May 21, 1998

MEMORANDUM TO:  Record
FROM:           Dennis A. Keyser -- W/NP22
Subject:        Changes to 3DVAR/OI/SSI-Data Preprocessor
                (February 17, 1998 Version -- UPDATE # 3)

The February 17, 1998 version of the data preprocessor program
(PREPDATA) was updated for the third time as a CRISIS.  UPDATE #3
was implemented on 1200 UTC 21 May 1998.  Except where noted, the
changes below affect all three versions, 3DVAR, OI, and SSI.

*********************  U P D A T E   # 3  ***********************

I.  GENERAL CHANGES

     1) Added processing of RTOVS data based on a new namelist
switch RTOVS (default is TRUE).  New external subroutines
W3RTVUNP and W3RTVEDS interface with RTOVS BUFR data dump file
and return either 40-level sounding/radiance reports or partial
NMCEDS format reports, respectively.  Added counts for rejected
TOVS/RTOVS in NMCEDS format processing, summarized in stdout
print at end of program.  [MAIN, SATEDS, SATBFR]

 
II.  OPERATIONAL CHANGES SPECIFIC TO A DATA TYPE

   A) CHANGES TO RADIOSONDE PROCESSING

     1) Fixed an error which resulted in certain tropopause winds
with speed of zero to NOT get flagged with q.m.=15 as they should
be.  This was occurring when Cat. 5 was a duplicate wind level
with a Cat. 3 level.  The flagging was moved from subroutine
GETUPA to STOROB to correct this problem. [MAIN, GETUPA, SMERGE]


   B) CHANGES TO RTOVS SOUNDING DATA PROCESSING

     1) 3DVAR, OI, CDAS: RTOVS is now processed in place of TOVS
(RTOVS=T).  For NMCEDS processing, RTOVS will sample 250km
retrievals by processing only every 4'th retrieval is reads from
the dump file (no filter flag information yet available in
RTOVS).  [The SSI, using only ozone from TOVS, will continue to
use TOVS instead of RTOVS (RTOVS=F)]. [DATACARDS]