LatLonGridDescriptor

A descriptor for latitude-longitude grids.

Overview

The LatLonGridDescriptor class is used to describe a regular latitude-longitude grid.

Attributes

• lat: Latitude values.

• lon: Longitude values.

Methods

• read: Reads a latitude-longitude grid from a file.

• create: Creates a latitude-longitude grid programmatically.

• to_scrip: Converts the grid to a SCRIP file.

Grid-Cell Corners

Remapping needs the corners of each grid cell, not just the cell centers. When read() is used, corners come from the CF bounds attribute of the latitude and longitude variables if it is present:

double lat(lat) ;
    lat:units = "degrees_north" ;
    lat:bounds = "lat_bnds" ;
double lat_bnds(lat, nbnd) ;

The bounds must describe contiguous cells (the upper edge of each cell is the lower edge of the next), since a 1D lat/lon grid is described by 1D arrays of corners. If the bounds attribute is missing, points to a variable that is not in the file, has the wrong shape, or describes cells with gaps or overlaps between them, corners are instead interpolated between cell centers and extrapolated at the ends of the grid, and a warning is raised in all but the first of these cases.

Example

from pyremap import LatLonGridDescriptor

descriptor = LatLonGridDescriptor.create(lat, lon)
descriptor.to_scrip("grid.scrip.nc")