Section 3: Sounding Data Several different organizations operated sounding equipment during the ERICA field study. These organizations include the National Weather Service (NWS), the U.S. Navy, the Canadian Atmospheric Environment Service (AES), the National Center for Atmospheric Research (NCAR), and the Air Weather Service (AWS). Map 3.1 shows the locations of the land-based sounding sites in eastern North America. The ERICA FPS contains Drop Location Maps for each IOP (in 6-hour windows) showing where dropsondes were launched. Each organization provides the data in a different format, and, in some cases (e.g. the NWS), the data are formatted differently in different versions. Quality controlled versions of the data from NCDC often supplant earlier field quality versions. Table 3.1 will assist in clearing the confusion surrounding multiple versions of sometimes overlapping data sets. Each of the source data sets are described in different sections below. 3.1 Master Sounding Files Robert Cohen of Drexel University has prepared a set of Master Sounding Files which contains all of the ERICA soundings in a common format, with uniform quality-checking. We believe that this set will satisfy the needs of most researchers. 3.1.1 Master Sounding Files Form: digital Size: 135 Mbytes Volume: 1 tape This is the standard ERICA Data Center sounding data product. Version two of this set contains 25,404 soundings from the following sources: LeSonde data, version 2 (see section 3.3.1), TD-6201 NWS soundings, version 1 (see section 3.2.1) (without Bermuda data) CYCLE-format Canadian soundings, version 1 (see section 3.2.3.1) Bermuda and ship soundings from the NMC history tapes, version 1 (see section 3.3.6) AWS drop data from the NMC history tapes, version 1 (see section 3.3.3), Yarmouth data from AES, version 2 (see section 3.2.3.2) CLASS data, version 2 (see section 3.3.4) Table 3.1 summarizes the current status of the ERICA sounding data. Each of the different source data sets have been subjected to different degrees of quality control before arriving at the ERICA Data Center. See the appropriate section for more information about individual sounding sets. Although each set used a different set of quality flags, a common set of flags has been used in the Master Sounding Files. Various quality checking programs have been run on the data, which provide additional commentary on their quality. Additional files are provided containing the comments generated by these programs and from other sources (i.e. comments added by hand either at the Data Center or at the sounding site). The ERICA soundings are sorted synoptically for the period of December 1, 1988 to February 28, 1989. Height (hydrostatic), temperature, relative humidity, wind direction and speed, elapsed time, and data quality flags are reported for each sounding at 10 mb levels. The data are organized in fixed record-length format, with one sounding per record. The format is identical to the one used with the final versions of the GALE sounding data. 3.1.2 Skew-Ts of ERICA Soundings Form: paper Size: 8.5"x11" Volume: one page per sounding Skew-T diagrams can be produced for any sounding or drop in the Master Sounding files. NCAR has also provided volumes of skew-Ts for the LeSonde drops (see section 3.3.2) and CLASS soundings (see section 3.2.5). 3.1.3 Constant Pressure Charts of ERICA Soundings Form: paper Size: 8.5"x11" Volume: 1-20 pages per sounding time Constant pressure charts for the entire ERICA period are available for the surface and at 50 mb intervals from 1000 mb to 100 mb. The data are drawn from the Master Sounding Files (see section 3.1.1). The charts are created at the Data Center using NCAR graphics. Researchers interested in this product might also be interested in the NMC North American Constant Pressure Analyses (see section 3.2.1). 