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20020311: gribdec.k decoding of AVN WAFS 1x1 degree grids



>From: "Hoeth, Brian" <address@hidden>
>Organization:  JSFC
>Keywords:  200202211951.g1LJpex01567 gribdec.k XCD

Brian,

>I've attached a sample GRIB file (it's the 00Z AVN 1x1 degree resolution
>(AVN WAFS) 0 hr fcst file from today).
>
>Let me know how your decoder handles it.

OK.  I ran the version of gribdec.k from my new gribdec.tar.Z package
and almost all of the grids seemed to decoded correctly.

Here is an example snippit of the ones that seemed to decode OK:

GRDLIST MYDATA/GRIDS.7010 NUM=ALL
Dataset position 7010   Directory Title=
PAR    LEVEL       DAY        TIME    SRC FHOUR     FDAY       FTIME  GRID  PRO
---- --------- ------------ -------- ---- ----- ------------ -------- ----- ----
Z    1000 MB   11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00     1 MERC
Z     975 MB   11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00     2 MERC
Z     950 MB   11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00     3 MERC
 ...

and here are the GRDLIST entries for the ones that were not:

 ...

Z    TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   245 UNKN
RH   TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   246 UNKN
 ...

SOLW TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   254 UNKN
SOLW TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   255 UNKN
T    TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   256 UNKN
T    TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   257 UNKN
 ...

TCVR TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   264 UNKN
P    TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   265 UNKN
P    TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   266 UNKN

In all, 272 grib messages were decoded, and 9 of them had UNKN projections.
The rest had the expected MERC projection.

I will have to investigate why the projection for these grids got set to
be UNKN since they all are grid 3 grids:

GRDLIST MYDATA/GRIDS.7010 GRID=245 246 FORM=ALL
Dataset position 7010   Directory Title=

PAR    LEVEL       DAY        TIME    SRC FHOUR     FDAY       FTIME  GRID  PRO
---- --------- ------------ -------- ---- ----- ------------ -------- ----- ----
Z    TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   245 UNKN
Total pts= 10512 Num rows=  73  Num columns= 144    received:  2002070 174833Z
Geopotential height
GRIB ID numbers: Geographic =  3; PAR =  7; Model ID = 81; Level type =204
Units of gridded variable are GPM  Scale of variable is:   2
PAR    LEVEL       DAY        TIME    SRC FHOUR     FDAY       FTIME  GRID  PRO
---- --------- ------------ -------- ---- ----- ------------ -------- ----- ----
RH   TRO       11 MAR 02070 00:00:00  AVN     0 11 MAR 02070 00:00:00   246 UNKN
Total pts= 10512 Num rows=  73  Num columns= 144    received:  2002070 174833Z
Relative humidity
GRIB ID numbers: Geographic =  3; PAR = 52; Model ID = 81; Level type =204
Units of gridded variable are %    Scale of variable is:   2
Number of grids listed = 2

I did contour plots of some of the grids that decode correctly, and
they look good.  An example of the first grid, 1000 mb Z can be seen
in:

http://www.unidata.ucar.edu/staff/tom/gifs/WAFS1000mbZ.gif

Again, I will need to look closely to see why 9 of the grids navigation
did not decode correctly and fix whatever is wrong (if there is something
wrong).

Tom


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