Regridding to and/or from a very large grid (in terms of number of grid points) can fail due to running out of memory.

This occurs during the call to esmpy.Regrid which we use to calculate the regridding weights (https://github.com/NCAS-CMS/cf-python/blob/v3.18.0/cf/regrid/regrid.py#L2434). The problem isn't (so much) the size of the final weights matrix (although that can be quite large), more that esmpy.Regrid uses up a lot of memory for temporary arrays.

A real use case using 'linear' regridding has destination grid size 181440000, resulting in a sparse matrix representation of the weights taking up