[gradsusr] New GFS accumulated precipitation variable

[Wesley Ebisuzaki - NOAA Federal]

Hi,

There is a little information under "The new GFS forecast files"

    https://www.cpc.ncep.noaa.gov/products/wesley/wgrib2/ncep_norm.html

If you want a ctl file for GFS file and want to have different variable
names
for two APCP fields, you have to use alt_g2ctl/alt_gmp with the -0t option.

    https://www.cpc.ncep.noaa.gov/products/wesley/alt_g2ctl_gmp.html

alt_g2ctl -0t GFS.in >GFS.ctl
alt_gmp GFS.ctl

Templating the original files is a harder problem.

Wesley


On Thu, Jun 13, 2019 at 9:53 AM Adams, Jennifer M. (GSFC-610.2)[ADNET
SYSTEMS INC] <jennifer.m.adams at nasa.gov> wrote:

> Hi, Everyone –
>
> I’m sure many of you are aware of the changes to the GFS that went
> operational with yesterday’s 12Z run. In the new data files, there are two
> records for accumulated precipitation that look identical except for the
> beginning-of-accumulation information. Here is what the wgrib2 output looks
> like for the APCP variable in the 12hr forecast and 15hr forecast files:
>
>
>
> # wgrib2 gfs.t12z.pgrb2.0p25.f012 | grep APCP
>
> 449:248062227:d=2019061212:APCP:surface:6-12 hour acc fcst:
>
> 450:248429916:d=2019061212:APCP:surface:0-12 hour acc fcst:
>
>
>
> # wgrib2 gfs.t12z.pgrb2.0p25.f015 | grep APCP
>
> 449:246395924:d=2019061212:APCP:surface:12-15 hour acc fcst:
>
> 450:246700803:d=2019061212:APCP:surface:0-15 hour acc fcst:
>
>
>
> The variable in record #449 is the ‘old’ version, with different
> accumulation periods depending on the forecast hour. The variable in record
> 450 has the ‘new’ version, with accumulations from the beginning of the
> forecast. There is no way to distinguish between these two based on the
> grib2 codes in a descriptor file. Here’s what I use:
>
>
>
> p           0,1,0            0,1,8,1    Total Accumulated Precipitation
> [kg/m2]
>
>
>
> As gribmap examines the records in the grib file to look for matches in
> the descriptor file, it will find record 449 and index that position for
> the variable p. Then it will find record 450 and overwrite the index for
> the variable p with the new position. So, as long as the ‘new’ version of
> APCP appears after the ‘old’ version in the grib file, gribmap will index
> the ‘new’ records, and you can work with the precip data assuming the new
> accumulation standards. NCEP says that the ‘old’ variables will be phased
> out in the near future, so there’s no point in trying to match with the old
> style records.
>
>
>
> In many ways, the new standard is easier to deal with, although those of
> us who have written a boatload of scripts to work around the awkwardness of
> the old standard have some revisions to do. I am working on modifications
> to the scripts behind the maps at wxmaps.org and wx.gmu.edu.  I hope to
> have things looking right by the end of the week.
>
>
>
> Jennifer
>
>
>
> --
> Jennifer Miletta Adams
> ADNET Systems, Inc.
> NASA/GSFC, Code 610.2
>
> Building 32, Room S159
> (301) 614-6070
>
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
>
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