The -lola option was not named after a girl but for extracting data
on a LOngitude-LAtitude grid. You need to specify the lower
left corner of the grid, the number of points in the zonal and meridional directions
and the latitude/longitude increments. Finally you need to specify the output file
and the format. WARNING: winds and other vector fields will not be
rotated. If the vector fields use a grid relative orientation,
then your interpolated winds will be using the original grid.
The interpolation to the lola grid is by nearest neighbor. Sure there are more
accurate schemes and people are welcome to do better. Warning: the interpolation
scheme simply picks up the value of the nearest neighbor. This can be very
inaccurate for winds and other vectors near the pole.
-lola LonSW:#lon:dlon LatSW:#lat:dlat file format
LonSW Longitude of the South-West point, values from 0 .. 360
#lon number of longitude points
dlon spacing of the points in the zonal direction in degrees
LatSW Latitude of the South-West point, values from -90 .. 90
#lat number of latitude points
dlat spacing of the points in the meridional direction in degrees
file name of the output file
format format of the output file: bin, text, spread
bin = binary
text = simple "text" format, one value per line
spread = spread-sheet format, latitude, longitude and value of each grid point
grib = grib2
The order of the data points is WE:SN (wgrib2 standard).
I dislike this routine. It is slow, uses a simplistic interpolation
scheme and doesn't handle rotated winds in a useful manner.
The grib file support allows you to make lat-lon templates which is used by
g2grb.gs. As much as I dislike this routine, I keep using it for interpolations.
Keep wanting to modify it to do bilinear interpolations for interpolating from
5/2010: interpolation from regular lat-lon grids is now handled as special case.
This speeds up the interpolation and paves the way for a bilinear interpolation
for the special cases.
See alse: -lon