The EGM96 combination solution to 70x70 included an adjustment for the static geopotential, tidal harmonic constituents, Earth orientation parameters, station coordinates and coefficients representing the dynamic ocean topography for GEOSAT and TOPEX/ERS-1.

The tidal adjustment included 56 harmonic constituents representing 12 major tide lines. The selection of these tidal coefficients was based on their effect on the T/P orbit. The ocean tidal modeling and parameter recovery is made in the presence of a frequency dependent model of the solid Earth tides.

Tidal Constituents Adjusted in EGM96

Main Line Constituent Degree, Order of
Adjusted Terms
Number of Adjusted
Sa (2,0) to (3,0) 2
Ssa (2,0) to (3,0) 4
Mf (2,0) to (5,0) 4
Mm (2,0) to (3,0) 2
K1 (2,1) to (6,1) 5
O1 (2,1) to (6,1) 5
P1 (2,1) to (5,1) 4
Q1 (2,1) to (5,1) 4
K2 (2,2) to (6,2) 5
M2 (2,2) to (8,2) 7
S2 (2,2) to (7,2) 6
N2 (2,2) to (6,2) 5
T2 (2,2) to (6,2) 5

The following files are available that describe the EGM96 tide model:

A short summary (postscript file) of the tides in the EGM96 solution, extracted from the EGM96 technical report, which is currently undergoing final editting. The summary includes (1) a comparison of the GEM-T3 derived and the EGM96 tidal solutions. (2) A comparison of the ocean tidal resonant terms from the EGM96 solution, with those computed from altimeter data.


EGM96 tides in GEODYN format for GEODYN users only. Includes background Earth and ocean and tide terms that were not adjusted. Note this file is intended only for those interested in using the EGM96 tides in their orbit determination software. The formulation is compatible only for users of GEODYN or VAN MARTIN SYSTEMS Microcosm.

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Last revised January 18, 2006 17:25 UTC