data in this file are retained in chronological order by station.
The fixed length records described below can be furnished upon request.
Additional charges may be accrued for this special processing.
B. COBOL or FORTRAN Data Description
(1) Typical ANSI COBOL
FD INDATA
LABEL RECORDS ARE STANDARD (FOR STD LABEL TAPES)
RECORDING MODE F
BLOCK CONTAINS 12000 CHARACTERS
DATA RECORD IS DATA-RECORD.
01 DATA-RECORD.
02 RECORD-TYPE PIC X(3).
02 STATION-ID PIC X(8).
02 ELEMENT-TYPE PIC X(4).
02 ELEMENT-UNITS PIC XX.
02 YEAR PIC 9(4).
02 MONTH PIC 99.
02 SOURCE-CODE-1 PIC X.
02 SOURCE-CODE-2 PIC X.
02 DAY PIC 9(2).
02 NUM-VALUES PIC 9(3).
02 DAILY-ENTRY
OCCURS 24 TIMES.
04 TIME-OF-VALUE PIC 9(4).
04 DATA-VALUE PIC S9(5) SIGN LEADING SEPARATE.
04 FLAG-1 PIC X.
04 FLAG-2 PIC X.
80
-------
(2) Typical FORTRAN 77
DEFINE FILE 10 (ANSI, VB, 318, 6360)
CHARACTER*3 RECTYP
CHARACTER*8 STNID
CHARACTER*4 ELMTYP
CHARACTER*2 EUNITS
CHARACTER*! SCR1, SCR2, FLAG1, FLAG2
DIMENSION ITIMEC24), IVALUE(24), FLAG1(24), FLAG2(24)
READ (10,20,END=999) RECTYP, STNID, ELMTYP, EUNITS, IYEAR,
+IMON, SRC1, SCR2, IDAY, NUM, (ITIME(J), IVALUE(J), FLAGl(J),
+FLAG2(J), J-l, 24)
20 FORMAT (A3, A8, A4, A2, 14, 12, Al, Al, 12,.13, 100 (14,
16, 2A1))
NOTE: If you do not have FORTRAN 77 you can "read the
character data described above into integer
variables.
1. RECORD
A. Physical Characteristics
Each logical record contains one station's hourly data values for a
specific meteorological element for a period of one day. The record consists of
an identification portion, and a data portion. The identification portion
identifies the record type, observing station, element type, element units,
year/month, source codes, day, and number of values. The data portion contains
the meteorological observations for the hourly data values and quality flags. The
data portion is repeated 24 times.
NOTE: Present Weather Code (PWTH) is an exception. See Code Definitions and
Remarks on 'PWTH' in documentation on variable format.
NCDC Library Tapes are structured as follows:
Record length
Blocked
Media
Density
Parity
Label
File
FIXED 318 characters
6360 characters
ASCII or EBCDIC Modes - 9 Track
800, 1600, or 6250 BPI
Odd
ANSI standard labeled (ASCII only) or unlabeled
1 File per tape
These fixed length records may be selected in either of the following two
forms:
1. The data values as originally reported.
2. The data values as originally reported with edited replacement
values substituted for the values which did not pass the quality
checks.
If no choice is made by the User, NCDC will supply form //2.
81
-------
B. FORMAT (FIXED RECORD)
1. The first ten tape fields, the ID PORTION of the record,
describe the characteristics of the entire record. The DATA PORTION of the record
contains information about each element value reported. This portion is repeated
for 24 hourly values representing 1 full day of observations.
Each logical record is of fixed length with 318 characters. Each logical
record contains a station's data for a specific meteorological element over a one
day interval. The form of a record is:
ID PORTION (30 characters) Fixed length
TAPE
FIELD
REG
TYP
XXX
STATION
ID
JUUULXXXX
ELEM
TYPE
xxxx
UNT
XX
YEAR
XXXX
MO
XX
SRC
1
X
SRC
2
X
DAY
XX
NO.
VAL
XXX
001
002
003 004
005 006
007 008
009 010
DATA PORTION (12 Character Data Portion repeats the number of times
indicated by the data value stored in Tape Field 010,
Fixed are 12 characters repeated 24 times.)
TAPE
FIELD
TIME
HOUR
XXXX
DATA
ELEM
S
X
VALUE
xxxxx
FL
1
X
FL
2
X
TIME
HOUR
XXXX
DATA
. ELEM
S
X
VALUE
XXXXX
<
Oil 012 013 014 015
016
017 018
TAPE
FIELD
>
>
DATA
ELEM
S
X
VALUE
XXXXX
FL
1
X
FL
2
X
127 128 129 130
82
-------
SAMPLE FIXED RECORD
(As seen from tape dump)
NOTE: X> - Blank Space
(column 123456
scale) 123456789012345678901234567890123456789012345678901234567890
(data) HLY00001102TMPDE81981011101024010CW500012KX0200-99999M)J
RECORD
POSITION CONTENTS MEANING
1-3
4-11
12-15
16-17
18-21
22-23
24
25
26-27
28-30
31-34
35
36-40
41
42
43-46
47
48-52
53
54
ELY
00001102
TMPD
F#
1981
01
1
1
01
024
0100
(BLANK)
00012
(BLANK)
(BLANK)
0200
-
99999
M
(BLANK)
RECORD-TYPE.
STATION-ID 01102 (WBAN Station Number).
ELEMENT-TYPE.
ELEMENT-UNITS. (Left justified blank filled)
YEAR.
MONTH.
