Observations and theory of polarimetric backscatter from snowcover at 35, 95 and 225 GHz

This dissertation presents 35, 95 and 225 GHz polarimetric backscatter data from snowcover. It compares measured backscatter data with detailed in situ data measurements of the snowcover including microstructural anisotropies within the snowpack. Observations of radar backscatter at 35, 95 and 225 GHz were made during melt-freeze cycles, and measurable differences in the normalized radar cross-section (NRCS) between older metamorphic snow and fresh low density snow were observed. In addition, our polarimetric measurements show that the average phase difference between the co-polarized terms of the scattering matrix, $S\sb{vv}$ and $S\sb{hh}$, is nonzero for certain snow types. These measurements are explained by the effects that the microstructure of the snow has on propagation within the snowpack. A simple vector radiative transfer model that includes the propagation effects is seen to predict the Mueller matrix for dry snowcover reasonably well