Analysis of the potential of the Ku-band Gamma Portable Radar Interferometer for sea ice information extraction.

Abstract

Radar remote sensing is a key technology for monitoring sea ice. In this regard, passive microwave and Synthetic Aperture Radars (SARs) are the most important sensor types. This technology has been used for sea ice applications for four decades, but there are still many uncertainties related to sea ice monitoring by SAR. Some of these may be solved by multi-sensor observations, in which case other sensors provide complimentary information to help with the interpretation of SAR images. In this thesis I investigate the possibility of using a Gamma Portable Radar Interferometer (GPRI) to further our understanding about sea ice in the arctic.

This thesis investigates the potential of mapping sea ice topography using the interferometric mode of the radar system and the potential of mapping a sea ice drift field from time series of GPRI-observations. The sea ice topography mapping is shown to be unobtainable from the interferometric mode due to the difficulties experienced when trying to correct for the flat earth phase. A back-up solution is proposed where the radar shadow of a specific feature is used to estimate the height of the feature and the result is of the expected magnitude for sea ice in that area. The thesis also shows how to estimate sea ice drift for succeeding images taken from a time lapse series. The estimated ice drift is shown to be accurate for areas where a lot of structure and edges are present, and poorer for areas where the ice floes are distributed more separately from each other.

This thesis also performs SAR vs. GPRI comparisons to evaluate to which degree SAR images can be used to validate features found from a coherent radar-system like the GPRI-system.