A theory for near-normal incidence microwave scattering from first-year sea ice

A theory is presented to explain near-normal incidence microwave scattering from first-year sea ice. The theory is based upon the hypothesis of an abnormal number of relatively large (in terms of wavelength) flat areas on the surface which are all at the same elevation relative to mean sea level. These flat areas are assumed to be randomly located circular spots with random radii. The incoherent power scattered by these equiheight flat areas is a result of their random transverse location while the coherent scattered power is a consequence of their equal elevation. The incoherent power is found to vary as the average number of flat spots per unit area while the coherent power varies as the second moment of the number per unit area. Application of this theory to typical radar altimeter data produces parameter estimates which are in reasonable agreement with the available surface truth. Finally, it is conjectured that this model may also explain certain anomalous scattering data obtained from other types of terrain and planetary surfaces.