Migration of radar altimeter waveform data

Abstract

Wingham [1993] demonstrated that migration of radar waveforms appears to improve the images of ice sheet topography. We examine whether this qualitative improvement might lead to quantitative benefits in measuring ice sheet elevation change. We find, instead, that estimates based on migrated waveforms at cross-over points are degraded relative to unmigrated waveforms. Lack of cross-track data, which would allow true 3D migration, and migration "noise" related to the Kirchoff algorithm are likely contributors to the degradation. Additionally, lack of phase information in radar waveforms degrades the result. This problem is not encountered in seismic applications of migration and is a limitation of the current generation of radar altimeter data. We have not investigated whether other quantitative benefits may be derived from migrating altimeter waveforms. For example, improved resolution of smaller scale topography in migrated data may lead to better quantitative understanding of ice sheet dynamics.