Using Envisat radar altimeter data, scientists from the Centre for Polar Observation and Modelling at University College London (UCL) measured sea ice thickness over the Arctic from 2002 to 2008 and found that it had been fairly constant until the record loss of ice in the summer of 2007. (sciencecodex.com)
In particular, we aim for a detection of MYI floes in a area composed mostly first - year ice from synthetic aperture radar (SAR), heavily ridged ice regions from SAR, the thickest ice from radar altimeter (RA) thickness profiles, regional anomalies of thick or thin ice via passive microwave (PMW) data, sea ice areas vulnerable for the wave action, detection of early / late melting season and improving capabilities to forecast seasonal sea ice extremes. (nersc.no)
In the early 1990s the TOPEX (Topography Experiment for Ocean Circulation) / Poseidon satellite, a joint American - French mission, shot into orbit armed with radar altimeters to measure the height of the sea surface. (discovermagazine.com)