3.2 Land-Based Soundings Map 3.1 shows the locations of all of the land-based sounding sites in eastern North America whose data are archived at the ERICA Data Center. The sites are listed in Appendix F. 3.2.1 NCDC Upper Air Data (TD-6201) Form: digital Size: 53 Mbytes Volume: 1 tape NCDCs TD-6201 files are the best source of research quality soundings from NWS sites. The original data include all of the special ERICA six and three hourly NWS soundings. All thermodynamic and wind data levels are included, as well as every 50 mb level. The TD-6201 file is produced after all of the original data (recorded on cassettes at the NWS sites) are reprocessed at NCDC. These data are free of communication noise and have been carefully checked at NCDC. There are 18,777 soundings in the TD-6201 data set for the ERICA period. This set includes NWS and Bermuda soundings, typically made twice per day, at 00Z and 12Z. (The Bermuda soundings in this set do not include winds, and so these Bermuda data were not included in the Master Sounding Files.) Each daily file in this set holds all the TD-6201 sounding data for that day. Within the files the data are sorted by hour and station. These data are included in the Master Sounding Files (see section 3.1.1) and researchers might find that product more convenient to work with. 3.2.2 NMC North American Constant Pressure Analyses Form: microfilm, paper Size: 8.5"x11" (paper) Volume: 2 analyses per day, 3 rolls of microfilm total These operational charts are prepared twice a day by NMC and archived on microfilm by NCDC. Each reel contains the charts for 00Z (at 850, 700, 500, 300, and 200 mb levels) and 12Z (at 100, 50, 30, and 10 mb levels, in addition to the 00Z levels). There is one roll of microfilm for each month of the field study. The microfilms may be borrowed, or select paper copies can be made at the Data Center. Note that more complete and more thoroughly quality-checked data from these sites are also available in the ERICA Master Sounding Files. Constant Pressure Charts (without analyses) can be made from the Master Sounding set (see section 3.1). 3.2.3 Canadian Soundings 3.2.3.1 CYCLE-Format Canadian Soundings Form: digital Size: 41 Mbytes Volume: 1 tape This set contains the data from the Canadian Climate Center (CCC) of the Atmospheric Environment Service (AES) of Canada. This set includes all Canadian regular upper-air sites except Yarmouth (see section 3.2.3.1). 5,196 of the 5,585 CYCLE-format soundings are included in the Master Sounding Files (section 3.2.1). The data are all in one file, sorted by month, site, day, and hour. 3.2.3.2 Yarmouth Soundings Form: digital Size: 14 Mbytes Volume: 1 tape This set contains the data from the Yarmouth, New Brunswick, sounding site. This site used new sounding equipment developed at VIZ Manufacturing, and the post-processed data are in a different format from the other Canadian soundings. The first version of these data (54 soundings) were drawn from the ADPUPA data on the history tapes and were merged into the first version of the Master Sounding Files. This second version of the Yarmouth data came from Norman Donaldson at AES, and includes 195 soundings. Some editing was done to these data at the Data Center by Robert Cohen. These data are included in the second version of the Master Sounding Files (see section 3.1.1). 3.2.4 CLASS Soundings Form: digital Size: 40 Mbytes Volume: 1 tape The CLASS systems were developed by NCAR as relocatable sounding sites. Eight CLASS sites were deployed in support of ERICA, as shown on map 3.1. The second version of these data arrived at the Data Center in December, 1989. There are 636 CLASS soundings (seven of which are unusable). Some editing and corrections were applied to these data at the Data Center by Robert Cohen. There are two files for each sounding, one contains 5 mb interpolated data, the other contains 10 second wind data and high resolution (approximately 4 Hz) thermodynamic data. These soundings are included in version 2 of the Master Sounding Files (see section 3.1.1). 3.2.5 NCAR Skew-Ts of CLASS Soundings Form: paper Size: 8.5"x11" Volume: 650 pages total, in eight volumes NCAR has provided copies of a eight volume set which contains Skew-Ts of the ERICA CLASS soundings. Each volume contains all of the soundings from one site. Two versions of these skew-Ts were prepared; researchers should be sure to use the second version. These skew-Ts have wind vectors instead of barbs to allow room for 5 mb winds to be displayed. The directions are opposite the traditional wind barb conventions. Note that these data are merged into the Master Sounding Files, and skew-Ts of these soundings can be generated at the Data Center from the Master Sounding Files (see section 3.1.2). 3.3 Other Soundings Dropsondes of two types were used during ERICA. The WP-3Ds and the Electra dropped the new LORAN-based LeSondes; the AWS dropped the Omega-based ODWs. In an efforts to provide the most comprehensive sounding data possible, Chuck Browne has worked here at the Data Center to extract portions of aircraft flight level data and format them as soundings. Soundings are taken by the U.S. Navy at sea; these soundings are particularly valuable to ERICA, providing more sounding data over the ocean. 