Altimetry
D5. Coastal processes, sea-level, cryosphere and ocean observation scienceDefinition
Measurement of sea surface height using radar from satellites.
Satellite altimetry measures sea surface height by timing a radar pulse to the surface and back, corrected for orbit, tides, and atmospheric delay. The continuous record from TOPEX/Poseidon (1992) through the Jason series to Sentinel-6 underpins the global mean sea level trend of about 3.3 to 3.4 mm per year. SWOT extended the technique to two-dimensional swaths in 2023, resolving mesoscale eddies and coastal sea level that nadir altimeters miss.