Temporal Variability of Earth’s Gravitational Field from Satellite Laser Ranging

Satellite laser ranging (SLR) observations of geodetic satellites (Degnan, 1993) have long been used to study the temporal variations of the Earth’s external potential through the long-period orbital perturbations they produce (Yoder et al., 1983; Rubincam, 1984; Cheng et al., 1989; Tapley et al., 1993; Gegout and Cazenave, 1993; Nerem et al., 1993; Chao and Eanes, 1995; Nerem and Klosko, 1995.) Secular and long period variations in the zonal Stokes coefficients and nearly diurnal and semidiurnal tidal variations in the order 1 and 2 coefficients can be monitored with this approach. In this paper we analyze SLR observations of Lageos-1 and Starlette and present new results for constraints on the secular and 18.6-year variations in the zonal harmonics. These results provide important information for improving geophysical models of glacial rebound, ice-sheet changes, and mantle anelasticity.