Re: How to call wind direction variables in NCL from U and V wind vectors

rad = 4.*atan(1.0)/180.
wDir = atan2(ue,v)/rad +180.

Pick a color table

   res@gsnSpreadColors = True ; use full range of color map

   res@cnLevelSelectionMode = "ManualLevels" ; set contour levels
   res@cnMinLevelValF = 10. ; set min contour level
   res@cnMaxLevelValF = 350. ; set max contour level
   res@cnLevelSpacingF = 10. ; set contour spacing

On 6/8/10 5:27 PM, David Brown wrote:
> Use atan2 (http://www.ncl.ucar.edu/Document/Functions/Built-in/atan2.shtml
> )
> -dave
>
> On Jun 8, 2010, at 5:24 PM, Jinwoong Yoo wrote:
>
>> Hi.
>>
>> I'd like to plot wind directions colored by azimuth angle for a
>> visual effect.
>> I'm using NCEP/NCAR Reanalysis data so wind vector comes from u and v.
>>
>> Since wind direction can be plotted with such as arrows or wind barbs,
>> I assume that there should be a way to call the wind direction.
>>
>> If the wind direction (like from 0 to 360 degree to the north)can be
>> called,
>> I think wind directions can be plotted with color as a scalar using
>> plot
>> function such as gsn_csm_vector_scalar_map_ce.
>>
>> Does anybody know how to call the wind direction?
>>
>> Thank you.
>>
>>
>> Jinwoong Yoo
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Received on Tue Jun 8 17:51:23 2010