SIMULATING THE EFFECT OF SPATIAL VARIABILITY OF SOIL HYDRAULIC-PROPERTIES ON MICROWAVE BRIGHTNESS TEMPERATURE OVER A CORN FIELD

Spatial variability of L-band (21 cm wavelength) microwave brightness temperature over a corn field, caused by spatial heterogeneity of soil hydraulic properties, is simulated by combining physically based models for microwave emission and for dynamics of soil water. The scaling theory is used for the spatial variability of soil hydraulic parameters, the scaling parameter being represented by a histogram corresponding to a log-normal frequency distribution. The mean and the standard deviation of brightness temperatures over a corn field are calculated as a saturated soil dries progressively under clear-sky conditions. Results are presented for two values for the coefficient variation (CV) of the scaling parameter, namely 0. 45 and 0. 65, which encompass the range of a few available field observations.