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-lola

Introduction

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.

Interpolation scheme

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.

Usage

-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).

Comments

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 lat-lon grids.

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

Description: out X..Z,A lon-lat grid values X=lon0:nlon:dlon Y=lat0:nlat:dlat Z=file A=[bin|text|spread|grib]

Docs derived from https://www.cpc.ncep.noaa.gov/products/wesley/wgrib2/lola.html