[Datastream #HJY-878726]: NDFD files #197 and #255

Hi Kevin,

re:
> The process ID does appear in the NAM/NMM files LDM string, though. 84
> is the process ID for NAM, 89 is for NMM, according to
> http://www.nco.ncep.noaa.gov/pmb/docs/on388/tablea.html
> I do see the #242 and #255 which are the GRID definition ID's after
> that, like you said, though.

Thinking that the code sequence in our NOAAPort package was the same
as in the gribinsert package (the package that processes model output
for inclusion in the CONDUIT datastream), I based yesterday's answer
on what I saw in gribinsert.  This turns out to have been a mistake; sorry.

Looking through the NOAAPort code, I found the following code snippit
(in grib2name.c):

   if ( curr_g2.gfld->griddef == 0 )
      grid_id = decode_g2gnum ( curr_g2.gfld );
   else
      grid_id = curr_g2.gfld->griddef;

curr_g2.gfld->griddef is set as follows in g2/g2_getfld.c:

//        gfld->griddef = Source of grid definition (see Code Table 3.0)
//                      0 - Specified in Code table 3.1
//                      1 - Predetermined grid Defined by originating centre

So, if the value for gfld->griddef (which becomes curr_g2.gfld->griddef in 
grid2name.c) is zero, it is defined by decode_g2gnum, which seems to set
the value based on the projection of the grid.

> NGRID 28926020  MUSZ85 KWBE 271200
> !grib2/ncep/*NAM_84*/#242/201109271200F081/UREL/850 hPa PRES
> NGRID 28926128  LECL98 KWBE 271200
> !grib2/ncep/*NMM_89*/#255/201109271200F084/P06M/0 - NONE

re:
> Also, I have some confusion with these grids
> CONDUIT 001  data/ndfd/YEUZ98_KWBN_271547.grib2
> !grib2/nwstg/NWS_0/#000/201109271600F005/TMPK/0 - NONE! 000001
> 
> Looks like NWS model 0 and grid definition ID 0. I was able to determine
> that these are on the same grid definitions as the 197 NDFD files.
> Shouldn't these be #197 as well then?

I am not sure (I didn't write the original code, and the author no longer
works at Unidata).  A careful review of the code would need to be made
to see if the gribinsert code needs to be changed to match the NOAAPort
code or vice versa.

re:
> Unlike GRIB1, the geographic ID (or grid definition ID) is not
> identified in GRIB2 files, but if you know what it is, you can match it
> up with the definitions at
> http://www.nco.ncep.noaa.gov/pmb/docs/on388/tableb.html
> But the process ID is actually in the GRIB2 files, so that's why I am
> interested in defining GRIB files with it.

Yes, but this is not done at the moment.  Requesting such a change can
be made, of course, but its priority will likely be pretty low.


Cheers,

Tom
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Ticket Details
===================
Ticket ID: HJY-878726
Department: Support Datastream
Priority: Normal
Status: Closed