For visualisation, you could plot both grids on top of each other with grdcontour (see the doc).
For a number approach, depends on what you want to look at, but grdmath has a decent set of operators that would fit the job.
For visualisation, you could plot both grids on top of each other with grdcontour (see the doc).
For a number approach, depends on what you want to look at, but grdmath has a decent set of operators that would fit the job.