Re: tips to unstagger data from WRF

Using either ARW or NMM, to get 700 mb data you do have to convert to
pressure levels and destagger. Your logic looks correct. I've not
tried this (yet) at various levels, since I'm focusing on the surface
but I'll try to play with it and report back tomorrow.

I'd also post the question to wrfhelp and see if they've got some
tricks. I know there are some very sharp NCL users in MMM...

Jimmy, there's a training class in Boulder 8-11 JAN. You might try to
get into it. I'll be there seeing if I can learn another tool.

gerry

Erik Noble wrote:
> I am trying to look at 700 mb winds. Correct me if I am wrong but to do this
> brings in an extra step of interpolating to pressure level using WRF-NCL
> code.
> So first I have to interpolate the data usingthe wrf_interp-3d function and
> then use the " wrf_uvmet" function?
> -Erik
>
>
> On 12/10/07 6:33 PM, "Gerry Creager" <gerry.creager_at_tamu.edu> wrote:
>
>> At what level are you looking for U/V winds? If you're looking at the
>> surface, and using ARW, the surface U/V data are Arakawa-A grid, or,
>> destaggered.
>>
>> gerry
>>
>> jimmyc_at_iastate.edu wrote:
>>> Hi Erik-
>>> It appears you can use the functions for WRF:
>>> wrf_user_getvar to get unstaggered wind vector components
>>>
>>> But it also looks like you need to use wrf_uvmet to get those components
>>> to Earth relative coordinates.
>>>
>>> I havent tried this yet but I need to. Any advice out there?
>>> jimmyc
>>>
>>> On Mon, 10 Dec 2007, Erik Noble wrote:
>>>
>>>> Hi. I am looking at U an V variables from WRF output data. if you look
>>>> at the Lat and lon attributes of the following 2 variables, you'll
>>>> notice that they are "staggered";
>>>>
>>>> float U(Time, bottom_top, south_north, west_east_stag) ;
>>>> U:FieldType = 104 ;
>>>> U:MemoryOrder = "XYZ" ;
>>>> U:description = "x-wind component" ;
>>>> U:units = "m s-1" ;
>>>> U:stagger = "X" ;
>>>> U:coordinates = "XLONG_U XLAT_U" ;
>>>> float V(Time, bottom_top, south_north_stag, west_east) ;
>>>> V:FieldType = 104 ;
>>>> V:MemoryOrder = "XYZ" ;
>>>> V:description = "y-wind component" ;
>>>> V:units = "m s-1" ;
>>>> V:stagger = "Y" ;
>>>> V:coordinates = "XLONG_V XLAT_V" ;
>>>>
>>>> The WRF is on a Akarawa C-Grid. If I want to "unstagger" the data so
>>>> that I can compare the data to other data st regular lat and lon
>>>> ponts, does anyone have a suggestion on how to do thi in NCL?
>>>> Thank you,
>>>> Erik Noble
>>>> _______________________________________________
>>>> ncl-talk mailing list
>>>> ncl-talk_at_ucar.edu
>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>
>
>

-- 
Gerry Creager -- gerry.creager_at_tamu.edu
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