An Assessment of a Ka-Band Radar Interferometer Mission Accuracy Over Eurasian Rivers

The Water Elevation Recovery satellite mission is dedicated to the determination of land surface water extent, elevation, and slope using a Ka-band radar interferometer (KaRIn) as its primary instrument. Determining these parameters to the accuracy desired for hydrologic applications is challenging. The scientific objectives of the mission have been set up to 10 cm for the height budget and 10 murad (1 cm/1 km) for the slope budget. In this paper, we implement a Virtual Mission simulation and use it to examine the measurement performances for three case studies in Europe: a relatively small river such as the Meuse in Northern Western Europe, the Lena river in Russia, one of the major Siberian rivers, and Lake Leman in Western Europe. We simulate KaRIn data with the associated instrument and geophysical error sources and implement ground processing techniques to go from the original raw data to science data. We examine the impact of external errors in detail and implement calibration techniques that rely on the use of ancillary topographic data, such as the Shuttle Radar Topography Mission digital elevation model (DEM). We find that the impact of external errors can be reduced to a few centimeters. The random error budget can also be reduced below 10 cm by means of appropriate processing. The scientific requirements of the mission are shown to be met for all cases.