Extraction of surface currents of solitary internal waves from synthetic aperture radar data

Abstract

Interaction between surface waves and horizontally varying surface currents produce variations in sea surface roughness which can be observed by a synthetic aperture radar (SAR). An inversion model is developed to extract surface currents from SAR images. This data inversion is based on iterative fitting of observed SAR data to forward models of wave-current interaction, radar scattering, and SAR imaging. The inversion model is applied to SAR measurements of solitary internal waves in the New York Bight during the SAR Internal Wave Signature Experiment (SARSEX) (Gasparovic et al., 1988). The surface currents of internal waves thus extracted are compared with in-situ measurements. A spaceborne SAR can provide all-weather, day-night imagery of the ocean with a swath of /spl sim/50 km and a spatial resolution of <20 m. The ability to extract accurate surface currents from SAR images provides a cost-effective means for obtaining surface current measurements over a wide area. This technique is especially useful when areas are imaged frequently by the sensor, such as about once a day for NASA's Lightweight SAR (LightSAR) currently in the planning stage.