SOURCE CODE 1. (Manuscript)
SOURCE CODE 2. (Manuscript)
DAY OF MONTH.
NUM-VALUES: 24 data entries follow.
TIME-OF-VALUE (0100 Hour)
SIGN OF METEOROLOGICAL VALUE
DATA-VALUE
FLAG-1
FLAG- 2
TIME-OF-VALUE (0200 Hour)
SIGN OF METEOROLOGICAL VALUE
DATA-VALUE
FLAG-1
FLAG- 2
FIRST
— DATA
ENTRY
SECOND
-DATA
ENTRY
(55-318 contains repeats for hourly values 3 thru 24.)
83
-------
TAPE
TAPE FIELD RECORD POSITION ELEMENT DESCRIPTION
001 001-003 RECORD TYPE
002 004-011 STATION I.D.
003 012-015 METEOROLOGICAL ELEMENT TYPE
004 016-017 MET. ELEMENT MEASUREMENT UNITS
005 018-021 YEAR
006 022-023 MONTH
007 024 SOURCE CODE 1
008 025 SOURCE CODE 2
009 026-027 DAY OF MONTH ;
010 028-030 NUMBER OF DATA PORTION GROUPS THAT FOLLOW (24)
Oil 031-034 TIME OF OBSERVATION (HOUR - LEFT JUSTIFIED)
012 035 SIGN OF METEOROLOGICAL VALUE
013 036-040 VALUE OF METEOROLOGICAL ELEMENT
014 041 QUALITY CONTROL FLAG 1
015 042 QUALITY CONTROL FLAG 2
(016-020) ( 043-054 ) DATA GROUPS IN THE SAME FORM AS TAPE FIELDS
(021-025) ( 055-066 ) 011-015.
(026-030) ( 067-078 ) REPEATED 24 TIMES.
(126-130) ( 307-318)
84
-------
APPENDIX C
DESCRIPTION OF THE TD-5600 FORMAT
This description is reproduced from documentation provided by the National
Climatic Data Center (NCDC).
85
-------
NAME:
TIME PERIOD:
GEOGRAPHIC COVERAGE:
FORMAT:
FILE SIZE:
FILE STRUCTURE:
CONTENTS:
UPPER AIR (RAWINSONDE) OBSERVATIONS (TD-5600).
1952 (some as early as November 1945) through present
(updated monthly).
United States stations and U.S. controlled stations,
Global.
IBM EBCDIC variable length records with no more than
6000 characters per block are on NCDC's library reels
of magnetic tape which can be copied. NCDC cannot copy
variable length to ASCII mode. A standard record
length format is available, however, in either ASCII or
EBCDIC modes. In the fixed format, blanks are filled
in following the last reporting level making each
observation (record) 2000 characters in length.
232 magnetic tapes;
EBCDIC mode.
9-track, odd parity, 1600 bpi,
This file was produced from rawinsonde observations
recorded on WBAN 31's and digital computer output for
Automatic Raob stations. The file record allows for up
to 89 levels, including the surface level. The surface
level is always first and follows 25 positions of
identification. Standard and significant levels follow
the surface level in descending pressure (ascending
height) order. The data are sorted on tape by station
(WBAN number) in sets; beginning of record-June 1970,
July 1970-December 1976, January 1977-December 1980,
1981, and 1982, and monthly thereafter. The data are
also sorted by time for the beginning of record through
June 1970 and 1977, 1978, and 1979. These magnetic
tapes are available for purchase from the NCDC.
The major parameters that make up this file are
observation time (year, month, day, hour), number of
levels, pressure of level (MB to lOths), height of
level (geopotential meters), temperature of level (Deg
C to lOths), relative humidity of level (%), and wind
direction (whole degrees) and wind speed (meters per
second) of level.
86
-------
S DECS
TDF-56 VAR AND STN
TAPE FORMAT DOCUMENTATION
RAWTNSONDE OBSERVATIONS
PAGS NO,
VARIABLE1
TAPE
POSITIONS
39-43
44-46
47-49
50-52
53-55
56
57
53
STANDARD
31-33
36-38
39-41
42-44
45-47
48
49
50
Heighc of the level, above sea level, in geopoeenci.il
meters.
Signed plus » HGT above sea level
•Signed minus » HCT below sea level
In laeer years Che positive HGT may or may noe be signed.
TEMPERATURE Temperature of the level in degrees celsiu* and tenths.
Signed plus • Positive temp
*Signed minus " Negative tamp
la Later years the positive Temp may or may not be signed.
RELATIVE HUMIDITY Relative humidity of the level in whole percent.
Signed plus - Actual SH
•Signed minus » Estimated RH
In lacer years the actual RH nay or nay not be signed.
WIND DIRECTION
WIND SPEED
BLANK
BLANK
LEVEL TYPE
INDICATOR
Hind direction of the leveL in whole degrees.
Wind speed of the level in meters per second.
BLANK • Blank
1 - S?C Level
2 • First Tropopauae Level
4 • Mandatory or S{g. Level
3 " Generated Level
0 - All Others
Each data level is 25 bytes. Hissing data fields are coded as all 9's (with signed fields being signed minus in
recent years). The firsc level is always the surface level. All other levels then follow in decreasing
pressure or ascending heighc order.
Variable - Observations are packed as many as possible into variable length blocks that do not exceed 6000
bytes.
Standard - Format allows for up to 79 levels, including the surface level of 25 positions each. Blanks are
filled in following the last reported level making each observations 2000 character positions in
length.
