GEBCO General Bathymetric Chart of the Oceans

In the September 2010 issue of Oceanography magazine, Paul Wessel describes his computation of "distance to coastline" based on the GSHHS shoreline database.

I have performed some similar calculations based on the GEBCO database:

Maps of distance to shoreline are used when processing satellite altimeter data, for example, where it may be necessary to exclude data close to land.

Distances between points are computed using the Bowring formula for an ellipsoidal earth. Depth iso-levels are defined as the GEBCO grid cell edges which fall between cell-centers above and below the given iso-level. Computations are performed in Matlab using a home-spun parallelization toolbox written in Tcl. The Matlab code has been hand-tuned to compute efficiently, but the computations still take a few days to complete.

Files for download: