Fwd: Re: Calculate wind speed and bearing from WRF U and V components

wrfhelp sent the following to me ...

-------- Original Message --------
Subject: Re: [ncl-talk] Calculate wind speed and bearing from WRF U and
V components
Date: Tue, 14 Jun 2011 08:00:21 -0600
From: wrfhelp <wrfhelp@ucar.edu>

Wind speed is just the following
spd = (u_plane*u_plane + v_plane*v_plane)^(0.5) ; m/sec

To plot wind vectors you can do this with "wrf_vector"
Se this example
http://www.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/Examples/LEVELS_INTERP/wrf_PressureLevel1.ncl
Note that in this example we also convert to pressure level, which you
do not have to do if you do not want to.

Also - if you plan on plotting the data on a map, then you do not have
to use uvmet, you can just use ua and va.

Hope this helped
wrfhelp
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On Jun 5, 2011, at 9:18 PM, Dennis Shea wrote:

> This has been forwarded to wrfhelp@ucar.edu <mailto:wrfhelp@ucar.edu>
>
> On 6/5/11 6:12 PM, Phil Howarth wrote:
>> Gday all,
>>
>> What is the "NCL way" to compute the wind speed and bearing angle from U
>> an V components output from WRF.
>>
>> UV = wrf_user_getvar(a,"uvmet",it)
>>
>> U_profile = UV(0,:,index_min(0,0),index_min(0,1))
>> V_profile = UV(1,:,index_min(0,0),index_min(0,1))
>>
>>
>> Regards
>>
>> PHil Howarth
>>
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>>
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>>
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Received on Tue Jun 14 08:24:07 2011