Ku-Band Radar Altimeter Surface Wind Speed Algorithm

Abstract

A surface wind speed retrieval algorithm from Ku-band radar altimeter backscatter coefficients is presented. It was derived using two-months of ENVISAT altimeter backscatter data collocated with ECMWF model and in situ wind speeds and was extensively verified for ENVISAT, ERS-2, and Jason-1/2 against model and in situ wind data. The algorithm performs better than the two-parameter (backscatter and significant wave height, SWH) algorithms of Jason-1/2. The success of the current algorithm raises a question regarding the usefulness of SWH alone as a second parameter for retrievals. It is argued that SWH alone is not the proper choice to represent the sea-state conditions.

Keywords:

• Atmospheric model
• backscatter
• ECMWF
• Envisat
• ERS-2
• Jason radar altimeter
• retrieval algorithm
• significant wave height
• verification
• wind speed

Acknowledgements

This work was carried out with the European Space Agency (ESA) support through ESA contract No. 17585 (Global Validation of ENVISAT Data Products). Special thanks are due to Peter Janssen, Jean-Raymond Bidlot and Hans Hersbach for support and valuable discussion. Comments and suggestions from the reviewers are highly appreciated.