3.3.1 LeSonde Drop Data Form: digital Size: 40 Mbytes Volume: 1 tape The LeSonde drop equipment and instrument packages were designed at NCAR as a sonde safe to drop over land. These sondes are also believed to be better than ODWs in the quality and quantity of the data that they provide. The second version of the post-processed LeSonde drop data from NCAR include 5 mb interpolated data and 1 second thermodynamic data with 30 second winds. The set includes data from 376 drops, ordered by aircraft, date, hour, minute These data are included in the Master Sounding Files (see section 3.1.1) and researchers might find that product more convenient to work with. 3.3.2 NCAR Skew-Ts of LeSonde Drops Form: paper Size: 8.5"x11" Volume: 400 pages total, in two volumes NCAR has provided copies of the two-volume set of skew-Ts for the ERICA LeSonde drops. Volume one contains the skew-Ts for drops in IOPs 1 through 4. Volume 2 contains IOPs 5 through 8. Two versions of these skew-Ts were prepared; researchers should be sure to use the second version. These skew-Ts have wind vectors instead of barbs to allow 5 mb winds to be displayed. The directions are opposite the traditional wind barb conventions. Note that these data are merged into the Master Sounding Files, and skew-Ts can be generated from the Master Sounding Files (see section 3.1.2). 3.3.3 AWS Dropsonde Data Form: digital Size: 800 Kbytes Volume: 1 tape These are the AWS drops which were done in support of ERICA by the Air Weather Service as part of NWSOP (National Winter Storms Operations Plan). Significant and mandatory level data are available from the 170 drops made during the ERICA field study. Most of these data were extracted from the NMC History Tapes (see section 7.1), but 16 had to be typed in from the paper copies of the soundings provided by the AWS. About 20 drops are outside the ERICA region (in the Gulf of Mexico). These data are included in the Master Sounding Files (see section 3.1.1) and researchers might find that product more convenient to work with. 3.3.4 Soundings Extracted from Flight Level Data Form: digital Size: 19 Mbytes Volume: 1 tape Ascents and descents of greater than 200 mb by ERICA research aircraft are separated from the rest of the flight level data and treated as it they were soundings. The post processed WP-3D Flight Level Data (see section 2.1.1) and the post- processed EL&SL Flight Level Data (see section 2.2.1) were used. 148 soundings were extracted from the WP-3D data, 38 from the Electra, and 47 from the Sabreliner. These soundings consist of one second flight level data. 3.3.5 Marine Sounding Data (TD-6210) Form: digital Size: 100 Kbytes Volume: 1 tape These are the U.S. Navy soundings taken at sea during the ERICA field study. These data are not yet available but are expected to be available in the Summer of 1990. 3.4 PSU Wind Profiler Data Form: digital Size: 10 Mbytes Volume: 1 tape These data were provided by Professor Greg Forbes of Penn State and include hourly profiles of the horizontal and vertical wind velocities and SNR (signal to noise ratio) from three profiler sites. The profilers were deployed at: Otis AFB, MA UHF 41.65N 70.53W Shanty McAlevys Fort, PA VHF 40.65N 77.88W Crown, PA VHF 41.39N 79.28W The profilers were in operation throughout the field study, but due to equipment problems they were down occasionally. Sustained outages are listed below: Otis: Down from 8 to 23 December, and for 12 hours on 14 February. Shanty: Down from 7 to 8, 14 to 17, and 21 February. Crown: Down for 18 hours on 14-15 February. Additional data were collected from the Otis site and are archived at Penn State. These data include hourly profiles of RASS (Radio Acoustic Sounding System) virtual temperatures (during non-precipitation situations only), and 5-minute horizontal velocity, vertical velocity, SNR, and individual beam velocities and spectra data. The RASS data have not yet been recalibrated, but select periods may be recalibrated upon request. These additional data are more voluminous, occupying one tape for each day (for IOPs only). Interested researchers should contact Greg Forbes. Researchers may also wish to contact Penn State to discuss data quality.