If observations contain more than 79 levels, the observations would continue in the next record and
th* number of levels (tape position 13-19) would b« coded 90-99, i.e., 90 and 91 " level 30 and 31,
etc.
*Kight most position of these fields may contain the characters A-I •• Positive 1 through 9 and J-R • Negative
I through 9. A positive or negative 0 in this position may appear as a special character or a non-printable
character.
87
-------
TAPE FORMAT DOCUMENTATION
TAP?
TDF-56 VAR AND STN
SATOJSONDE OBSERVATIONS
E SO.
BLC
LGTH
OBS
LCTH
xxxx
DECK
HO.
56XX
STK
NO.
XXXXX
oas. TIME
YR MO DT HE
XX XX XX XX
NO.
LVL
XX
BLANK
OR
SHIP
POS.
XXXXXX
PRESS
SURFACE (l3t LIVED
HOT
xxxxx
IMP
XXX
RH
XXX
WND
DIR
XXX
UND
SPD
XXX
HIGHEST (LAST LEVEL)
PRESS
XHJLJ
HGT
XXXXX
TUP
XXX
33.
XXX
WND
DIR
XXX
WHO
SPD
XXX
a
T
I
X
T
I
X
B
L
K
X
OBS
LCTH
AJwU.
DECK
NO.
56XX
STN
NO.
OR
LAT.
xxxxx
OBS. TIME
YS
XX
MO
XX
DY
XX
£&
XX
VARIABLE
TAPE
POSITIONS
05-08
09-12
13-17
18-19
20-21
22-23
2'+-2 5
26-27
28-33
STANDARD
01-04
05-09
10-11
12-13
14-15
16-17
13-19
20-25
ELEMENT
BLOCK. LENGTH
Number of bytes in this physical record - in binary. This
occurs once each block..
OBSERVATION LENGTH Number of bytes in this logical record - in binary. This
field occurs at the beginning of each observation.
Unique for each type or source of data.
VBAN number or ihip number
78 " 1978 etc.
01 - 12 • Jan.-Dec.
01-31 " Day of month
00 - 23 • GMT
Number of 25 character levels contained in this observation.
Blank for land stations
DEO:
STATION NUMBER
YEAR
MONTH
DAY
HOUR
MEMBER Or LEVELS
BLANK OR
SHIP POSITION
34-38
26-30
PRESSURE
9 » Indicator
o » Octane of the globe
LjLa » Hhola degrees of Utitutde
LgLg • Units and tens digits of longitude
If octane » 1, 2, (t or 7, add one hundred Co 1^
Pressure of the level in millibars and tenths.
-------
APPENDIX D
DESCRIPTION OF THE TD-6200 FORMAT
This description is reproduced from documentation provided by the National
Climatic Data Center (NCDC).
89
-------
NCDC UPPER AIR
DIGITAL FILES
TD-6200 SERIES
Prepared by
National Climatic Data Center
Federal Building
Asheville, North Carolina
May 1986
This document was prepared by the U.S. Department of Commerce, National
Oceanic and Atmospheric Administration, National Environmental Satellite Data
and Information Service, National Climatic Data Center, Asheville, North
Carolina.
This document is designed to provide general information on the content,
origin, format, integrity and the availability of this data file.
Errors found in this document should be brought to the attention of the
Data Base Administrator, NCDC.
90
-------
INTRODUCTION
SOURCE
The Upper Air Observations in this digital data file include stations
operated by the National Weather Service, U.S. Navy, and certain South American
stations whose data receive quality control at the National Climatic Data
Center (NCDC). Additional Upper Air Observations from the Global
Tele-Communications System (GTS), and the U»S. Air F.orce are also included in
this digital file but are not quality controlled by NCDC.
A list of these files are:
TD-6201 U.S. Rawinsortde observations 1946-Present.
(Includes U.S. Navy observations, U.S. Air Force,
National Meteorological Center (NMC), and South
American cooperative observations. Derived from
TD-5600.)
TD-6202 Northern Hemisphere GTS observations 1963-1970, and
Southern Hemisphere 1966-1970. (These data were
extracted from NMC Operations Archive and processed
into TD-5683.)'
TD-6203 Global GTS observations 1971-1979.
(These data are a composite of NOAA's National
Meteorological Center (NMC) and U.S. Air Force Global
Weather Center (GWC). Derived from TD-5681.
91
-------
Background Information TD-6201
TD-6201: PERIOD:
National Weather Service Jan. 1946 - Current
U.S. Air Force Jan. 1946 - Dec. 1970
U.S. Navy July 1949 - Current
The information contained in TD-6201 includes pressure surface, height of
the pressure surface, temperature, relative humidity, wind direction and speed.
Beginning with Jan 1981, the elapsed time since release of the sonde is
included. The pressure levels included fall into three categories:
1. Mandatory levels — Levels required by the WHO for transmission in
parts A and C of a coded RAW1ND report.
2. Standard levels — Levels used for internal processing by the NCDC,
but not generally reported in a coded message.
3. Significant levels — Levels required to adequately describe a
sounding, as transmitted in parts B and D of a coded message.
The number of mandatory and standard levels has increased over time.
Table 1 lists the levels that are expected for a given period of record.
Significant levels were not generally included in the earlier periods.
Significant levels are included for most stations only after Jul-y 1952.
Levels below the surface were generated for the period January 1, 1981
through February 28, 1986. However, these levels only contain unknown values
('9999') for all data elements. Beginning March 1, 1986 this practice was
stopped.
