Potential applications of 1-5 GHz radar backscatter measurements of seasonal land snow cover

Lower frequency microwave radar observations can help to measure the proper ties of snow cover on land by providing information about the soil-snow bou ndary condition. In this theoretical study, we examine the sensitivities of microwave radar measurements to soil and snow characteristics, and we comp are a simple model with previously published data. Depending on the surface roughness, copolarized ratios or single polarization time ratios of radar backscattering may be affected only by the incidence angle and the dielectr ic contrast at the soil-snow boundary. These measurements can reduce the nu mber of unknowns in any corresponding higher-frequency observations that ar e also affected by the lower boundary condition. The copolarized ratio is s ensitive, first of all, to the snow density, which offers the possibility o f measuring this parameter directly if a separate measurement of the soil t emperature from a passive microwave system is also available. The thermal i nsulation provided by snow cover can have a powerful effect on the soil-sno w boundary by altering the soil temperature and therefore changing the diel ectric contrast. Because the microwave response of snow cover is so sensiti ve to the conditions of the underlying frozen soil, it is important for fut ure ground truth campaigns that measure snow conditions to also collect dat a on the temperature, water content, and texture of the soil.