[gradsusr] gr2stn and wind direction from ugrd and vgrd

[Jonas Kaufmann]

Hello,

I am using GFS model to generate wind forecasts for different locations. To
do an interpolation on a station level, I am using the gr2stn function.
However I came across a problem with wind direction there.

With winds turning around northerly directions, the computed wind direction
sometimes displays completely irregular values, for example switching to
southeasterly winds in one forecast horizon and then getting back to north.
I think there might be an error in handling of ugrd/vgrd data in gr2stn()
or I am doing something wrong.

Here is the way I extract wind direction:
'd gr2stn(atan2(ugrd10m,vgrd10m),<lon>,<lat>)*57.2957795+180.0)'


Can you give me a hint what I am doing wrong? Is there another way to
interpolate wind direction to stations? Thank you for your help!


Best regards,

Jonas
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