[Met_help] PWAT verification with MET Tools
Thomas Schwitalla
Thomas.Schwitalla at uni-hohenheim.de
Wed Nov 18 09:16:27 MST 2009
John,
the command I use is:
./point_stat
/taifun/20070720_cops_WRF_sensitivity/assim/wrf_files/postprd/WRFPRS_2007072000_d01.000
20070720_pwat.nc PointStatConfig -v 10 >& log (attached)
Thomas
John Halley Gotway schrieb:
> Thomas,
>
> I'm thinking that you've made a mistake in how you're calling Point-Stat on the command line.
>
> Take a look at how you're calling it on the command line and make sure it matches the calling sequence:
> point_stat fcst_file obs_file config_file
>
> Based on the error, my guess is that you're passing the "obs_file" in the "config_file" spot.
>
> John
>
> Thomas Schwitalla wrote:
>
>> John,
>>
>> with
>>
>> fcst_field[] = [ "PWAT/L0" ];
>>
>> it works.
>> Concerning the times, I had a mistake in my original conversion program
>> which should be solved now....
>>
>> but now I get:
>>
>> config() -> syntax error in file "20070720_pwat.nc"
>>
>> line = 1
>>
>> econfig_column = 7
>>
>> text = "V8"
>>
>> CDF
>>
>>
>> Thanks again for your help!
>>
>> Thomas
>>
>>
>> John Halley Gotway schrieb:
>>
>>> Thomas,
>>>
>>> OK, sorry, my mistake. You need to use:
>>> fcst_field[] = [ "PWAT/L0" ];
>>>
>>> The "L0" says "give me a field with a level value of 0 and I don't
>>> care what type of level it is". When you say "Z0" the code looks at
>>> what type of level is in the GRIB file and only uses the one
>>> defined on vertical levels. But PWAT isn't defined on a vertical
>>> level - it's level type is the "entire atmosphere (considered as a
>>> single layer)".
>>>
>>> The reason why we have all these silly letters is to avoid conflicts.
>>> For example, other users have had temperature at 2-meters and 2 mb.
>>> Both records will have a level value of 2, but "Z2" will get
>>> you the first one, while "P2" will get you the second one. And if all
>>> else fails, you can always say "PWAT/R171" to explicitly give you GRIB
>>> record number 171 - which wgrib told us is the record
>>> number for PWAT in that file.
>>>
>>> I was able to get it to run using "PWAT/L0", but initially Point-Stat
>>> found no matched pairs. It looks like there a slight time offset
>>> that's causing the problem. This is a 1-hour forecast
>>> initialized at 2007072000 - so the valid time is 2007072001. I looked
>>> at the observations your using, and they range in time from
>>> 20070720_230700 to 20070720_235200.
>>>
>>> You're welcome to compare this forecast to these observations if you'd
>>> like, but you'll need to set the matching time window differently to
>>> do so. In the config file, you can set the "beg_ds" and
>>> "end_ds" parameters to define the matching time window in reference to
>>> the forecast time window. Alternatively, the "-valid_beg" and
>>> "-valid_end" command line options override the "beg_ds" and
>>> "end_ds" settings in the config file.
>>>
>>> Once I changed the time window, I was able to get matched pairs.
>>>
>>> Hope that helps.
>>>
>>> John
>>>
>>> Thomas Schwitalla wrote:
>>>
>>>
>>>> I uploaded the data on your ftp server, as one timestep is about
>>>> 100MB...
>>>>
>>>> Thanks again for your effort! Your reaction time is fantastic! 8-)
>>>>
>>>> Thomas
>>>>
>>>> John Halley Gotway schrieb:
>>>>
>>>>
>>>>> Thomas,
>>>>>
>>>>> Please send me a sample forecast file, a sample ASCII file, and the
>>>>> PointStatConfig file you're using. I'll take a look and see if I can
>>>>> figure it out.
