The -new_grid_winds option selects the wind rotation/orientation
for the -new_grid option. Most users will want the winds
to be oriented to the earth's north and south directions. This is done by using the
-new_grid_winds earth option. Many of NCEP grids have the
winds being rotated so that north direction is relative to the grid; i.e.,
grid point (i,j) to (i,j+1). For lat-lon, Mercator and Gaussian grids, the grid
and earth relative directions are the same. For the Lambert conformal, polar
stereographic and various rotated grids, the directions are different.
To make the interpolated wind fields have a earth (grid) orientation, you have
to use the -new_grid_winds earth or to use the
-new_grid_winds grid option before doing the interpolation.
The exception is the "-new_grid grib". In this case, the grid definition and default
wind rotation is read from a grib file. In this case, a -new_grid_winds option
will override the wind rotation read from the file.
The wind orientation applies to all the identified vector fields:
"UGRD", "VGRD", "VUCSH", "VVCSH","UFLX", "VFLX", "UGUST","VGUST","USTM","VSTM","VDFUA", "VDFVA",
In the future, the wind orientation will be a part of the -new_grid option.
However, the current systax will still work.
X = earth, grid
See also: -new_grid,