Bistatic scattering of global positioning system signals from Arctic sea ice.

摘要

This work evaluates the potential use of scattered Global Positioning System (GPS) signals for the retrieval of information related to the presence and condition of the Arctic sea ice cover.; Although the combined satellite microwave record over the period 1979 to 2006 indicates that the Arctic sea ice extent has declined for every month, evidence for accompanying reductions in ice thickness has been hampered by the poor separability of the sea ice categories based on available active and passive measurements.; Using data collected from an airborne platform flying over the Beaufort, Bering and Chukchi Seas during the month of March in 2003, a geophysical model function is fit to scattered GPS waveforms to estimate parameters such as the L-band dielectric permittivity of the surface and its large scale roughness. These products are compared satisfactorily against independent measurements of roughness provided by a LIDAR surface profiler and a reference classification of sea ice types obtained from the simultaneous analysis of polarimetric brightness temperatures at 11, 19 and 37 GHz, C-band radar backscatter and visible/infrared imagery. We find that the ability of GPS derived permittivities to delineate the extent of the sea ice cover and separate the thin ice classes matches that of the currently operational radiometers, and that GPS derived roughness measurements provide improved separability of the thick ice classes, along with additional information about the deformation processes that affect the Arctic cover.