January 18, 2002

MEMORANDUM TO:  Record
FROM:           Dennis A. Keyser -- NP22
Subject:        Changes to IBM-SP Data Preprocessor (PREPDATA)
                (February 17, 2000 Version -- UPDATE # 9)


The February 17, 2000 data preprocessor program (PREPDATA) was
updated for the ninth time.  UPDATE #9 was implemented on the
IBM-SP machine at 12Z on January 15, 2002.  Except where noted,
the changes below affect all five versions: ETA, AVN, FNL, RUC
and CDAS.

**************** I B M - S P   U P D A T E   # 9  ***************


I. GENERAL CHANGES

     1) Added new namelist switch IACFTH which provides an upper
altitude limit above which AIREP/PIREP (word 1), AMDAR/ASDAR
(word 2) and ACARS (word 4) reports are flagged (all variables)
with q.m. 15 (word 3 is reserved).  The default is 18000 meters
(approx. 75 mb) for AIREP/PIREP and AMDAR/ASDAR, and 16500 meters
(approximately 95 mb) for ACARS.  The default values are
currently used in all networks. [MAIN, GETC06, DATACARDS]


II. OERATIONAL CHANGES SPECIFIC TO A DATA TYPE

  A. CHANGES TO AIRCRAFT DATA PROCESSING

     1) All ACARS reports with altitude above 16500 meters
(approx. 95 mb) are now flagged (all variables) with q.m. 15 (see
I.1 above). [MAIN, GETC06]

     2) All AIREP/PIREP and AMDAR/ASDAR reports with altitude
above 18000 meters (approx. 75 mb) are now flagged (all
variables) with q.m. 15 (see I.1 above). [MAIN, GETC06]

     3) ACARS and RECCO reports with calculated dewpoint
temperature less than namelist value TDLIM (set to default of 215
K) now encode calculated dewpoint temperature (TDO), calculated
or reported specific humidity (QOB), and calculated virtual
temperature (TVO) in the PREPBUFR file, but set the moisture
quality marker (QQM) to 15 so these data will not be assimilated
by the analyses.  Prior to this, such levels set the dewpoint
temperature and specific humidity to missing, and set the virtual
temperature to the sensible temperature (TOB) value. [MAIN,
GETC06, FIZZ01]

     4) ETA only: ACARS moisture data (specific humidity) are no
longer unilaterally flagged with quality mark 15.  This change
allows these data to be considered by the verification codes. 
This is accomplished by changing namelist switch FLACMS from TRUE
to FALSE in the eta datacards. {The 3DVAR observational error for
ACARS moisture has been set to missing on all levels, so these
data will still not be assimilated by the 3DVAR analyses.}
[DATACARDS]


  B. CHANGES TO UPPER-AIR (RAOB, DROPWINSONDE) DATA PROCESSING

     1) Levels with reported dewpoint temperature less than
namelist value TDLIM (set to default of 215 K) now encode
dewpoint temperature (TDO), calculated specific humidity (QOB),
and calculated virtual temperature (TVO) in the PREPBUFR file,
but set the moisture quality marker (QQM) to 15 so these data
will not be assimilated by the analyses.  Prior to this, such
levels set the dewpoint temperature and specific humidity to
missing, and set the virtual temperature to the sensible
temperature (TOB) value. [MAIN, SMERGE, FIZZ01]


  C. CHANGES TO SURFACE DATA PROCESSING

     1) Levels with reported dewpoint temperature less than
namelist value TDLIM (set to default of 215 K - OF COURSE SHOULD
ALMOST NEVER OCCUR AT SURFACE!) now encode dewpoint temperature
(TDO), calculated specific humidity (QOB), and calculated virtual
temperature (TVO) in the PREPBUFR file, but set the moisture
quality marker (QQM) to 15 so these data will not be assimilated
by the analyses.  Prior to this, such levels set the dewpoint
temperature and specific humidity to missing, and set the virtual
temperature to the sensible temperature (TOB) value. [MAIN,
SFCDTA, FIZZ01]

  D. CHANGES TO quikSCAT SCATTEROMETER WIND DATA PROCESSING

     1) AVN, FNL only: quikSCAT scatterometer wind reports are
now encoded in the PREPBUFR file under report type 285 and will
be assimilated by the Global SSI analyses.  This is accomplished
by changing namelist switch JPSSMI from 6*9999 to 6*0 in the avn
and fnl datacards. [DATACARDS]