Ice-sheet elevations from across-track processing of airborne interferometric radar altimetry

• Main Authors: Hawley, RL, Shepherd, A, Cullen, R, Helm, V, Wingham, DJ
• Format: Article in Journal/Newspaper
• Language: English
• Published: AMER GEOPHYSICAL UNION 2009
• Subjects: Altimeter; Interferometry; Ice; Greenland; Antarc*; Antarctica; Ice Sheet
• Online Access: https://discovery.ucl.ac.uk/id/eprint/75804/1/2009GL040416.pdf; https://discovery.ucl.ac.uk/id/eprint/75804/

Interferometric Radar Altimeters (IRA's) use dual receive antennas to overcome one of the spatial limitations of pulse-limited altimeters. In a conventional IRA measurement, the range and across-track direction of a scatterer are determined using the phase difference between the antennas. We demonstrate a method of determining multiple elevation points across a swath orthogonal to the instrument ground track in regions of steep terrain, such as ice-sheet margins. We use data from an airborne IRA (a prototype of the CryoSat-2 instrument), and compare the results to simultaneous Airborne Laser Scanner (ALS) observations. This application results in a 75-fold increase in measurement density compared to conventional radar altimetry. Along a similar to 2.5 km ground track, the RMS departure between the IRA- and ALS-derived measurements was 1.67 m. Based on our result, although our approach is limited to areas of relatively steep slope, a 25- to 75-fold increase in elevation measurements could be achieved in coastal regions of Antarctica and Greenland with similar processing of CryoSat-2 data.