Time‐variable gravity from GRACE: First results

TLDR

Eleven monthly GRACE gravity field solutions are now available for analyses. The study estimates the annually varying component of water storage in the Mississippi, Amazon, and Bay of Bengal basins to 1.0–1.5 cm accuracy. Monthly GRACE gravity fields are used to recover land and ocean water storage changes with 1.5 cm accuracy over 1000 km smoothing, and to estimate the annually varying component in major basins. The annually varying signal amplitude is determined to 1.0 cm, with 30 % improvement at 1500 km smoothing and 40 % degradation at 750 km smoothing.

Abstract

Eleven monthly GRACE gravity field solutions are now available for analyses. We show those fields can be used to recover monthly changes in water storage, both on land and in the ocean, to accuracies of 1.5 cm of water thickness when smoothed over 1000 km. The amplitude of the annually varying signal can be determined to 1.0 cm. Results are 30% better for a 1500 km smoothing radius, and 40% worse for a 750 km radius. We estimate the annually varying component of water storage for three large drainage basins (the Mississippi, the Amazon, and a region draining into the Bay of Bengal), to accuracies of 1.0–1.5 cm.