Altimetry: Past, Present and Future

This visualization shows the progression of improved data resolution from satellite altimeters in the past, present, and future, beginning with 1.5-degree resolution data in 1978 from Seasat and ending with 0.05-degree resolution data from NASA's Surface Water and Ocean Topography (SWOT) mission, planned to launch in 2021.

Launched in 1978, Seasat was the first NASA Earth-orbiting satellite mission designed to observe the world's ocean. Seasat carried five major instruments, including a radar altimeter that measured the distance between the satellite and sea surface, indicating global sea surface height and the topography of the ocean surface. A single satellite (Geosat) provided 0.5-degree resolution data from 1986 to 1990, while numerous international satellite missions (ERS-1, TOPEX/Poseidon, ERS-2, Jason-1, Envisat, and Jason-2) have provided 0.25-degree resolution data from 1992 until now.

SWOT (with 0.05-degree-resolution) will offer an unprecedented combination of spatial and temporal resolution while continuing and extending the ocean altimeter data record for years to come.