Introduction

The -wind_uv option takes the wind speed and wind direction and computes the zonal (UGRD) and meridional (VGRD) wind components. The wind components are then written out in grib format. For this option to work, the corresponding wind direction and speed must not be separated by a non-corresponding wind speed or direction. If the speed and direction do no have this order, the file must be sorted.

If the wind direction is earth (grid) relative, the UGRD and VGRD winds are earth (grid) relative.

You can save computer time by using the -match option to restricting the decoding of records to wind speed (WIND) and wind direction (WDIR).

Usage

-wind_uv output_grib_file

Example

$ wgrib2 gep19.t00z.pgrb2af180 -wind_dir wind.grb -wind_speed wind.grb -match "(UGRD|VGRD)"
4.1:86046:d=2009060500:UGRD:200 mb:180 hour fcst:ENS=+19
4.2:86046:d=2009060500:VGRD:200 mb:180 hour fcst:ENS=+19
8.1:226831:d=2009060500:UGRD:250 mb:180 hour fcst:ENS=+19
8.2:226831:d=2009060500:VGRD:250 mb:180 hour fcst:ENS=+19

$ wgrib2 wind.grb -wind_uv uv.grb
1:0:d=2009060500:WDIR:200 mb:180 hour fcst:ENS=+19
2:97922:d=2009060500:WIND:200 mb:180 hour fcst:ENS=+19
3:179554:d=2009060500:WDIR:250 mb:180 hour fcst:ENS=+19
4:277476:d=2009060500:WIND:250 mb:180 hour fcst:ENS=+19

$ wgrib2 uv.grb
1:0:d=2009060500:UGRD:200 mb:180 hour fcst:ENS=+19
2:89777:d=2009060500:UGRD:200 mb:180 hour fcst:ENS=+19
3:179554:d=2009060500:UGRD:250 mb:180 hour fcst:ENS=+19
4:269331:d=2009060500:UGRD:250 mb:180 hour fcst:ENS=+19

See also: -match, -wind_speed -wind_dir