This learning activity uses data acquired by the TOPEX/Poseidon altimeter, a joint project of NASA and the French Space Agency, to investigate the relationship between the topography of a sea-floor feature and the topography of the overlying sea surface.

For over 20 years, satellite instruments have measured the sea surface height of our ever-changing oceans.  This video of images shows the complicated patterns of rising and falling ocean levels across the globe from 1993 to 2015.