[Met_help] met and WRF/ARW

[John Halley Gotway]

Joe,

When running WPP, you can specify the grid onto which you'd like the model
data interpolated.  For more detail than that, let me refer you to:

(1) Chapter 7 of the WRF-NMM users guide which discusses WPP:
http://www.dtcenter.org/wrf-nmm/users/docs/user_guide/V3/users_guide_nmm_chap1-7.pdf

(2) The WRF tutorial slides on WPP:
http://www.mmm.ucar.edu/wrf/users/tutorial/201001/2010jan_wpp_joint_tutorial.pdf

When running WPP, you are able to control the levels at which variables
are output by editing the file "wrf_cntrl.parm".  If the vertical levels
available via WPP are not sufficient for your needs, I'd suggest sending a
question to wrfhelp at ucar.edu to find out if there are any work-arounds.

Thanks,
John

> Hi John,
>
> Is the horizontal interpolation to T points? And when you say interpolates
> to pressure levels, does that mean the ones you specify in
> namelist.ARWpost? The reason I ask is that for our work we have very hi
> resolution at the surface 10-20m deltaz throughout the PBL. We validate
> and verify using sodar/lidar data with a similar delta Z. Thanks for your
> time.
>
> Take care,
> Joe
>
> Dr. Joseph L. Eastman
> Senior Atmospheric Scientist
> WindLogics Inc.
> 201 4th St NW
> Grand Rapids, MN
> 55744
>
> c - 410.279.9702
> w - 651.556.4297
> jeastman at windlogics.com
>
>
>
> -----Original Message-----
> From: met_help-bounces at mailman.ucar.edu
> [mailto:met_help-bounces at mailman.ucar.edu] On Behalf Of John Halley Gotway
> Sent: Tuesday, February 16, 2010 11:52 AM
> To: Julien Pergaud
> Cc: met_help at ucar.edu
> Subject: Re: [Met_help] met and WRF/ARW
>
> Julien,
>
> Yes, we highly recommend running your WRF output through WPP prior to
> using it in MET.  Running it through WPP does three things:
>
> (1) Interpolates in the horizontal from the staggered model grid to a
> regular grid.
> (2) Interpolates in the vertical from eta levels to pressure levels.  The
> MET Point-Stat tool does matching in the vertical using pressure levels,
> not eta levels, since observations are typically
> reported at pressure levels.
> (3) Derives several fields, including temperature from the ARW model
> output.
>
> Try switching your WRF output format back to NetCDF and rerunning it
> through WPP.  I mentioned this to the primary WPP support person here, and
> she guessed that since you're running ARW, you probably
> have multiple output times in each NetCDF output file.  Because of that,
> you'll need to run the WPPV3.1/scripts/run_wrfpost_frames script.  That
> will read multiple times from the ARW NetCDF files and
> write them out to separate GRIB output files.
>
> Please give that a shot, and if you continue to experience trouble running
> WPP, send an email to wrfhelp at ucar.edu.
>
> Thanks, and once you get up and running, let us know if any more questions
> arise in your use of MET.
>
> John Halley Gotway
> johnhg at ucar.edu
>
> Julien Pergaud wrote:
>> Hello
>>
>> I have some questions abous the use of MET with the version ARW of WRF.
>> First, as explained in the tutorial, i have used WPP to transform nectdf
>> output
>> in grib.
>> But, if the first files (first time of the simulation) was tranformed in
>> grib
>> without problem, it was not the case for other files (other times).
>> So, i have decided to use the possibility of WRF/ARW to create as output
>> grib
>> files directly.
>> When i want to use the capability of MET to deal with UPA data, i meet
>> some
>> problems.
>> First, in grib file obtained directly from WRF/ARW, levels are defined
>> as ETA
>> levels and not pressure levels.
>>   - How can i read eta levels with MET? Is it possible?
>>   - TMP can be extract at different level using LNNN or RNNN. Are L and
>> R linked
>> to eta levels. For example, L1.2 doesn't run while L2.5 runs.
>>    - This remark is linked to the previous. Temperature is an output
>> variable of
>> WRF only for 2m level. WRF provides potentiel temperature at the
>> different
>> vertical levels and not TMP.
>>      Is MET able to compute temperature from the different variable of
>> WRF
>> (potential temperature and pressure)? If not what is TMP/L2.5
>>      if i put POT as a variable name in the PointStat config file, MET
>>
>> I have checked the only grib file coming from WPP and this last one
>> contains TMP
>> at different vertical pressure levels.  So WPP seems to compute
>> temperature from
>> potential temperature.
>> Do you think it's better to use WPP. If yes, how can i solve my problem
>> with WPP.
>> Thank you in advance for your answer.
>>
>> Julien
>> --
>>
>> NUMTECH <http://www.numtech.fr>       Julien PERGAUD
>> Ingénieur d'études et de recherche / SO
>> 6, allée Alan Turing - BP 30242 - Parc Technologique de la Pardieu
>> 63175 AUBIERE Cedex - FRANCE
>> Tél: 33 (0)4 73.28.75.95 - Fax: 33 (0)4.73.28.75.99
>> Web: http://www.numtech.fr
>>
>>
>>
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>>
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