Remote sensing of ocean wave spectra by interferometric synthetic aperture radar

THE two-dimensional power spectra of ocean waves are of great interest not only to oceanographers but also in practical applications such as wave forecasting, trans-oceanic ship routing, and design of coast and offshore installations. Remote sensing of ocean surface waves can be difficult using conventional synthetic aperture radar (SAR) techniques, but waves can be observed clearly by SAR in the interferometric configuration (INSAR)1,2. This improvement is due to the ability of INSAR to provide images of the local surface velocity field, in contrast to conventional SAR for which the imaging process is related indirectly to the complex modulation of the surface reflectivity by longer waves and currents. Here we show that INSAR can be used to obtain wavenumber spectra that are in agreement with power spectra measured in situ. This new method thus has considerable potential to provide instantaneous spatial information about the structutre of ocean wave fields.