The actual time of releases from Jan. 1946 through May 1957 were usually
03, 09, 15, 21 GMT, 16, 17 = 15Z and 20, 21, 22, 23 = 21Z. Beginning June 1957
the scheduled time of release is used instead of the actual hour. The time of
observations were changed from 03, 09, 15, 21 GMT to 00, 06, 12, and 18 GMT.
Observations outside the plus or minus one-hour tolerance were reported as
actual time, GMT. Stations scheduled to record only one observation daily are
allowed a six-hour tolerance.
Relative humidities were computed with respect to ice from Jan. 1946
through Sept. 1948 and to water after that. Beginning Oct. 1948 relative
humidity was computed over a water surface whenever the dry bulb was below
freezing.
Observing practice for wind measurements varied from current practice.
from Jan. 1946 to June 1949, wind directions were observed on a 16-point
compass. These directions were converted to degrees before inclusion in
TD-6201.
92
-------
TABLE 1
Mandatory and Standard Levels TD-6201
Surface 1/46-6/49 7/49-12/55 1/56-6/57 7/57-12/60 1/61-Present
1000
950
900
850
800
750
700
650
600
550
500
450
400
350
300
250
200
175
150
125
100
80
70
60
50
40
30
25
20
15
10
7
5
4
3
2
1.5
1
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
it
it
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
it
*
*
*
*
*
*
*
*
*
*
it
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
it
it
it
it
it
*
*
it
it
it
it
it
it
it
*
*
*
it
it
it
it
it
*
*
*
*
*
*
*
*
*
*
*
*
*
*
93
-------
Background Information TD-6202
TD-6202: PERIOD:
National Meteorological Center (NMC)
Northern Hemisphere Sept. 1963 - Dec. 1970
Southern Hemisphere June 1966 - Dec. 1970.
These data were assimilated from normal International communication
channels and no detailed quality control measures were employed when converting
to TD-5683. The observations, therefore, were subject to the usual errors
inherent in such a collection.
The U/A observations contain all available mandatory and significant
levels transmitted under International agreement. The period of record may
vary from station to station, the general collection began Sept. 1963 and
continued through Dec. 1970 (Northern Hemisphere). Stations in the Southern
Hemisphere are usually not available until mid 1966 or later through Dec. 1970.
Relative humidities are derived statistically for RH's not reported
originally.
Background Information TD-6203
TD-6203: PERIOD:
National Meteorological Center (NMC) July 1971 - Dec. 1978
Air Force Global Weather Center (AFGWC) July 1971 - Dec. 1978
These U/A observations are a collection of data built by the National
Climatic Data Center (NCDC). These data were received from NMC and AFGWC.
NCDC converted these two data sources separately into TD-5681. Then these data
sources were combined giving priority to the NMC source.
94
-------
Areal coverage is worldwide.
The digital file contains: Station Identification (land and ships),
Latitude and Longitude of location, date/time, and elements:
LEVEL QUALITY INDICATOR - results by level.
TIME - elapsed time since release4
PRESSURE - by level in kilopascals.
HEIGHT - by level in geopotential meters.
TEMPERATURE - by level in degrees Celsius.
RELATIVE HUMIDITY - by level in degrees Celsius.
WIND - Direction and speed by level.
QUALITY CONTROL FLAGS - by level for time, pressure, height, temperature,
relative humidity, wind, and type of level.
95
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SPECIAL NOTES
QUALITY
U.S. data processed by the NCDC are subjected to extensive quality control
procedures. Suspect data are returned to a verifier for manual correction.
GTS data are subjected to various degrees of automated quality control by the
receiving agency. NCDC accepts the data as correct during the reformatting
procedure. Therefore, -the user must be prepared to perform his own quality
checks on GTS data. (The primary function of NMC and AFGWC is to produce
forecasts, not to provide an archive data base.)
When corrections are made to a level, that level will appear in the record
twice. The first occurrence of the level will be the original observed values,
with a level quality indicator of "2" or "4". The corrected data will appear
in the second occurrence of the level, with quality indicator of "6".
USE OF THE MANUAL
This manual was designed so that reference to other reference material
should be unnecessary. However, additional information may be obtained by
writing or calling:
National Climatic Data Center E/CC42
ATTN: USER Services Branch
Federal Building
Asheville, North Carolina 28801-2696
Telephone inquiries may be directed to:
Commercial 704 259-0682
FTS 672-0682
Read carefully, the general tape notations, and coding practices.
96
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TAPE FORMAT
MANUAL AND TAPE NOTATIONS
1. FILE (NCDC Variable Length Storage Structure)
A. Physical Characteristics
Data in this file are retained in chronological order by station.
Although library tapes are normally maintained as described below, different
characteristics including fixed length records can be furnished on request.
Additional charges may be accrued for special processing.
2. RECORD
A. Physical Characteristics
Each logical record contains one station's Upper Air (U/A)
Observation (Rawinsonde, Radiosonde, or Pibal) for each specific Upper Air
Sounding (normally 2 each day). The record consists of a control word, an
identification portion, and a data portion. The control word is used by the
computer operating system for record length determination. For many systems
this control word is transparent to the "users" program. The identification
portion identifies the observing station, latitude, longitude, day and time (of
release), and the number of repeating groups to follow. The data portion
contains the U/A meteorological values and the quality control flag fields for
each level. The data portion repeats for each level in the observation. The
maximum number of levels is 200. This number was chosen so that observations
containing one-minute wind data may be recorded in this format.
Record length
Blocked
Media
Density
Parity
Label
File
Variable with maximum of 7232 characters
12000 characters maximum
ASCII 9 Track
6250 BPI
Odd
ANSI Standard Labeled
1 File per tape
97
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B. FORMAT (VARIABLE RECORD)
1. The first five fields constitute the ID PORTION, and occur at
the beginning of each record. The next ten fields of the record contain the
DATA PORTION. The DATA PORTION is repeated for each level in the observation.
The maximum number of levels is 200.
710'
/ ^._n
Each logical record is of variable length with a maximum of
Each logical record contains a station's complete Upper Air
The form of a record is:
Observation for a specific release time
ID PORTION (32 characters) Fixed length
TAPE
FIELE
STATION
ID
XXXXXXXX
LAT
XXXX
LAT
CODE
X
LONG
XXXXX
LONG
CODE
X
DATE /TIME
XXXXXXXXXX
NUMBER
VALUES
XXX
001 002 003 004 005 006 007
)
DATA PORTION (36 Characters) repeated Number-Values Times
TAPE
FIELD
LVL-QLTY
INDCTR
X
TIME
XXXX
PRESSURE
XXXXX
HEIGHT
XXXXXX
TEMP
XXXX
RH
XXX
WIND
DIR
XXX
WIND
SPD
XXX
QUALITY
FLAGS
XXXXXX
TYPE OF
LEVEL
X
008 009 010 Oil 012 013 014 015 016 017
RH
XXX
WIND
DIR
XXX
WIND
SPD
XXX
QUALITY
FLAGS
XXXXXX
TYPE OF
LEVEL
X
TAPE 1998
FIELD
1999
2000
2001
2002
98
-------
TAPE FIELD
TAPE
RECORD POSITION
ELEMENT DESCRIPTION
001
002
003
004
005
006
007
008
009
010
Oil
012
013
014
015
016
017
(1958-1972)
(1973-1987)
(1988-2002)
001-008
009-012
013
014-018
019
020-029
030-032
033
034-037
038-042
043-048
049-052
053-055
056-058
059-061
062-067
068
(7125-7160)
(7161-7196)
(7197-7232)
STATION IDENTIFICATION
LATITUDE
LATITUDE CODE N/S
LONGITUDE
LONGITUDE CODE E/W
DATE AND TIME (YR/MO/DY/HR)
NUMBER OF DATA PORTION GROUPS THAT FOLLOW
LEVEL QUALITY INDICATOR
TIME (ELAPSED TIME SINCE RELEASE)
PRESSURE
HEIGHT
TEMPERATURE
RELATIVE HUMIDITY
WIND DIRECTION
WIND SPEED
FLAG FIELD (QUALITY FLAGS)
TYPE OF LEVEL
DATA GROUPS IN THE SAME FORM AS TAPE FIELDS
008-017. REPEATED AS MANY TIMES AS NEEDED
TO COMPLETE ONE UPPER AIR OBSERVATION. A
MAXIMUM OF 200 LEVELS ARE POSSIBLE.
99
-------
The following COBOL and FORTRAN statements are to be used as guidelines only.
NCDC recognizes the fact that many different types of equipment are used in
processing these data. It is impossible to cover all the idiosyncrasies of
every system.
Typical ANSI COBOL Data Description.
This ANSI Standard COBOL Data Description is expected to work on most
systems.
FD UA-DATA
LABEL RECORDS ARE STANDARD
RECORDING MODE D
BLOCK CONTAINS 12000 CHARACTERS,
01 UA-RECORD.
02 STATION-NUMBER
02 LATITUDE.
03 LATITUDE-NUM
03 LATITUDE-ALPH
02 LONGITUDE.
03 LONGITUDE-NUM
03 LONGITUDE-ALPH
02 DATE-TIME.
03 YEAR
03 MONTH
03 DAYS
03 HOUR
02 NUMBER-OF-LEVELS
02 LEVEL-RECORD
OCCURS 1 to 200 TIMES
03 QUALITY-INDICATOR
03 ELAPSED-TIME
03 PRESSURE
03 HEIGHT
03 TEMPERATURE
03 RELATIVE-HUMIDITY
03 WIND-DIRECTION
03 WIND-SPEED
03 FLAGS.
04 TIME-FLAG
04 PRESSURE-FLAG
04 HEIGHT-FLAG
04 TEMPERATURE-FLAG
04 R-H-FLAG
04 WIND-FLAG
04 TYPE-OF-LEVEL
PICTURE X(8).
PICTURE 9999.
PICTURE X.
PICTURE 99999.
PICTURE X.
PICTURE 9(4).
PICTURE 99.
PICTURE 99.
PICTURE 99.
PICTURE 999.
DEPENDING ON NUMBER-OF-LEVELS,
PICTURE X.
PICTURE 999V9.
PICTURE 999V99.
PICTURE S99999
SIGN LEADING SEPARATE.
PICTURE S99V9
SIGN LEADING SEPARATE.
PICTURE 999.
PICTURE 999.
PICTURE 999.
PICTURE X.
PICTURE X.
PICTURE X.
PICTURE X.
PICTURE X.
PICTURE X.
PICTURE X.
100
-------
FORTRAN 77 Example 1.
This description is for those systems that can handle variable blocked
records normally.
