Forward and inverse signature modeling for congelation ice

Thin congelation sea ice in Arctic leads is an important remote sensing target for geophysical purposes, and can be successfully simulated in a laboratory environment. The vertical profile of permittivity in such ice directly controls not only the reflection coefficient of the ice, but also backscattering, when such scattering is due to roughness at the air/ice interface. The authors summarize a forward signature model showing how this arises, and summarize recent evidence supporting the model, namely 24-cm wavelength polarimetric SAR observations of thin sea ice in the Beaufort Sea. The model links inference of the permittivity profile in congelation ice (or simple properties of that profile such as ice thickness) from polarimetric backscattering observations to the classical one-dimensional problem of profile estimation from reflection data. Thus the authors consider estimation of the complex permittivity profile in a lossy medium such as sea ice from vertically- and horizontally-polarized reflection data within some range of frequencies. They show that both the real and imaginary parts of the permittivity can be estimated using such reflection data at single angle of incidence. They present a layer-stripping-like algorithm to accomplish this