気圧荷重による重力変化を用いた荷重Green関数の推定 Estimation of a Load Green's Function Employing Gravity Changes Induced by Atmospheric Pressure Loadings
A load Green's function for gravity is estimated by an inversion method employing gravity changes induced by atmospheric pressure loadings. The gravity data were derived from a superconducting gravimeter at Kyoto University . We introduce a theoretically estimated load Green's function as a priori data for calculating a minimum variance solution. A region from the observation point to 4° in angular distance is divided into four sub-regions, width of which is 1°. Parameters to be solved are average values of the unknown load Green's function of the four sub-regions . The parameters are estimated for two periods from December 1989 to February 1990 and from May 1990 to January 1991. The results for the two periods indicate good agreement with each other. In comparison with theoretical values, the results for the nearest region are consistent with the theoretically expected value and those for other regions have smaller absoulte values. Especially, the values for the farthest region are about 60% of the theoretically expected one. We did not take into account any assumption about the ocean response to atmospheric pressure changes in this estimation . Since most part of the farthest region is occupied by the ocean, the results will reflect small response of the ocean to atmospheric pressure changes. Residuals after removal of loading effects from input data decreased by using the observationally estimated results instead of the theoretical values. This means that the results provide a suitable load Green's function at the observation point .
測地学会誌 43(1), 13-21, 1997-03-25
The Geodetic Society of Japan