Using a simple threshold retracker on SAR and LRM data from CryoSat-2 it is seen that the SIRAL radar altimeter shows great potential for height estimation over land and inland waters. Differences between heights from the SRTM DEM and the retracked heights were less than 1m for Lake Vättern in Sweden, which is well within the error range of 16m for SRTM. However, some difficulties where encountered, such as snagging due to bright targets off-nadir, as well as an occasional inability of the altimeter to adjust the window delay to the underlying terrain. It was also found, that classification of waveforms over land and inland waters is challenging. Therefore, using a well resolved river and lake mask and focusing on small test regions is recommended until radar altimetry over land and inland waters is fully understood.
Proc. ‘esa Living Planet Symposium 2013’, 2013
Radar altimetry; SAR; River and lake levels; Land hydrology retracking