Radiobrightness signatures of energy balance processes: melt/freeze cycles in snow and prairie grass covered ground

The authors are developing physically based, one-dimensional heat flow models for snow and soil which, when linked to simple microwave emission models, will predict the temporal radiobrightness response to insolation and atmospheric thermal forcing. The authors use a soil temperature model to analyze the thermal infrared and spectral radiobrightness signatures of snow and grass covered ground undergoing melt/freeze cycles. The data were taken in January and February of 1993 during the first Radiobrightness Energy Balance Experiment (REBEX-1) near Sioux Falls, South Dakota, with horizontally polarized radiometers at 19.35, 37, and 85.5 GHz (SSM/I frequencies). The soil portion of the heat flow model is described and example soil diurnal temperature cycles are compared to those from REBEX-1. It is shown that the diurnal amplitude of the radiobrightness cycle exceeds that of the surface temperature cycle when freeze/thaw transitions occur