VORTEX Mobile and Fixed CLASS Upper Air Sounding Datasets 
     
     
     1.0  General Description
     
          This is one of the upper air sounding datasets developed for the
     Verification of the Origins of Rotation in Tornadoes EXperiment
     (VORTEX) conducted from 01 April to 15 June 1994.  Included in this
     dataset are two fixed sites (Lubbock TX and Ardmore OK) 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 dataset 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, sonde type, meteorological and wind
     data processors, and the operators name and comments.  Additionally,, for
     each level of the sounding, the dataset contains time from release, pressure,
     temperature, dewpoint, 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
     CLASS system, the 10 sec files were entirely regenerated from the raw 1.5
     sec resolution meteorological data.  The CLASS system included all data
     points in its derivation of the 10 sec dataset 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 dataset 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
     datapoint was removed.  From the remaining data points a 10 sec dataset
     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 dataset.  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 and were simply converted to OFPS CLASS Format and all
     flags were set to unchecked.  Also, such files have a comment in the
     header that specifies that they have been unchecked.  The following lists
     contain the files that were NOT able to be reconstructed.  
     
     The format is:  MDDTTTT  (M=month, D=day, T=time in UTC)
     
     NSSL1     NSSL2     NSSL4     LUB       1FO       NCAR
     4262156   5250059   4262144   4271742   4252038   5300105
     5262259   5260000   5062325   4272026   4271725   6012358
     5270015   6110101   5070041   4272323   5062314   6081614
     5270111   6110227   5070119   6161417             6081945
     5292321             5070141   
     6012221             5250006
     6020032             5252219
     6110043             6020102
     6110151             6081719
                         6110052
     
     
     3.0  Quality Control Processing
     
          This dataset underwent a two-stage QC process.  First, the dataset
     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.             
     
     4.0  References