Extract topography or gravity data from global 1-minute grids in ASCII XYZ-format. Latitude range is +/- 80.738. Topography is V17.1 and Gravity is V23.1.

Note that odd values of topography (e.g., -2001m) are constrained by actual soundings while even values (e.g., -2000m) are predicted from gravity. Therefore one can extract the locations of the ship sounding.

359.5 360
(Any values between -360 and 360 are acceptable)

Enter data window.

west east
Topography Gravity
Note the program cannot span 0 longitude.
Also, these files can get quite large, so you may have to divide the area up into smaller chunks.

Topography Reference: Smith, W. H. F., and D. T. Sandwell, Global seafloor topography from satellite altimetry and ship depth soundings, Science, v. 277, p. 1957-1962, 26 Sept., 1997.

Gravity References: Sandwell, D. T., and W. H. F. Smith, Global marine gravity from retracked Geosat and ERS-1 altimetry: Ridge Segmentation versus spreading rate, J. Geophys. Res., 114, B01411, doi:10.1029/2008JB006008, 2009.
Sandwell, D. T., E. Garcia, K. Soofi, P. Wessel, and W. H. F. Smith, Towards 1 mGal Global Marine Gravity from CryoSat-­2, Envisat, and Jason-1, The Leading Edge, August, 2013.

Related Links

The Global Topography information page
The Marine Gravity information page
The GEODESY homepage
The IGPP homepage
The SIO homepage