IMPLICIT INTEGER (A-Z)
OPEN (10,FILE = 'FILENAME'.ACCESS = 'SEQUENTIAL1, STATUS =» 'OLD',
+ RFORM = 'VB'.MREL =* '1230',TYPE = 'ANSI',BLOCK = '12000')
C LAST line of OPEN statement is SPERRY UNIQUE
CHARACTER*8 STNID
CHARACTER*! LATA,LONA,QIND(200),TIMEF(200),PRESSF(200) ,
+ HGTF(200),TEMPF(200),RHF.(200),WINDF(200),TYPLEV(200)
REAL*4 LAT,LON,ETIME(200),PRESS(200),HGT(200),TEMP(200)
DIMENSION ETIME(200),PRESS(200),HGT(200),
+ TEMP(200),RH(200),WD(200),WS(200)
READ (10,20,END=999) STNID,LAT,LATA,LON,LONA,YEAR,
+ MONTH,DAY,HOUR,NUMLEV,(QIND(J),ETIME(J),
+ PRESS(J),HGT(J),TEMP(J),RH(J),WD(J),WS(J),
+ TIMEF(J),PRESSF(J),HGTF(J),TEMPF(J),RHF(J),
+ WINDF(J),TYPLEV(J),J=1,NUMLEV)
20 FORMAT (A8,F4.0,A1,F5.0,A1,14,3(12),13,200(A1,F4.1,F5.2,
+ F6.0,F4.1,3(I3),7A1))
IBM JCL NOTES.
(1) For ASCII Variable specify:
LREC = 7236
RECFM = DB
OPTCODE - Q
(2) For EBCDIC Variable specify:
LRECL = 7236
RECFM = VB
101
-------
FORTRAN 77 Example 2.
This description is for those systems that can't handle variable blocked
records normally.
$ MOUNT/FOREIGN/BLOCKSIZE=12000 MT: tapename TAPE: ! THIS IS VAX
! UNIQUE
PROGRAM TAPEREAD
IMPLICIT INTEGER (A-Z)
• • • • •
OPEN(1,FILE=TAPE:',ACCESS='SEQUENTIAL',FORM=FORMATTED',
+ STATU S='OLD',READONLY)
CHARACTER BUFFER*12000 ! YOUR MACHINE MUST SUPPORT
CHARACTER *8 STNID ! CHARACTER VARIABLES THIS LARGE
CHARACTER*! LATA,LONA,QIND(200),TIMEF(200),PRESSF(200),
+ HGTF(200),TEMPF(200),RHF(200),WINDF(200),TYPLEV(200)
REAL*4 LAT,LON,ETIME(200),PRESS(200),HGT(200),TEMP(200)
DIMENSION ETIME(200),PRESS(200),HGT(200),TEMP(200),RH(200),
+ WD(200),WS(200)
• • • • •
NBYTES=0
5 NBEG=1
READ( 1,101 ,END=99)BUFFER IREAD IN PHYSICAL RECORD (BLOCK)
10 NBEG=NBEG+NBYTES
READ(BUFFER(NBEG:NBEG+3,102)NBYTES IREAD THE CONTROL WORD
IF( NBYTES.EQ.O )GO TO 5
READ(BUFFER(NBEG+4:NBEG+NBYTES-1),103)STNID,LAT,LATA,LON,LONA,YEAR,
+ MONTH,DAY,HOUR,NUMLEV,(QIND(J),ETIME(J),PRESS(J),HGT(J),TEMP(J),
+ RH(J),WD(J),WS(J),TIMEF(J),PRESSF(J),HGTF(J),TEMPF(J),RHF(J),
+ WINDF(J),TYPLEV(J),J=1,NUMLEV)
GO TO 10
99 CONTINUE
STOP 'FINISHED'
101 FORMAT(A)
102 FORMATCI4)
103 FORMATC A8 ,F4 .0 ,A1 ,F5 .0 ,A1 ,14 ,3( 12) , 13 ,200(A1 ,F4 .1 ,F5.2 ,
4-F6.0,F4.1,3(I3),7Al))
END
102
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TAPE
FIELD
TAPE
RECORD
^POSITION
ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
001
1-8 STATION- STATION IDENTIFICATION—For U.S. controlled and
ID cooperative stations, the WBAN number (TD-6201).
For stations received through GTS, the WHO number
(TD-6202). TD-6203 has general WMO numbers but
some are WBAN numbers. This field may contain
alphabetic characters for ships and remote sensed
observations. Numeric station numbers are right
justified and zero filled, while alphanumeric
station indentifiers are left justified and blank
filled. If unknown, this field contains
"99999999". If the station identification is
unknown, both latitude and longitude must be
present.
002 9-12 LATITUDE LATITUDE—The station latitude in degrees and
minutes. When unknown, this field contains
"9999". Latitude will not normally appear for.
land stations.
003
13 LATITUDE
CODE
LATITUDE CODE— CODE used to indicate the
Northern (N) or Southern (S) latitudes.
004
14-18 LONGITUDE
LONGITUDE—The station longitude in degrees and
minutes. When unknown, this field contains
"99999". Longitude will not normally appear for
land stations.
005
19 LONGITUDE LONGITUDE CODE—CODE used to indicate Longitudes
CODE East (E) or West (W).
006
20-29 DATE-TIME
DATE/TIME—The scheduled time of the observation,
as defined by WMO. The format of date/time is
YYYYMMDDHH, i.e., year, month, day, hour. This
field may never be unknown.
20-23 YEAR
YEAR-This is the Year of record. Range of values
are 1946-current year processed.
24-25 MONTH
MONTH-This is the Month of record. Range of value
are 01 to 12.
