Rio Mean Dynamic Topography

The Rio mean dynamic topography is the CNES-CLS mean dynamic topography (MDT) product, the time-mean height of the sea surface above the geoid that serves as the reference surface for satellite altimetry. Named for lead author Marie-Helene Rio, the successive releases (CNES-CLS09, 13, 18, 22) merge altimeter sea-surface-height data, the GRACE and GOCE gravity-field geoid, and in situ drifter velocities and hydrographic profiles. Adding the altimeter sea-level anomaly to the MDT gives absolute dynamic topography, whose surface gradients yield the surface geostrophic current under the geostrophic balance. It is the standard MDT behind operational altimetric current products.