>>>>>
>>>>> If the forecast file is pretty large, you could post those to our
>>>>> anonymous ftp site:
>>>>>
>>>>> ftp ftp.rap.ucar.edu
>>>>> username=anonymous
>>>>> password="your email address"
>>>>> cd incoming/irap/met_help/schwitalla_data
>>>>> put "your files, 1 at a time"
>>>>> bye
>>>>>
>>>>> Just let me know when you've posted the files.
>>>>>
>>>>> Thanks,
>>>>> John
>>>>>
>>>>> Thomas Schwitalla wrote:
>>>>>
>>>>>
>>>>>
>>>>>> John,
>>>>>>
>>>>>> when I try your suggestion, I got the following message:
>>>>>>
>>>>>> ERROR: process_grib_codes() -> no records matching GRIB code 54 with
>>>>>> level indicator of Z0 found in GRIB file:
>>>>>> /taifun/20070720_cops_WRF_sensitivity/assim/wrf_files/postprd/WRFPRS_2007072000_d01.002
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> "wgrib -v" on this file gives:
>>>>>>
>>>>>> 171:80565400:D=2007072001:PWAT:atmos col:kpds=54,200,0:1hr
>>>>>> fcst:winds in
>>>>>> grid direction:"Precipitable water [kg/m^2]
>>>>>>
>>>>>> A sample line of my ASCII file reads:
>>>>>>
>>>>>> ADPSFC 0007 20070720_233700 52.9480 12.3922 60.9550 54
>>>>>> -9999 60.9550 31.3000
>>>>>>
>>>>>> Now I am a bit confused...
>>>>>>
>>>>>> Thomas
>>>>>>
>>>>>> John Halley Gotway schrieb:
>>>>>>
>>>>>>
>>>>>>> Thomas,
>>>>>>>
>>>>>>> Just to be clear...
>>>>>>> (1) Your forecast from WPP of precipitable water is a value that's
>>>>>>> integrated over the whole column of air above each grid point.
>>>>>>> (2) Your point observations of precipitable water are the same - a
>>>>>>> value for the whole column of air above the observation point at the
>>>>>>> surface.
>>>>>>>
>>>>>>> If that's true, I'd set up the PointStatConfig file as follows:
>>>>>>> fcst_field[] = [ "PWAT/Z0" ];
>>>>>>> message_type[] = [ "ADPSFC" ];
>>>>>>>
>>>>>>> That means "give me the precipitable water field with a level
>>>>>>> value of
>>>>>>> 0", which is how's it's stored in your GRIB file. And verify against
>>>>>>> "surface" observations. When you call ASCII2NC, be sure to
>>>>>>> encode these PWAT observations using the "ADPSFC" message type.
>>>>>>>
>>>>>>> Give that a try and let me know if you have any problems.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> John
>>>>>>>
>>>>>>> Thomas Schwitalla wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> John,
>>>>>>>>
>>>>>>>> I want to verify WRF forecasts (postprocessed with WPP) with PWAT
>>>>>>>> data
>>>>>>>> from GPS stations. I already wrote it to NETCDF with ascii2nc but I
>>>>>>>> haven't figured out how to edit PointStatConfig that I can use
>>>>>>>> PWAT. My
>>>>>>>> problem is: What value to set for the level type/code as PWAT is an
>>>>>>>> integrated value?
>>>>>>>>
>>>>>>>> wgrib output looks as follows:
>>>>>>>>
>>>>>>>> PWAT kpds5=54 kpds6=200 kpds7=0 levels=(0,0) grid=255 atmos col 1hr
>>>>>>>> fcst:
>>>>>>>>
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>> Thomas
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>
>>>>>>
>>>>
>>>>
>>
--
*****************************************
*Thomas Schwitalla *
*Institute of Physics and Meteorology *
*University of Hohenheim *
*Garbenstrasse 30 *
*70599 Stuttgart *
*Germany *
*Tel.: +49 711 459 22154 *
*****************************************
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