The wide swath ocean altimeter: radar interferometry for global ocean mapping with centimetric accuracy

The recent Shuttle Radar Topography Mission (SRTM) has demonstrated the capability for global interferometric topographic mapping with meter level accuracy and 30 meter spatial resolution. The next challenge in radar interferometry is the measurement of ocean topography: the global characterization of ocean mesoscale eddies requires global coverage every 10 days, with centimetric height accuracy, and a spatial resolution of 10-20 km. We have developed an instrument concept that combines a conventional nadir altimeter with a radar interferometer to meet the above requirements. In this paper, we describe the overall mission concept and the interferometric radar design. We also describe several new technology developments that facilitate the inclusion of this instrument on a small, inexpensive spacecraft bus. These include ultralight, deployable reflectarray antennas for the radar interferometer; a novel five frequency feed horn for the radiometer and altimeter; a lightweight, low power integrated three frequency radiometer; and a field programmable gate array-based onboard data processor. Finally, we discuss recent algorithm developments for the onboard date processing, and present the expected instrument performance improvements over previously reported results.