Spherical Harmonic Expansions of the Earth's Gravitational Potential to Degree 360 Using 30' Mean Anomalies
Loading...
Date
1986-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University. Division of Geodetic Science
Abstract
Two potential coefficient fields that are complete to degree and order 360 have been computed. One field (OSU86E) excludes geophysically predicted anomalies while the other (OSU86F) includes such anomalies. These fields were computed using a set of 30' mean gravity anomalies derived from satellite altimetry in the ocean areas and from land measurements in North America, Europe, Australia, Japan and a few other areas. Where no 30' data existed, 1° x 1° mean anomaly estimates were used if available. No rigorous combination of satellite and terrestrial data was carried out. Instead we took advantage of the adjusted anomalies and potential coefficients from a rigerous combination of the GEML2' potential coefficient set and 1° x 1° mean gravity anomalies. The two new fields were computed using a quadrature procedure with de-smoothing factors suggested by Colombo. The spectra of the new fields agree well with the spectra of the fields with 1° x 1° data out to degree 180. Above degree 180 the new fields have more power. The fields have been tested through comparison of Doppler station geoid undulations with undulations from various geopotential models. The agreement between the two types of undulations is approximately ±l.6 m. The use of a 360 field over a 180 field does not significantly improve the compariosn. Instead it allows the comparison to be done at some stations where high frequency effects are important. In addition maps made in areas of high frequency information (such as trench areas) clearly reveal the signal in the new fields from degree 181 to 360.
Description
Prepared for National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, Maryland: NASA Grant No. NGR 36-008-161, OSURF Project No. 783210