[Wrf-users] Re: Wrf-users Digest, Vol 29, Issue 5

[WRF Help]

T2m is a diagnostic variable. WRF-Var procedure doesn't  change it  
directly irrespective of temperature obs location.

wrfhelp

On Jan 5, 2007, at 12:00 PM, wrf-users-request at ucar.edu wrote:

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>    1. Re: Re: Wrf-users Digest, Vol 29, Issue 1 (Don Morton)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 4 Jan 2007 22:04:46 +0000
> From: "Don Morton" <Don.Morton at umontana.edu>
> Subject: Re: [Wrf-users] Re: Wrf-users Digest, Vol 29, Issue 1
> To: wrf-users at ucar.edu
> Message-ID:
> 	<237e74280701041404o229a64e8mabcf97f5b595b26b at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Thank you all, for those who had the patience to see me
> through my moments of confusion!  I think that, indeed,
> I was getting small differences, all along.  See below:
>
> On 1/3/07, WRF Help <wrfhelp at ucar.edu> wrote:
>> Best way to do single obs test in WRF-Var is to activate
>> "pseudo_ob_nl" namelist options.
>
> I was a little reluctant to go off in this direction because
> the ultimate goal is to ingest a number of obs (like the
> rest of you) in a real-time fashion, so I wanted to start
> by ingesting a single obs in the "normal way."
>
>> After successfully running WRF-Var, plot analysis increments
>> (analysis-background) to see how this single observation changed the
>> initial background (FG) field at different levels. With this setting
>> maximum increments is expected at level 10.
>
> This statement is what grabbed my attention, and I decided to use
> IDV to view the differences, and it showed a very small difference  
> field
> at level 0.942, on the order of something like 1.0E-1 or maybe even  
> 1.0E-2.
> It shows up as a rough circle centered right at my point of  
> application.  At the
> lowest level, it shows no difference.
>
> In the following, I'm speaking with some uncertainty (I'm the computer
> scientist who pretends to understand this stuff), so I'd be  
> appreciative if
> someone could correct or verify:
>
> I had intended to apply my temperature perturbation at the surface,  
> so in my
> little_r file specified an obs height of 16.2m and -888888 for the  
> pressure:
>
>             70.20100          -148.47100PASC
>          Deadhorse                               FM-12 SYNOP
>                   ASOS
> 16.20000         1         0         0         0         0         F
>       F         F   -888888   -888888      20061226180000-888888.00000
>      0-888888.00000      0-888888.00000      0-888888.00000
> 0-888888.00000      0-888888.00000      0-888888.00000
> 0-888888.00000      0-888888.00000      0-888888.00000
> 0-888888.00000      0-888888.00000      0-888888.00000      0
> -888888.00000      0     16.20000      0    245.00000
> 0-888888.00000      0-888888.00000      0-888888.00000
> 0-888888.00000      0-888888.00000      0-888888.00000
> 0-888888.00000      0
> -777777.00000      0-777777.00000      0-888888.00000
> 0-888888.00000      0-888888.00000      0-888888.00000
> 0-888888.00000      0-888888.00000      0-888888.00000
> 0-888888.00000      0
>       0      0      0
>
> It "appears" that 3dvar_obs.exe tried to translate this height to a
> pressure level,
> as the data portion of obs_gts.3dvar showed a pressure of 998.15mb:
>
> FM-12 SYNOP  2006-12-26_18:00:00 Deadhorse
>         1      70.201               -148.471                 16.200
>              PASC
>  -888888.000 -88 200.00 -888888.000 -88  0.200
>    99815.000  -5 100.00 -888888.000 -88   1.10 -888888.000 -88   5.00
>                16.200   0   6.00     245.000   0   2.00 -888888.000
> -11   2.00            -888888.000 -11  10.00
>
>
> The PSFC field in my background was showing a pressure of about
> 1002.5mb, so I'm
> guessing that since obs_gts.3dvar was showing the obs at 998mb, the  
> obs was
> actually being applied roughly 100 ft above the surface??  So, here I
> was, trying
> to look for changes in my T2 variable (2m temperature) and finding  
> nothing.
>
> Thanks again to those who offered insight.  It's an interesting  
> area, and now
> I'll move on ingesting multiple obs (eventually COSMIC data).
>
> Don
>
> -- 
> Don Morton
> Department of Computer Science
> The University of Montana - Missoula
> http://www.cs.umt.edu/~morton/
>
>
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> End of Wrf-users Digest, Vol 29, Issue 5
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>