## Wind direction?

### Wind direction?

Dear All,

How to get the wind direction from WRF?

Please let me know how to calculate the wind direction or get it.

Best Regards
JY
colopolo70

Posts: 47
Joined: Thu Jan 15, 2009 10:38 am

### Re: Wind direction?

You can calculate wind direction from the component vectors U (x direction) and V (y direction).

Be aware though, U and V are relative to the WRF model grid, so they may need to be rotated to be relative to the earth. This can be achieved by

Uearth = U*cosalpha + V*sinalpha, and
Vearth = V*cosalpha - U*sinalpha.

Also, be aware that if you want to compare this to observations, these typically record the direction the wind is blowing from, in degrees from North, so you need to make sure you compute this from the component vectors.
samhawkins

Posts: 4
Joined: Wed Jan 14, 2009 11:12 am

### Re: Wind direction?

****** ATTENTION ALL WRF USERS USING THIS FORMULA!!!!!!! **********

The above formula is incorrect. The real formula can be found on the WRF users page:
http://www2.mmm.ucar.edu/wrf/users/FAQ_ ... neous.html

u-earth = u-model*cosalpha - v-model*sinalpha
v-earth = v-model*cosalpha + u-model*sinalpha
gmantegna

Posts: 1
Joined: Mon Aug 15, 2016 10:08 am