Satellite gravity field observations

The Gravity Recovery and Climate Experiment (GRACE) and the Gravity field and steady-state Ocean Circulation Explorer (GOCE) missions map Earth's gravitational field. Variations in Earth’s gravitational field arise from: changes due to surface and deep currents in the ocean; runoff and ground water storage on land masses; exchanges between ice sheets or glaciers and the oceans; and variations of mass within the Earth. Argo estimates of ocean thermal expansion in combination with altimeter data, will provide an independent estimate of ocean freshwater input to cross-validate with GRACE and GOCE. Argo observations of changes in sub-surface temperature and salinity will also combine with gravity field observations to aid our understanding of changes in ocean circulation, using geostrophy.