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 ------- 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 ------- 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 ------- 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. iii ------- 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 ------- 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 ------- 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. vii ------- 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 ------- 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. ------- 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. 3 ------- 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 ------- 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) ------- 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. ------- 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. ------- 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. ------- 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. ------- 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). 10 ------- 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. 11 ------- 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 12 ------- 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 13 ------- 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 14 ------- 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 ------- 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 16 ------- 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. 17 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- |