The height of the ocean surface above a datum, such as a vertical datum for sea level measurements, or a reference ellipsoid for satellite altimetric measurements.
Sea surface height is determined by the measurement of the height of the sea surface above (or below) a reference level, preferably the Earth's geoid, the actual shape of the Earth. Sea surface height variability can be used to directly infer the circulation pattern of the Earth's ocean and the strengh of ocean currents. It is also possible to use sea surface height to visualize the bathymetry of the sea floor
(due to gravity variability) and to calculate the rate of sea level rise or fall caused by climate change.
Microwave/radar (1-100 GHz)
Other sources for data