Excitation of Non-atmospheric Polar Motion by the Migration of the Pacific Warm Pool
【摘要】：正Changes in the annual variation of the Earth's polar motion are found to be largely caused by the variation of the atmospheric angular momentum (AAM). Recent simulation results of oceanic general circulation models further suggested global oceanic effects on the annual polar morion other than the atmosphere. In comparison with previous model studies of global oceanic effects, this research particularly singles out a large-scale ocean anomaly and investigates its effect on the annual polar motion, determined from satellite observations of the movement of the Western Pacific Warm Pool (WPWP). Although the scale of the warm pool is much smaller than that of the solid Earth, analysis of the non-atmospheric polar motion excitation has shown that the WPWP contributes nonnegligibly to the annual polar motion. The analysis consists of over thirty years of the WPWP data (1970 ～2000) and shows values of the polar motion excitation for the x-component of (2.5mas, -79°) and (0.6mas, 173°) for the y-component. Comparing this result with the total geodetic nonatmospheric polar motion excitation of (10.3mas, 59°) for the x-component and (10.6mas, 62°) for the y-component, shows the significance of the WPWP. Changes in the Earth's polar motion have attracted significant attention, not only because it is an important geodetic issue, but also because it has significant value as a global measure of variations within the hydrosphere, atmosphere, cryosphere, and solid Earth, and hence global changes.