This is the DTU21 Mean Sea surface (MSS) from DTU. The 1-minute high resolution Mean Sea Surface is computed over the 1993-2012 period from multiple satellites.
The MSS is available online in two file formats and in two reference systems.
Reference system:
TOPEX ellipsoid:
WGS84 ellipsoid (WGS84)
Fileformat:
XYZ (ASCII format. Grid is written out as point locations).
Gravsoft: DTU Space ASCII file format .
Grid contains: 10800 cells (latitude) x 21602 cells in longitude.