RETRIEVAL OF GEOPHYSICAL PARAMETERS FROM RA-2 ENVISAT USING THESOUTHAMPTON OCEANOGRAPHY CENTRE RETRACKING ALGORITHM

摘要

The Southampton Oceanography Centre oceanrnretracker, initially designed for ERS-1 altimeter data,rnhas been updated for RA-2 Envisat waveform data, inrnorder to be used to retrieve some geophysicalrnparameters such as, the significant wave height, thernbackscatter power and the range. The algorithm, basedrnon the Maximum Likelihood Estimation, is capable ofrnobtaining those parameters, assuming both linear andrnnon-linear conditions. The use of the non-linear case,rnallows us to estimate additional parameters, such us thernskewness, which relates to the nonlinearity of the wavernfield (I.e. peakier crests/flatter troughs) and a crossskewness term, with no clear physical significance. Inrnthe present work, we have retrieved the significant wavernheight and the range from RA-2 Envisat 18 Hzrnwaveforms using the SOC ocean retracker. First resultsrnshow that the linear MLE model retrieves parametersrnconsistent with those in RA-2 SGDR records. This workrnis part of an ESA study for the exploitation of thernEnvisat radar altimeter individual echoes and S-bandrndata for ocean, coastal zone, land and ice/sea-icernaltimetry (RAIES).