Gravity model determination from the GRACE mission

Abstract

The Gravity Recovery and Climate Experiment (GRACE) is a collaborative NASA and DLR mission whose satellites were launched on March 17, 2002 as the first of the Earth System Science Pathfinder (ESSP) Missions. The purpose of the GRACE mission is to characterize the spatial and temporal variations in the Earth’s mass, through precise measurements of its gravity field. This is accomplished by using micron level inter-satellite range measurements to determine monthly solutions for the Earth’s global gravity field. The GRACE mission has provided 82 monthly solutions that have led to unprecedented improvements in the mean gravity field accuracy and a seven-year record of monthly gravity signals associated with the global mass flux. This continuous, multi-year record of monthly measurements supports investigations that characterize the seasonal cycle of mass transport between the oceans, land, and atmosphere; observes its inter-annual variability; and monitors the secular trends in mass transport. In the following discussion, the overall mission concept is described, the approach to the gravity model determination is discussed, and the mission progress is partially summarized.