103
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TAPE
TAPE RECORD
FIELD POSITION
ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
26-27
DAY
DAY-This is the Day of record. Range of values
are 01 to 31.
28-29
HOUR
HOUR-This is the Hour of record. Range of value
are 00 to 23. Hour is GMT. Normal scheduled
observation times are 00 and 12 GMT. For selected
periods and areas observations may have been taken
at other times, especially 06 and 18 GMT.
007 30-32 NUMBER- NUMBER-OF-REPEATING-GROUPS—This number represents
REPEAT- the number of data levels found in the current
GROUPS observation, including edited levels. Range of
values are 001-200. Two hundred is the maximum
number of levels.
008 33 LEVEL- LEVEL-QUALITY-INDICATOR—Denotes the results of
QUALITY- any quality controls applied to this level.
INDCTR Range is as follows:
0 Original values are correct.
1 Original values missing.
2 Original values doubtful, a corrected level
follows.
3 Original values doubtful, uncorrected.
4 Original values in error, a corrected level
follows.
5 Original values in error, uncorrected.
6 Corrected level.
9 Level not checked.
A-Z Indicators supplied by NMC. NMC Indicators
have changed many times over the years. If
you wish to use their indicators you will
have to contact NMC.
009 34-37 TIME- TIME—The elapsed time since the release of the
SINCE- sounding in minutes and tenths. If the elapsed
RELEASE time is not known, this field contains "9999".
Range is 0001 through 9999. Available only for
U.S. quality controlled stations beginning Jan
1981.
104
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TAPE
TAPE RECORD
FIELD POSITION
ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
010 38-42 PRESSURE- PRESSURE—Atmospheric pressure at the current
AT-LEVEL level in kilopascals and hundredths. If unknown,
this field contains "99999". (TD6201 only -
Subsurface levels were generated from Jan. 1, 1981
through Feb. 28, 1986. The values were always
unknown. This practice was stopped Mar. 1, 1986.
Oil 43-48 HEIGHT- HEIGHT—Geopotential height of the current level
AT-LEVEL in whole meters. If unknown, this field contains
"-99999". Range of values are -99999 through
99999.
012 49-52 TEMPERATURE TEMPERATURE—The free air temperature at the
AT-LEVEL current level in degrees and tenths Celsius. If
unknown, this field contains "-999". Range of
values -999 through #999.
013 53-55 RELATIVE- RELATIVE-HUMIDITY—The relative humidity at the
HUMIDITY current level in whole percent. If unknown, this
AT LEVEL field contains "999". In TD-6202, relative'
humidities are derived statistically for RH's not
reported originally.
014 56-58 WIND- WIND-DIRECTION—Direction of the wind at the
DIRECTION current level in whole degrees (nearest five
AT-LEVEL degrees for observations received through GTS). If
unknown, this field contains "999".
015 59-61 WIND-SPEED WIND-SPEED—Speed of the wind in whole meters per
AT-LEVEL second. If unknown, this field contains "999".
105
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TAPE
TAPE RECORD
FIELD POSITION
ELEMENT
NAME
CODE DEFINITIONS AND REMARKS
016 62-67 QUALITY- QUALITY-FLAG-FIELD—This field contains the
FLAGS results of any quality control procedures,
identifying each individual element found in error
(see table below).
QUALITY CONTROL FLAG
0 Element is correct
1 Element is doubtful
2 Element is in error
3 Replacement value
4 Assumed or estimated value
9 Element not checked
A-Z Indicators supplied by NMC. NMC flag
indicators have changed many times over the
years. If you wish to use their indicators
you will have to contact NMC.
62
TIME-QF
Time Quality Flag
63
PRESSURE-QF Pressure Quality Flag
64
HEIGHT-QF Height Quality Flag
65
TEMPERATURE- Temperature Quality Flag
QF
66
RELATIVE- Relative Humidity Quality Flag
HUMIDITY-QF
67
WIND-QF
Wind Quality Flag
017
68
TYPE-OF
LEVEL
TYPE OF LEVEL FLAG—See Table below.
0 Surface
1 Mandatory
2 Significant
3 Generated
4 Tropopause
5 Maximum wind
9 Other/unspecified
NOTE: TD-6201 through December 1975 will contain
Type of Level Flags 0,1, and 9 only. The
significant flag is not present.
106
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APPENDIX E
DESCRIPTION OF THE TD-9689 FORMAT
This description is reproduced from documentation provided by the National
Climatic Data Center (NCDC).
107
-------
FILE NAME:
TIME PERIOD:
GEOGRAPHIC COVERAGE:
FILE SIZE:
FORMAT:
FILE STRUCTURE:
CONTENTS:
ABSTRACT:
MIXING HEIGHT STUDIES (TD-9689).
January 1, 1960 through December 31, 1964 and various
later years.
Selected upper air stations in the United States.
One magnetic tape; 9-track, odd parity, 1600bpi, ASCII
mode, labeled and two magnetic tapes; 9-track, odd
parity, 6250bpi, ASCII mode labeled. Copies of these
data are available on magnetic tape (EBCDIC or ASCII
mode) and other computer media.
34 characters per record, 10 records per block.
Morning and afternoon mixing heights for the years
1960-1964 were calculated for 62 stations by NCDC for
the Environmental Protection Agency. These data are on
one reel of 1600bpi magnetic tape. Mixing heights for
later years can be computed on demand. A great many of
these studies for later years have been generated and
are stored on two reels of 6250bpi magnetic tape.
