[Met_help] verifying 2m temperaures with PointStat

[John Halley Gotway]

Joe,

I have heard of a similar concern from another user - not with temperature but with 10 meter winds.  In his case, it turned out that while he we was requesting 10 meter winds, the MET code was
incorrectly retrieving 10mb winds and using those!

In METv1.1, we're not matching the GRIB records as closely as we should.  Specifically, METv1.1 is ignoring the "Z" part of the "TMP/Z2" and just looking for a temperature record with a level value of
2.  I've fixed this problem for the next version of MET, METv2.0 in February.  But the fix touched several files so it wasn't put out as a fix for METv1.1.  Instead, there's a pretty simple workaround.

But first, let try to determine if you're in this situation.  Please try the following:
(1) Run the same point-stat command but with the "-v 3" option to turn on more logging.
(2) Look for the line "Grib Record Index ="... actually look for the second time that shows up.  The first time will just say "Grib Record Index = 1".
(3) Next run a "wgrib" command to find out which record we actually want to use in Point-Stat:
    wgrib FORECAST_FILE_NAME | grep TMP
(4) Find the temperature record in the wgrib output that says "2 m above gnd"
(5) Look at the index number for that record at the beginning of the line.

Does the index number for that record in the wgrib output match the index number for the record Point-Stat is using?

If not, then we've found the problem.  Just let me know, and I can help you with a work-around.

If they do match, then maybe something else is going on here.  If they match, please go ahead and send me some sample data:
(1) a sample forecast file
(2) the corresponding observation file (output of PB2NC)
(3) the Point-Stat config file you're using

And I'll look into it some more.

Thanks,
John Halley-Gotway
johnhg at ucar.edu

Joe Olson wrote:
> I'm trying to verify 2m temps output from WRF-ARW v3.0 and using METv1.1
> (PointStat).
> 
> First, I have performed the following to prepare the prepbufr:
> 
> 1) cwordsh block prepbufr_file prepbufr_file.blk
> 2) Converted Prepbufr to netcdf:
>         /METdir/bin/pb2nc prepbufr_file.blk prepbufr.ncdf
> /METconfigdir/PB2NCConfig
> 
> So far, this seems to work fine, since I have successfully used this
> file to verify upper-level temperatures...
> 
> Then, convert wrfouts (netcdf) to an A-grid (grib)
> 3) run_wrfpost
>     This outputs my wrfprs_d01.XX file.
>      In the wrf_cntrl.parm configuration file, I made sure to specify
> various forms of temperatures:
> 
>  (SHELTER TEMPERATURE ) SCAL=( 5.0)
>  L=(10000 00000 00000 00000 00000 00000 00000 00000 00000 00000 00000
> 00000 00000 00000)
>  (TEMP ON PRESS SFCS  ) SCAL=( 4.0)
>  L=(11111 11111 11111 11111 11111 11111 11111 11111 11111 10000 00000
> 00000 00000 00000)
> etc...
> 
> Then, when running PointStat with the output from (2) and (3) and using
> the following edits to the config file:
> 
> vx_grib_code[] = [ "TMP/Z2"];
> thresholds[] = [ "gt0"];
> message_type[] = [ "ADPSFC", "SFCSHP" ];
> 
> I get the requested output, but looking at the mpr file, the model
> forecast is way too cold (229-233 K) while the observations seem correct
> (270-278 K)
> :
> 
>     TOTAL INDEX OBS_LAT OBS_LON OBS_LVL    OBS_ELV     FCST    OBS CLIMO
> 1     286     1   58.68 -156.65   989.3   14.98281 232.3029 277.05 -9999
> 2     286     2   59.75 -154.92   995.2   49.12878 233.0589 275.95 -9999
> 3     286     3   57.75 -152.50   997.9   33.93378 232.8184 278.15 -9999
> 4     286     4   59.52 -139.67  1026.3    9.02245 230.9946 272.55 -9999
> 5     286     5   58.37 -134.58  1029.5    6.98383 230.5191 270.95 -9999
> 6     286     6   62.30 -150.10  1004.5  109.13992 233.0715 269.25 -9999
> 7     286     7   55.13 -131.58  1031.8    0.00000 230.0803 277.15 -9999
> 8     286     8   55.13 -131.58  1031.8    0.00000 230.0803 276.15 -9999
> 9     286     9   55.35 -131.70  1027.3   28.94379 230.0819 275.35 -9999
> 10    286    10   56.97 -133.95  1031.5    0.00000 229.8285 274.15 -9999
> 11    286    11   56.97 -133.95  1031.2    0.00000 229.8285 273.15 -9999
> etc....
> 
> Has anyone seen a problem like this? Are there any other steps I need to
> consider?
> 
> -joe
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