12th Conference on Interactions of the Sea and Atmosphere


SAR Measurement of two dimensional Sea Surface Elevation Fields on a global Scale

Susanne Lehner, German Aerospace Center, Remote Sensing Technology Center, Wessling, Germany; and J. Schulz-Stellenfleth, J. C. Nieto Borge, and W. Rosenthal

Spaceborne Synthetic aperture radar are capable to provide simultaneous high resolution measurements of ocean waves and near surface wind fields on a global scale. Due to their all weather capability SAR is still the only instrument providing directional information on waves and mesoscale information on wind fields on a continuous basis.

In the present study a reprocessed data set of complex SAR images acquired by the European Remote Sensing satellite ERS-2 is used to estimate different wave and wind parameters relevant for air sea interaction processes. The images are taken every 200 km along the track with a size of 10 by 5 km and a resolution of 20 m.

A new method is presented to derive two dimensional sea surface elevation fields from complex SAR data. The method allows to analyze the wave field in more detail than conventional SAR wave measurement techniques, which only estimate the wave spectrum, i.e. second order moments of the wave field. The technique provides parameters like maximum to significant wave height ratios, wave steepness or the probability of wave breaking. The parameters are compared with classical theory, e.g. on exceedance probabilities for wave heights. Global maps of the new parameters are presented.

Wind speed and statistics on spatial wind speed variability is derived from calibrated SAR images. Correlations between estimated wind and ocean wave parameters like. e.g. steepness and wind stress are analyzed.

Apart from global statistics different case studies like the Hurrican FRAN, observed in the North Atlantic in 1996 are presented.

Session 10, Active Remote Sensing of air-sea interaction
Thursday, 13 February 2003, 1:30 PM-4:15 PM

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