The major parameters that make up this file are date,
morning type indicator, morning (near minimum) mixing
depth (meters), morning average wind speed (meters per
second to lOths) through the mixing depth, morning
average surface wind speed, afternoon type indicator,
afternoon (near maximum) mixing depth, afternoon average
wind speed through the mixing depth, and afternoon
average surface wind speed.
The data utilized in generating this file are hourly
surface weather observations (TD-3280), and upper air
observations (TD-6201) taken at 0000 GMT and 1200 GMT.
Since it takes two data files to generate a mixing
height , two different stations (upper air and surface)
may be used. Usually this involves a surface station
close to the user's area of interest and an appropriate
nearby upper air station.
For a mixing height study, it is assumed that a well
mixed unsaturated atmosphere will have a lapse rate that
is dry adiabatic (9.8 degrees C per kilometer). The
morning mixing height is then defined as the height
above ground level where the dry adiabatic extension of
the morning minimum surface temperature plus 5 degrees C
intersects the vertical temperature profile (RAOB)
observed for the 1200Z sounding. The plus 5 degrees C
is an overstatement of average effects of the urban heat
island and therefore includes some surface solar
heating. The estimated mixing height applies at the
time and place where the surface temperature has
108
-------
increased 5 degrees C above the minimum. The afternoon
mixing height is calculated in the same manner, using
the 1200Z RAOB, but this time only the maximum surface
temperature is used. In addition, the average wind
speed through the mixing depth is calculated. Thus, for
each day , a morning and afternoon (maximum) mixing depth
is given along with the average wind speed through the
mixing depth and precipitation if it occurred
(considered to be a cleaning agent of the atmosphere).
An inventory of this file is available to users from the
NCDC. There are no known related files.
This file is also available for purchase from the NCDC.
109
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TAPE POSITION
MIXING HEIGHT STUDY
(34 Characters, Blocked 10)
ITEM
1-5
6 9
10
11-12
13-23
*13
14-17
18-20
21-23
24-34
25-28
29-31
32-34
Station number
Year, month
Season
1 = Dec, Jan, Feb
2 = Mar, Apr, May
3 = Jun, Jul, Aug
4 = Sep, Oct, Nov
Bay
Morning
Type
1 = No Precip
2 = Precip
3 = Cold Advection
4 = Missing
Mixing depth (Meters)
Average wind speed thru mixing depth
Average surface wind speed
Afternoon
Type - 1, 2, 3, or 4
Mixing Depth
Average wind speed thru mixing depth
Average surface wind speed
Period 1960 - 1964
Type CBlank,C or P)
Blank • -Missing or -no Precipitation
C » Cold Advection
"P * Precipitatitjn
110
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APPENDIX F
DESCRIPTION OF THE TD-9773 FORMAT
This description is reproduced from documentation provided by the National
Climatic Data Center (NCDC).
Ill
-------
FILE NAME:
TIME PERIOD:
GEOGRAPHIC COVERAGE:
FILE SIZE:
FORMAT:
FILE STRUCTURE:
CONTENTS:
ABSTRACT:
STABILITY ARRAY-STAR (TD-9773).
Not time dependent.
300 United States and Select World-Wide Stations.
8 magnetic tapes; 9-track, odd parity, 1600bpi, ASCII
mode, labeled. Copies of these data are available on
magnetic tape (EBCDIC or ASCII mode) and other computer
media.
84 characters per record, 10 records per block.
Data are sorted on each magnetic tape by header number
or station number (WBAN or WHO).
The major parameters that make up this file are wind
direction (16 points and calm), stability class (A-G),
wind speed (kts) frequencies, station ID, and beginning
and ending year. The STAR output consists of monthly,
seasonal, or annual frequency and percent frequency
tables of wind direction versus wind speed groups for
each stability category.
STAR was born from the work of Pasquill (1951), Turner
(1964), and Martin and Tidvart (1968). It provides, at
least roughly, the diffusion characteristics for the
lowest part of the atmosphere and biosphere. It is an
objective method of determining stability from readily
available surface meteorological observations utilizing
only the variables of ceiling height, total sky cover,
and wind direction and speed as input. The methodology
employed recognizes that stability near the ground is
dependent primarily upon net radiation and wind speed.
Wind direction is not a factor in objective
determination of stability categories. Without the
influence of clouds, insolation (incoming radiation)
during the day is dependent mainly upon the solar
elevation, which is a function of time of year, time of
day, and station location. When clouds
cover and thickness decrease incoming
radiation. In this system, insolation is
solar elevation and modified for existing conditions of
total sky cover and ceiling height. At night, estimates
of outgoing radiation are again based on total sky cover
and ceiling height. The STAR output consists of
frequency and percent frequency tables of wind direction
versus wind speed groups for each stability category-
This system produces seven categories ranging from
extremely unstable (A) to neutral (D) to extremely
stable (G) and can be summarized on a monthly, seasonal,
or annual basis.
exist, their
and outgoing
estimated by
112
-------
NCDC can produce a STAR for any year or number of years
for any station (world-wide) whose hourly or 3-hourly
surface meteorological observations are stored in
TD-3280 or TD-9999 AFDATSAV files. An optional output
of the STAR that NCDC can generate is formatted, 100
characters per record/10 records per block, individual
surface meteorological observations and associated
stability categories on magnetic tape or other computer
media.
A STAR TABULATIONS MASTER LIST (Index) is available to
users from the NCDC. There are no known related files.
This file is available for purchase from the NCDC.
113
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