[Met_help] point_stat in MET

Mon Apr 19 11:56:32 MDT 2010

Marlous,

OK, I think I've figured it out.  The problem is actually in your GRIB file.  The scanning mode flag in the Grid Description Section of your GRIB file is set to 0 when it should probably be set to 64.
 When MET reads your GRIB file, it thinks the lower boundary of your domain is 70 degrees N, when in fact that should be the upper boundary.

I ran this GRIB file through MODE and saw that it didn't plot the domain where it should be.

When I manually changed the scanning mode flag to 64, I saw two things:
- The plot MODE generated is now in the correct location on earth.
- The number of matched pairs in Point-Stat increased from 7 to 19,943.

You have two options...
(1) Fix how the GRIB files are being generated and set the scanning mode flag to 64.  This is Octet 28 of the Grid Description Section in GRIB
(http://www.nco.ncep.noaa.gov/pmb/docs/on388/tabled.html).  Try running: wgrib -V -GDS10 wrf_main_9km_eu_2010041406_25.grb

  Here's the output of that wgrib command:
  ----------------------------------------------------
  rec 2:212034:date 2010041405 DPT kpds5=17 kpds6=105 kpds7=2 levels=(0,2) grid=255 2 m above gnd 25hr fcst:
  DPT=Dew point temp. [K]
  timerange 10 P1 0 P2 25 TimeU 1  nx 240 ny 471 GDS grid 0 num_in_ave 0 missing 0
  center 7 subcenter 0 process 89 Table 2 scan: WE:NS winds(grid)
  latlon: lat  35.224000 to 70.004000 by 0.074000  nxny 113040
          long -11.850000 to 24.000000 by 0.150000, (240 x 471) scan 0 mode 136 bdsgrid 1
  GDS10(1..32)=
       1:   0   0  32   0 255   0   0 240   1 215   0 137 152 128  46  74 136   1  17 116
      21:   0  93 192   0 150   0  74   0   0   0   0   0
  min/max data 262.908 289.106  num bits 15  BDS_Ref 262908  DecScale 3 BinScale 0
  ----------------------------------------------------

  That 28th entry in the GDS section is 0 but should be 64.

(2) The second option is to modify the MET source code so that it ALWAYS uses a value of 64 instead of 0 for the scanning mode flag.  This is a short-term hack to address your immediate problem.  Copy
the attached file "read_grib.cc" into METv2.0/lib/vx_met_util/. and recompile MET.

Ultimately, it would be better to fix the generation of the GRIB file.

Hope that helps.

John

Marlous Jonker wrote:
> Hi John,
> 
> Here is the link again:
> 
> https://www.wetransfer.com/dl.php?code=3hAnj9Pu&hash=0761aeb719a21cdcdf4
> 4dde0bbc3f2f06cbd3d27a7af90ab8085ee08daec65549b04c70955cf1
> 
> I hope it works! Otherwise I'll have to try and zip the files.
> 
> Cheers,
> Marlous
> 
> 
> -----Oorspronkelijk bericht-----
> Van: John Halley Gotway [mailto:johnhg at ucar.edu] 
> Verzonden: vrijdag 16 april 2010 20:47
> Aan: Marlous Jonker
> CC: met_help
> Onderwerp: Re: point_stat in MET
> 
> Marlous,
> 
> I'd be happy to take a look, but unfortunately the link you sent didn't
> work for me.  When I pasted into the browser, it couldn't find it.
> 
> Could you instead post it to our anonymous ftp site:
> ftp ftp.rap.ucar.edu
> username = anonymous
> password = "your email address"
> cd incoming/irap/met_help/jonker_data
> put "your files"
> bye
> 
> Please try posting them there and I'll take a look.
> 
> Thanks,
> John
> 
> Marlous Jonker wrote:
>> Hi John!
>>
>>  
>>
>> How are you doing? Half a year ago I had a few questions about getting
>> started with MET using the sample data from the MET package. Nowadays
> I
>> am attempting to make an operational verification process with MET for
>> WRF and other mesoscale models. From this a new question arises.
>>
>>  
>>
>> When trying to run Point_stat with a WRF gribfile and ascii
> observation
>> file (converted to netcdf with MET), I find that Point_stat uses very
>> few matches pares: only seven (even when the grib file covers most of
>> Europe and the observation file contains over 136000 observations).
> When
>> trying to simplify the problem and using only one station (of which
> I'm
>> sure it's right in the middle of my domain: station 6260, de Bilt, The
>> Netherlands) Point_stat finds no matching pairs at all.
>>
>> Below you find the link to both the observation files (ascii and
>> netcdf), the config file and the WRF grib I used. They are too large
> to
>> send by e-mail.
>>
>>  
>>
>>
> https://www.wetransfer.com/dl.phpcode=3hAnj9Pu&hash=0761aeb719a21cdcdf44
>> dde0bbc3f2f06cbd3d27a7af90ab8085ee08daec65549b04c70955cf1
>>
>> I hope you can help me to find the problem and solution.
>>
>>  
>>
>> Thanks in advance,
>>
>>  
>>
>> Marlous Jonker
>>
>>  
>>
>> -------------------------------------------------------------------
>>
>>   Marlous Jonker
>>
>>   Meteorological Researcher
>>
>>   Meteo Consult BV, Wageningen, the Netherlands
>>
>>   Tel: +31 (0)317 399872
>>
>>   Email: M.Jonker at weer.nl
>>
>>   www: research.meteogroup.com
>>
>> -------------------------------------------------------------------
>>
>>  
>>
>>
>>
> 
> 
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