Re: WRF: Relative vorticity and Divergence

It looks like there is already a WRF function for computing absolute
vorticity. See

http://www.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/Examples/DIAGNOSTICS/wrf_pv.htm

Could you just use this and subtract the Coriolis factor at each grid
point (or modify the function wrf_avo to compute relative vorticity)? I
couldn't find the function but it needs map factors as input, so it has
likely accounted for the coordinate issue.

- Evelyn

Dennis Shea wrote:
> In order to use the suggested functions, you would have to interpolate
> the curvilinear WRF coordinates XLAT/XLONG to a regular [rectilinear]
> grid using:
>
> http://www.ncl.ucar.edu/Document/Functions/Built-in/rcm2rgrid.shtml
> or
>
> http://www.ncl.ucar.edu/Document/Functions/Contribute/rcm2rgrid_Wrap.shtml
>
>
> Then use the uv2dv_cfd & uv2vr_cfd functions.
>
> Finallay interpolate back to the original WRF coordinates
>
> http://www.ncl.ucar.edu/Document/Functions/Built-in/rgrid2rcm.shtml
>
> or
>
>
> http://www.ncl.ucar.edu/Document/Functions/Contributed/rgrid2rcm_Wrap.shtml
>
> ====
> Note:
> If the purpose is for deriving vorticity/divergence is "visual",
> then the above approach is probably adequate for both quantities.
> However, if the derived quantities are going to be used as the basis
> for further derivations, they should be used with extreme caution
> [in particular, divergence].
>
>
>
> On 04/18/2010 11:44 AM, Mateus Teixeira wrote:
>
>> Dear Sahidul,
>>
>> You can calculate relative vorticity and divergence with uv2vr_cfd and
>> uv2dv_cfd, respectively. Please take a look at
>>
>>
>> uv2dv_cfd -> for divergence
>> http://www.ncl.ucar.edu/Document/Functions/Built-in/uv2dv_cfd.shtml
>>
>> uv2vr_cfd -> for vorticity
>> http://www.ncl.ucar.edu/Document/Functions/Built-in/uv2vr_cfd.shtml
>>
>> Examples for Vorticity
>> http://www.ncl.ucar.edu/Applications/vort.shtml
>>
>>
>> I hope that it helps you.
>>
>> Best regards,
>>
>> Mateus
>>
>>
>> 2010/4/18 Sahidul <sahidul@gmail.com <mailto:sahidul@gmail.com>>
>>
>> NCL Users,
>>
>> We have WRF forecast files, saved in 1 hour interval having total 88
>> files. We want contour plot for "Relative Vorticity" and
>> "Divergence" every hour.
>>
>> Is there any function or Script for calculating "Relative Vorticity"
>> and "Divergence" ?
>>
>> Thanking you,
>>
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>>
>>
>>
>> --
>> Mateus da Silva Teixeira
>> Meteorologista
>> Instituto de Pesquisas Meteorológicas - IPMet
>> Universidade Estadual Paulista - UNESP
>> Av. Luis Edmundo Carrijo Coube, 14-01 - Cx. Postal 281 - CEP 17033-360
>> Bauru - SP - Brasil
>> Fone: +55 14 3103-6030 / fax: 3203-3649
>>
>> Registered Linux User #466740 (http://counter.li.org/)
>>
>>
>>
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>
>
>

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Received on Mon Apr 19 12:08:11 2010