Measuring Surface Water Level and Slope Using a Near-Nadir Kaband Radar Interferometer

Inhalt:
Conventional radar altimetry has been successful in retrieving water level measurements at altimeter crossings with an accuracy of 10 cm to 20 cm. Although promising, this measurement accuracy is insufficient to provide global monitoring of fresh water bodies, as has been proposed by the WatER (Water Elevation Recovery) mission, for instance. In this paper, we examine in detail the error sources that a near-nadir synthetic aperture radar interferometer, such as the KaRIN instrument proposed to meet the WatER requirements, will be subject to and demonstrate that with appropriate calibration techniques, measurements of river stage with an accuracy of approximately 5 cm and river slope with an accuracy of 1 cm/km can be obtained. In the first part, we examine the main error contributors to the height measurements and quantify the expected magnitude of the errors.