November 6, 1997

MEMORANDUM TO:  Record
FROM:           Dennis A. Keyser -- W/NP22
Subject:        Changes to OI/SSI-Data Preprocessor
                (May 1, 1997 Version -- UPDATE # 5)

The May 1, 1997 version of the data preprocessor program
(PREPDATA) was updated for a fifth time.  UPDATE #5 was
implemented on 1200 UTC 10 September 1997.  All changes now
affect only OBUFR = TRUE switch.  Except where noted, the changes
below affect both the GLOBAL and RGL/ETA models. PREPDATA now
exclusively uses JBUFR file input.

*********************  U P D A T E   # 5  ***********************

I.  GENERAL CHANGES

     1) This program was compiled to link in the updated BUFRLIB
library.  The BUFRLIB was recompiled without the degugging option
(-ez) turned on.  This should speed up computation time.


II. NON-OPERATIONAL (BUT SOON-TO-BE) CHANGES

A. CHANGES IN THE PROCESSING OF GOES SOUNDING DATA

     1) Corrects for situation when calculated top layer
precipitable water (TOTAL minus sum of bottom 3 layers) is
negative.  This occurs in two ways:
        - lots of retreivals with small negative (magnitude 0.1
mm) top layer precipitable water occur due to round-off error in
the JBUFR file storage - these are set to zero (actually any
where magnitude is less than 1.0 mm)
        - occasionally a top layer with a large negative
(magnitude greater than 1.0 mm) precipitable water is observed
(reasons unknown) - these retrievals are tossed