CoAuthors

Fanny Piras (CLS, France); Maël Smessaert (CLS, France); Pierre Thibaut (CLS, France); Amandine Guillot (CNES, France); François Boy (CNES, France); Nicolas Picot (CNES, France); Jérôme Bouffard (ESA, Italy); Pierre Féménias (ESA, Italy)

For many years, radar altimeter measurements have been exploited in sea ice regions to retrieve the freeboard height from which the sea ice thickness is derived. Sea Ice regions are very complex for radar altimeters because different surface types (water, sea ice, etc ..) are mixed in the altimeter footprint. Each altimetry mission has its own instrumental characteristics (different radar techniques, different radar frequencies, etc…) and specific processing algorithms have been developed to extract and monitor sea ice extent, freeboard height and sea level of the ice-covered ocean.

When using empirical retracking approaches (which is the technique mostly employed up to now), sea ice processing must be adapted to each mission, which makes the combination of two or more satellites very complex and uncertain. In the frame of different CNES (PEACHI, AltiGlacio) and ESA projects (Sea Level CCI, CryoSeaNIce, CS+ Antarctica), CLS has developed and validated new sea ice lead identification methods and new retracking algorithms based on a physical modelling of the signal whatever the altimeter mode (LRM / SAR) and frequency (Ku/Ka). Thanks to these innovative algorithms, we are now able to derive improved multi-mission sea ice extent, concentration, freeboard, lead concentration and sea level anomaly maps of better quality. In this talk, we propose to present this homogeneous approach and to focus on the main results and performances over sea ice regions.