Table 1. Statistics of global 30' mean free-air anomaly merged file.
DMA
DMA
OSU
OSU
Topo/lso
Type
Terr. 30'
Altim.30'
Terr. 30'
Terr. 60'
Fill-in 30'
Number
72776
140701
4514
15291
25918
% of Area
29.7
65.1
0.5
1.4
3.3
RMS ~g (mgal)
34.3
25.5
36.6
31.9
28.1
RMS cr (mgal)
5.6
1.7
17.4
38.5
36.0
SUMMARY
The development of the final global surface gravity database shown in Fig. 1, has
paralleled the computation of the ocean wide altimetry-derived anomaly file used in this
project. The formation of these databases represent the largest geodetic computer project
ever attempted at DMA. Preliminary models which employed these data (Nerem et al.,
this issue) have demonstrated significant improvements over pre-existing models in areas
such as the former USSR, Greenland, Canada, Scandinavia, Africa, China, S. America,
and the Middle East. The final shipment of the global surface gravity database was
delivered to GSFC on October 26, 1995.
REFERENCES
Forsberg, R., A New Covariance Model for Inertia, Gravimetry and Gradiometry, J.
Geophys. Res., 92, B2, 1305-1310, 1987.
Forsberg, R., A Study of Terrain Reductions, Density Anomalies and Geophysical
Inversion Methods in Gravity Field Modeling, Dept. of Geod. Sci. and Surv. Rep.
355, Ohio State Univ., Columbus, 1984.
Heck, B., An evaluation of some systematic error sources affecting terrestrial gravity
anomalies, Bull. Geod., 64, 88-108, 1990.
Heiskanen, W.A. and H. Moritz, Physical Geodesy, W.H. Freeman, San Francisco, 1967.
Moritz, H., Advanced Physical Geodesy, Herbert Wichmann Verlag, Karlsruhe, 1980.
Nerem, R.S., et al., Gravity model development for TOPEX/POSEIDON: Joint Gravity
Models 1 and 2, J. Geophys. Res., 99, 24421-24447, 1994.
Pavlis, N.K. and R.H. Rapp, The development of an isostatic gravitational model to
degree 360 and its use in global gravity modeling, Geophys. J. Int., 100, 369-378,
1990.
Rapp, R.H. and N.K. Pavlis, The development and analysis of geopotential coefficient
models to spherical harmonic degree 360, J. Geophys. Res., 95, 21885- 21911, 1990.
Rapp, R.H., Y.M. Wang and N.K. Pavlis, The Ohio State 1991 geopotential and sea
surface topography harmonic coefficient models, Dept. ofGeod. Sci. and Surv. Rep.
410, Ohio State Univ., Columbus, 1991.
Row, L.W., D.A. Hastings and P.K. Dunbar, TerrainBase Worldwide Digital Terrain
Data, National Geophysical Data Center, Boulder, Colorado, April 1995.
Tscheming, C.c. and R.H. Rapp, Closed covariance expressions for gravity anomalies,
geoid undulations, and deflections of the vertical implied by degree-variance models,
Dept. ofGeod. Sci. Rep. 208, Ohio State Univ., Columbus, 1974.
Votila, V.A., Computation of Mean Anomalies of lOx 1 0 Blocks, Dept. of Geod. Sci.
Rep. 95, Ohio State Vniv., Columbus, 1967.
91
DMA
DMA
OSU
OSU
Topo/lso
Type
Terr. 30'
Altim.30'
Terr. 30'
Terr. 60'
Fill-in 30'
Number
72776
140701
4514
15291
25918
% of Area
29.7
65.1
0.5
1.4
3.3
RMS ~g (mgal)
34.3
25.5
36.6
31.9
28.1
RMS cr (mgal)
5.6
1.7
17.4
38.5
36.0
SUMMARY
The development of the final global surface gravity database shown in Fig. 1, has
paralleled the computation of the ocean wide altimetry-derived anomaly file used in this
project. The formation of these databases represent the largest geodetic computer project
ever attempted at DMA. Preliminary models which employed these data (Nerem et al.,
this issue) have demonstrated significant improvements over pre-existing models in areas
such as the former USSR, Greenland, Canada, Scandinavia, Africa, China, S. America,
and the Middle East. The final shipment of the global surface gravity database was
delivered to GSFC on October 26, 1995.
REFERENCES
Forsberg, R., A New Covariance Model for Inertia, Gravimetry and Gradiometry, J.
Geophys. Res., 92, B2, 1305-1310, 1987.
Forsberg, R., A Study of Terrain Reductions, Density Anomalies and Geophysical
Inversion Methods in Gravity Field Modeling, Dept. of Geod. Sci. and Surv. Rep.
355, Ohio State Univ., Columbus, 1984.
Heck, B., An evaluation of some systematic error sources affecting terrestrial gravity
anomalies, Bull. Geod., 64, 88-108, 1990.
Heiskanen, W.A. and H. Moritz, Physical Geodesy, W.H. Freeman, San Francisco, 1967.
Moritz, H., Advanced Physical Geodesy, Herbert Wichmann Verlag, Karlsruhe, 1980.
Nerem, R.S., et al., Gravity model development for TOPEX/POSEIDON: Joint Gravity
Models 1 and 2, J. Geophys. Res., 99, 24421-24447, 1994.
Pavlis, N.K. and R.H. Rapp, The development of an isostatic gravitational model to
degree 360 and its use in global gravity modeling, Geophys. J. Int., 100, 369-378,
1990.
Rapp, R.H. and N.K. Pavlis, The development and analysis of geopotential coefficient
models to spherical harmonic degree 360, J. Geophys. Res., 95, 21885- 21911, 1990.
Rapp, R.H., Y.M. Wang and N.K. Pavlis, The Ohio State 1991 geopotential and sea
surface topography harmonic coefficient models, Dept. ofGeod. Sci. and Surv. Rep.
410, Ohio State Univ., Columbus, 1991.
Row, L.W., D.A. Hastings and P.K. Dunbar, TerrainBase Worldwide Digital Terrain
Data, National Geophysical Data Center, Boulder, Colorado, April 1995.
Tscheming, C.c. and R.H. Rapp, Closed covariance expressions for gravity anomalies,
geoid undulations, and deflections of the vertical implied by degree-variance models,
Dept. ofGeod. Sci. Rep. 208, Ohio State Univ., Columbus, 1974.
Votila, V.A., Computation of Mean Anomalies of lOx 1 0 Blocks, Dept. of Geod. Sci.
Rep. 95, Ohio State Vniv., Columbus, 1967.
91