Satellite Measurements of Sea Level Change: Past, Present, and Future

Measurements from TOPEX/Poseidon, Jason-1, Jason-2, Jason-3, and Sentinel-6 Michael Freilich have provided an uninterrupted 31-year time series of sea surface height measurements. With these measurements, changes in sea level can be precisely measured. This talk will review what we have learned from this invaluable climate data record. Global average sea level change is one variable that show us how the oceans and ice sheets are responding to climate change, but geographic variations in sea level rise have also revealed new information on ocean physics and where sea level rise might be greater than the global average. The spatial and temporal resolution of this climate data record provide much more insight than could be obtained from conventional land-based tide gauge measurements alone. Global mean sea level change is an excellent barometer of how much heat is being absorbed by the oceans and how much water is being added to the oceans from melting ice. Together with satellite gravity measurements (GRACE and GRACE-FO) of ice mass change over the last 21 years, the causes of sea level change are very well understood from satellite observations. The insight provided by the satellite observations provide pathways to the successful prediction of future regional sea level patterns independent of climate model projections. Additional satellite missions planned after Sentinel-6 MF promise to lengthen the altimeter time series, and additional satellite gravity missions are also in the planning stages. Finally, the SWOT (Surface Water Ocean Topography) Mission, launched in December 2022, is defining a new paradigm for future measurements of sea surface height.