20020327: About This National Mosaic Radar Image (cont.)

>From:  "Batson, Bryan" <address@hidden>
>Organization:  JSFC
>Keywords:  200203201846.g2KIk1a20211 NWS RCM composite

Bryan, et. al.,

Last week I made the following comment about XCD being able to decode
the Radar Coded Message (RCM) grib messages in NOAAPORT:

>I believe that XCD already supports decoding of this product.  At least,
>I have been filing the GRIB messages using our distribution of the XCD 
>GRIB data monitor, dmgrid.pgm, for quite some time.  Also, I don't think
>that any of the changes I may have made to dmgrid.pgm would affect the
>decoding of the RCM composite.

Well, I _did_ make a change that probably _did_ affect the decoding of
the RCM composites.  The change I made (that you can implement quickly)
is to add an entry for the RCM in the grib table gbtbpds001.av1:

 ...
#   Last Modified: 09/15/93 (jsp)
#                  20000518 - Added Radar Coded Message entry
 ...
000 | Radar Coded Message                                                | RCM

If you want to give this mod a try, you should:

1) edit the copy of gbtbpds001.av1 that is being used by your XCD DMGRID
   data monitor

2) stop and restart DMGRID so that it will reread this table

I will be interested if any of you do this, and what your results are.
Your GRDLIST listing for the RCM grids should look something like:

GRDLIST RTGRIDS/MISC
 ...
RSPC SFC       28 MAR 02087 00:14:00  RCM     0 28 MAR 02087 00:14:00    27 PS
 ...

GRDLIST RTGRIDS/MISC.7 GRID=27 FORM=ALL

Dataset position 7      Directory Title= Misc. Grids for 28 MAR 2002
PAR    LEVEL       DAY        TIME    SRC FHOUR     FDAY       FTIME  GRID  PRO
---- --------- ------------ -------- ---- ----- ------------ -------- ----- ----
RSPC SFC       28 MAR 02087 00:14:00  RCM     0 28 MAR 02087 00:14:00    27 PS
Total pts=165600 Num rows= 360  Num columns= 460    received:  2002087 003959Z
Radar spectra (1), Time difference with         0  HHHMMSS data
GRIB ID numbers: Geographic =255; PAR = 21; Level type =  1
Units of gridded variable are x    Scale of variable is:   2
Polar Stereographic Projection
Row num of pole= -279.90  Col num of pole=  160.97  Col spacing (m)= 11906.0
Standard Latitudes=   60.00     60.00   Standard Longitude=  105.00
Number of grids listed = 1
GRDLIST - done

FYI, I just updated gbtbpds001.av1 in the SSEC XCD CVS repository.  I
added numerous fields that bring the table up to GRIB Edition 1 (FM92)
11/30/01 for originating center 7 values AND removed all of the entries
that would result in incorrect labeling of some fields as having ECMWF
as their SRC.

Tom