Geoid Map

Image Name : ww15mgh

Boundaries : Lat -90N to 90N ;

Lon 0E to 360E

Color Scale, Upper (Red) : 85.4 meters and higher

Color Scale, Lower (Magenta) :-107.0 meters and lower

Data Max value : 85.4 meters

Data Min value :-107.0 meters

Illuminated from the : East

This is an image generated from 15'x15' geoid undulations covering the planet Earth. These undulations represent the NIMA/GSFC WGS-84 EGM96 15' Geoid Height File. This file is a global grid of undulations generated from: (a) the EGM96 spherical harmonic coefficients and (b) correction terms that convert pseudo-height anomalies on the ellipsoid to geoid undulations.

This file may be found at: http://164.214.2.59/geospatial/products/GandG/wgs-84/geos.html

The undulations in this file refer to the WGS-84(G873) reference ellipsoid.

We are deeply indebted to the NIMA/GSFC EGM96 team for their work on EGM96 and this grid of associated geoid undulations.

Some interesting features to note about this image are: Even at 15' resolution, some beautiful features of the global geoid are obvious.

• The major trench systems have obvious impacts on the geoid, as well as the topography/ocean boundaries (whose geoid signals closely coincide with the shoreline).
• The Hawaiian Island chain may be followed up through its transition into the Emperor Seamounts and toward the western end of the Aleutian Islands.
• The structure of seamounts with the Marshall Islands, east of the Mariana Trench, can be seen in the geoid signal in that area.
• Finally, the well-known geoid low near the tip of India, and the geoid high over New Guinea stand out, with a great deal of finely detailed structures mixed in with these broad features.

Map and description from the National Geodetic Survey.