Monitoring Rivers and Lakes with a Ka-Band Interferometric Radar Altimeter : An Assessment of the Performances
Enjolras, V1; Rodriguez, E2
1Thales Alenia Space; 2NASA JPL

Profiling nadir-pointing radar altimeters are not capable of providing adequate space-time sampling of global surface water, independently of their intrinsic accuracy. To overcome this limitation, we present an instrument concept, the Ka-band Radar Interferometer (KaRIN), which is able to provide the appropriate space-time sampling with a height and slope accuracy suitable to resolve topographic signatures land hydrology applications.

The KaRIN instrument builds on the interferometric SAR concept demonstrated by the NASA Shuttle Radar Topography Mission (SRTM), and the Wide-Swath Ocean Altimeter concept. Two major modifications are made to these systems to achieve the desired performance. The spatial sampling requirement implies full synthetic aperture processing. Besides, achieving the desired height and slope accuracy with a realizable spaceborne instrument requires using a Ka-band radar at near nadir incidence.

The sampling of river discharge requires an approximately weekly revisit time, an ability to image water bodies with a spatial resolution of 100m, a height accuracy better than 10cm and a slope accuracy of 10 µrad. To validate the science performance of the system we have implemented a Virtual Mission simulation and examined the measurement performances over a variety of water scenes, including rivers Meuse and Lena. Simulations and related results will be presented. They demonstrate the ability of such a system to meet continental waters observation requirements.


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