The CTOH develops specifics methods and processing applied to the continentals surfaces in particular for the cryosphere.
- ICE-2 retracker
- Altimetric data collected over continents are usually processed and optimized for ocean surfaces which restrained their use for continental applications. With the introduction of radar altimetry applications over the ice sheets, a new retracking procedure was developed, the so called ICE-2 retracker. It has been designed to process altimeter waveforms obtained over most of the non-ocean surfaces. This technique was first applied with success to the ERS altimeter data (Legresy & Remy, 1997; Remy et al., 1999; Vinay et al., 2002). This processing has been now included directly in the ENVISAT radar altimeter ground segment, which enables retracked data to be delivered to the users for continental surface applications.
- Quality Assessment
- Ice validation for Antarctic and Greenland continents. We investigate the stability and reliability of different corrections for the altimetric measurements. Currently, a validation chain is already developed specifically to the cryosphere (ICE validation). The products of that validation are available cycle by cycle.
- Geographical and echo corrections
- A method has been developed at LEGOS to survey along track. This method has the advantage to avoid the ascending/descending difference in echoing and also to lead to around 100 times more measurements available to survey the evolution. It also helps to look at the time evolution of the ice sheet surface at small scales of the order of few km in regional or local studies. Using this method, both the error due to bad repeatability (geographical) and the error due to change in snow pack properties (echo) are calculated and apply to the height measurement.