[Met_help] point stat & ascii2nc

[John Halley Gotway]

Leela,

Glad it worked.  We'll make a note to include it in the next version of the user's guide.

Feel free to write with any more issues or questions.

Thanks,

John

Watson.Leela wrote:
> Thanks, John - it worked.
> 
> I think that performing the matching by message type is sufficient
> enough. The only thing that I would request is that the user's guide
> mention exactly what you stated in your email below - how the matching
> is performed and what the message type should be for comparing surface
> obs to forecasts at the surface.
> 
> Leela
> 
> -----Original Message-----
> From: John Halley Gotway [mailto:johnhg at rap.ucar.edu] 
> Sent: Tuesday, September 09, 2008 4:41 PM
> To: Watson.Leela
> Cc: met_help
> Subject: Re: [Met_help] point stat & ascii2nc
> 
> Leela,
> 
> Actually, after looking at your ASCII observations, I have a guess as to
> what's going on.  So you probably don't need to send the GRIB file
> anyway.
> 
> Even though this may not be strictly correct, in your ASCII
> observations, please try replacing "MSONET" with "ADPSFC" and rerunning
> ASCII2NC and Point-Stat.  I'm guessing that will fix the problem.
> 
> Here's what I believe is going on...  In Point-Stat, observations are
> typically matched to forecast fields based on pressure level.  So for
> example, if you're verifying temperature between 800mb and
> 500mb, it'll look at the pressure level of each observation and match
> them to the forecast if they fall in that range.  However, that doesn't
> work for matching observations to forecasts at the
> surface.  So in MET, we adopted the method that NCEP's chosen which is
> to simply match up based on message type.  When verifying fields at the
> surface (2m temp or 10m winds), Point-Stat only matches
> "surface" observations of type ADPSFC or SFCSHP.  Your MSONET
> observations aren't being matched because they're not being included as
> a surface observation.  So all observations of type ADPSFC or
> SFCSHP are assumed to be at the surface and are matched to forecasts at
> the surface.
> 
> As a user, I'm wondering, what's your opinion?  How would you like to
> see the matching performed for surface observations?  Is doing it by
> message type sufficient, or would you like to see us do
> something more sophisticated like comparing the elevation of the
> observation to the elevation at that lat/lon point?
> 
> Thanks,
> John
> 
> 
> Watson.Leela wrote:
>> John,
>>
>> I cannot send the ARW GRIB file - I keep getting an email back saying
>> 'Message Refused: Exceeded Message Size Threshold'. Is there some
> other
>> way that I can get the GRIB file to you? The file size is 16MB. I can
>> zip it, but it is still large - 13MB.
>>
>> Leela
>>
>> -----Original Message-----
>> From: John Halley Gotway [mailto:johnhg at rap.ucar.edu] 
>> Sent: Tuesday, September 09, 2008 2:41 PM
>> To: Watson.Leela
>> Cc: met_help at ucar.edu
>> Subject: Re: [Met_help] point stat & ascii2nc
>>
>> Leela,
>>
>> It would probably be easiest if you could send me the sample data that
>> you're using.  I'll try running it here to see if I can figure out
>> what's going on.
>>
>> Please send me the following:
>> (1) The ASCII input file to the ASCII2NC tool.
>> (2) Your NetCDF output file from ASCII2NC.
>> (3) The forecast file containing the 2m temp field from ARW.
>> (4) The configuration file that you're using when running the
> Point-Stat
>> tool.
>>
>> Thanks,
>> John Halley-Gotway
>> johnhg at ucar.edu
>>
>> Watson.Leela wrote:
>>> I am currently trying to use MET to verify 2m temperatures from ARW
>>> forecasts with local observation data available in ASCII format. I
>>> reformatted my observations to fit the format identified in the MET
>>> documentation for the ASCII2NC tool. My observations cover a domain
> of
>>> approximately 20km x 20km and there are only 12 of them. The grid
>>> spacing of the ARW output is 1km. When I run the point_stat tool I
>>> receive the following message indicating that there are no matching
>>> pairs:
>>>
>>>  
>>>
>>> Grib Record Index = 11
>>>
>>> Initialization time = 1201683600
>>>
>>> Valid time = 1201683600
>>>
>>> Accumulation time = 0
>>>
>>> Grib Record (min, max) = (229.37726, 291.74725)
>>>
>>>  
>>>
>>> ----------------------------------------
>>>
>>> Processing 12 observations from 12 PrepBufr messages...
>>>
>>> For Grib Field TMP at Z2 for observation type MSONET, over region
>> FULL,
>>> for interpolation method DW_MEAN(3), found 0 pairs.
>>>
>>>  
>>>
>>> I also noticed that when I ran the point_stat test script using the
>>> sample forecast and ascii data, it also produced similar errors for
>> the
>>> 10m UGRD and VGRD values:
>>>
>>>  
>>>
>>> For Grib Field UGRD at Z10 for observation type ADPUPA, over region
>>> DTC165, for interpolation method UW_MEAN(1), found 0 pairs.
>>>
>>> Etc...
>>>
>>>  
>>>
>>> I am confused as to how there can be no matching pairs when the
>>> observation point MUST fall between 4 grid points...?? Or maybe I am
>>> misunderstanding what the output message is saying. Any help would be
>>> appreciated!
>>>
>>>  
>>>
>>> Leela Watson
>>>
>>>  
>>>
>>> *********************************************************
>>>
>>> Leela R. Watson, Meteorologist
>>>
>>> ENSCO, Inc. / Applied Meteorology Unit
>>>
>>> 1980 N. Atlantic Ave., Suite 230
>>>
>>> Cocoa Beach, FL 32931
>>>
>>> Voice: (321) 853-8264
>>>
>>> Fax: (321) 853-8415
>>>
>>> Email: watson.leela at ensco.com
>>>
>>>  
>>>
>>>
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