David Sandwell
June 8, 2017

The file DH.grd is the height correction in mm as described in the following publication.
A nominal effective satellite of 1000 km was used for this grid.
See Table 1 of the publication below for effective elevations of 
several altimeters.  For example CryoSat-2 has an effective altitude 
of 651 km.  To used this grid with CryoSat-2 multiply by 0.651


Sandwell, D. T., and W. H. F. Smith, Slope Correction for Ocean Radar Altimetry, 
Journal of Geodesy, DOI 10.1007/s00190-014-0720-1, 2013.
http://topex.ucsd.edu/sandwell/publications/149.pdf