VORTEX 1995 Mobile and Fixed CLASS Format Upper Air Sounding Data sets 1.0 General Description This is one of the upper air sounding data sets developed for the Verification of the Origins of Rotation in Tornadoes EXperiment (VORTEX) conducted from 01 April to 15 June 1995. Included in this data set are four fixed sites (Altus, Ardmore and Woodward OK and Lubbock TX), as well as 5 mobile sounding systems (4 NSSL; 1 NCAR). The soundings from all sites were released on an as requested basis. The final data set consists of 10-sec resolution files. The area covered by the experiment extends from approximately 91W to 107W longitude and 31N to 40N latitude. 2.0 Detailed Data Description For each sounding, this dataset contains the data type, project ID, site ID, site location, release time, radiosonde type, meteorological and wind data processors, and the operators name and comments. Additionally, for each sounding level, this dataset contains the time from release, pressure, temperature, dew point, relative humidity, U and V wind components, wind speed and direction, ascent rate, balloon position data, altitude, and quality control flags (see QC code description). QC Code Description Code Description 99.0 Unchecked (QC information is "missing.") ("UNCHECKED") 1.0 Checked, datum seems physically reasonable. ("GOOD") 2.0 Checked, datum seems questionable on physical basis. ("MAYBE") 3.0 Checked, datum seems to be in error. ("BAD") 4.0 Checked, datum is interpolated. ("ESTIMATED") 9.0 Checked, datum was missing in original file. ("MISSING") 2.1 Data Remarks Due to the methodology of the calculation of altitude by the NSSL CLASS system, the 10 sec files were entirely regenerated from the raw 1.5 sec resolution meteorological data. The NSSL CLASS system included all data points in its derivation of the 10 sec data set and altitudes were calculated using all data points. When the data becomes bad there can be large errors in the calculated altitudes. OFPS regenerated a 10 sec data set by first removing outliers in pressure, temperature and/or relative humidity from the 1.5 sec resolution data. This was done by allowing certain pressure changes per second, starting at 1.5 mb/sec and falling off with pressure by the exponential of the pressure weighted pressure difference. Next, the temperature was checked for extreme superadiabatic and inversion layers. Finally, the relative humidity underwent a gross consistency check (allowing 5% change per second). If any of these tests failed, the entire data point was removed. From the remaining data points a 10 sec data set was reinterpolated using a 10 sec average centered on the 10 sec level. The wind and positional data remained unchanged and were simply inserted into the data set. Some of the soundings taken during the VORTEX project were purposely launched into updrafts of tornadic thunderstorms. Such soundings were unable to be reprocessed by the above routine but, in contrast to 1994, these soundings were reprocessed for VORTEX 95. The processing was the same in all but two respects. First, ANY pressure decrease of any size was allowed and NO pressure increase of any size was allowed. This was possible in VORTEX 95 because the updraft soundings were much better `behaved' than in VORTEX 94. The other difference in the processing was that extreme superadiabatic layers were allowed upon exiting the updraft, this is to allow data as the radiosonde becomes acclimated to the out-of-updraft conditions. The following lists contain the updraft soundings that were processed in this way. The format is: MDDTTTT (M=month, D=day, T=time in UTC) NSSL1 NSSL2 NSSL3 NSSL4 ------------------------------------------------------------- 4162226 4172311 5230013 5072025 4300017 5122307 5072107 5170104 5130042 5130043 5172214 5230104 5170104 5222138 6030046 5222232 6082121 6040120 6090046 6082014 6090050 Some of the NSSL mobile soundings were not able to undergo ANY reprocessing. NO outlier removal, or quality control was applied. The files include: 5130003.ns1 (very noisy data in updraft) 6040116.ns2 (data in file is bad) 5122258.ns4 (no data in file) 5170143.ns4 (all data is at the surface) Some of the surface altitude data in the original NSSL files was incorrect. To get an approximate altitude OFPS used 1x250,000 topolographical maps. These allow an accuracy of about 20 m. The latitude/longitude location given in the header was used to find the altitude on the maps. The files affected include: 4191310.ns4 6022321.ns2 6022345.ns2 6030046.ns2 Four of the NSSL mobile soundings did not have any high resolution data files available. In these cases, reprocessing was impossible, however, the complete quality control processing was conducted. The files include: 4011555.ns4 4171712.ns2 4171731.ns4 4180039.ns2 The NCAR Mobile and the four fixed sites underwent a similar type of processing by the NCAR/Surface and Sounding Systems Facility (SSSF) for information on their procedures contact: Eric Miller NCAR/SSSF P. O. Box 3000 Boulder Co 80307-3000 Two of the Altus (LTS) soundings did NOT pass through any of the NCAR/SSSF reprocessing, so some of the data in these files may be questionable, they are: 3202105 4271927 3.0 Quality Control Processing This data set underwent a two-stage QC process. First, the data set underwent internal consistency checks. This included two types of checks, "reasonable" limit checks on all parameters and rate-of-change checks on temperature, pressure and ascension rate. Second, each sounding was visually examined to verify those parameters that are too variable for automatic checks (wind speed, wind direction and moisture). This stage of the QC process also allows for a verification of the QC flags generated by the automatic checks. NOTE----------------------------------------------------------------------- The NSSL updraft soundings (listed above) did not go through ANY quality control processing. NOTE----------------------------------------------------------------------- 4.0 References