I have a gridded global bathymetric database with X, Y, and E. X is longitude, Y is latitude, and E is the elevation. E can be positive numbers (elevation of land, mountains, etc.), or negative numbers (depth of the ocean). They all share the same size of 8640 x 4320.
How do I use this database to create a land/sea mask, i.e., a value of 1 (land) or 0 (sea) for each point on a global grid like the below:
[X, Y] = ndgrid([-180:0.125:180], [-90:0.125:90]);
Any ideas would be greatly appreciated!