The Development of a Global Surface Gravity Data Base to be Used in the
loint DMA/GSFC Geopotential Model
S. C. Kenyon
Defense Mapping Agency, Geodesy and Geophysics Dept.
3200 South Second Street, St. Louis, MO 63118
e-mail: kenyonS@dma.gov
N. K. Pavlis
Hughes STX Corp., 7701 Greenbelt Rd., Greenbelt, MD 20770
e-mail: zmnkp@gibbs.gsfc.nasa.gov
ABSTRACT
The Defense Mapping Agency (DMA) and NASNGoddard Space Flight Center (GSFC)
are currently involved in the development of a global gravity model complete to degree
and order 360. This effort requires the compilation of a worldwide set of 30'x30' surface
mean free-air gravity anomalies. The extensive data archive at DMA is the main source
of gravity information from which the 30' mean values are estimated. New sources of
terrestrial gravity data used in the model will include the former Soviet Union,
Greenland, South America, Africa, Southeast Asia, Antarctica, and the Arctic.
Improvements to current terrestrial sources have been made in North America, Europe,
and Australia. However, several areas have been identified which are still lacking detailed
and accurate gravity information and emphasize the need to intensify data collection
efforts. Substantial effort is made to ensure accurate and consistent processing of the
point gravity anomaly data used in the estimation of the 30' mean values. This effort is
aimed at producing a global set of mean values with significantly reduced long
wavelength systematic errors. The mean values and their accuracies are estimated using
least-squares collocation and remove-restore techniques implemented at DMA. For the
reduction process, consistent l' and 5' elevation databases were compiled by DMA and
GSFC using the best worldwide elevation sources currently available. This paper
describes the data being used in the project and the computational procedures being
implemented.
INTRODUCTION
The Defense Mapping Agency, NASA/GSFC, and The Ohio State University are
cooperating in a joint effort to significantly improve the current spherical harmonic
models of the Earth's gravitational potential to degree and order 360 (Rapp and Pavlis,
1990). This new model will incorporate improved global surface gravity data, new and
existing satellite data, and satellite altimeter anomalies from the GEOSA T Geodetic
Mission and ERS-l. The new spherical harmonic model will be used to determine a geoid
undulation model accurate to ±1.0 meter and realize WGS-84 as a true 3-dimensional
reference system. Additional benefits of the new model will be improved sea surface
topography models, satellite orbit determinations and other gravimetric applications.
82
loint DMA/GSFC Geopotential Model
S. C. Kenyon
Defense Mapping Agency, Geodesy and Geophysics Dept.
3200 South Second Street, St. Louis, MO 63118
e-mail: kenyonS@dma.gov
N. K. Pavlis
Hughes STX Corp., 7701 Greenbelt Rd., Greenbelt, MD 20770
e-mail: zmnkp@gibbs.gsfc.nasa.gov
ABSTRACT
The Defense Mapping Agency (DMA) and NASNGoddard Space Flight Center (GSFC)
are currently involved in the development of a global gravity model complete to degree
and order 360. This effort requires the compilation of a worldwide set of 30'x30' surface
mean free-air gravity anomalies. The extensive data archive at DMA is the main source
of gravity information from which the 30' mean values are estimated. New sources of
terrestrial gravity data used in the model will include the former Soviet Union,
Greenland, South America, Africa, Southeast Asia, Antarctica, and the Arctic.
Improvements to current terrestrial sources have been made in North America, Europe,
and Australia. However, several areas have been identified which are still lacking detailed
and accurate gravity information and emphasize the need to intensify data collection
efforts. Substantial effort is made to ensure accurate and consistent processing of the
point gravity anomaly data used in the estimation of the 30' mean values. This effort is
aimed at producing a global set of mean values with significantly reduced long
wavelength systematic errors. The mean values and their accuracies are estimated using
least-squares collocation and remove-restore techniques implemented at DMA. For the
reduction process, consistent l' and 5' elevation databases were compiled by DMA and
GSFC using the best worldwide elevation sources currently available. This paper
describes the data being used in the project and the computational procedures being
implemented.
INTRODUCTION
The Defense Mapping Agency, NASA/GSFC, and The Ohio State University are
cooperating in a joint effort to significantly improve the current spherical harmonic
models of the Earth's gravitational potential to degree and order 360 (Rapp and Pavlis,
1990). This new model will incorporate improved global surface gravity data, new and
existing satellite data, and satellite altimeter anomalies from the GEOSA T Geodetic
Mission and ERS-l. The new spherical harmonic model will be used to determine a geoid
undulation model accurate to ±1.0 meter and realize WGS-84 as a true 3-dimensional
reference system. Additional benefits of the new model will be improved sea surface
topography models, satellite orbit determinations and other gravimetric applications.
82