Using MIMICS to Model L-Band Multitemporal Backscatter Walnut Orchard Multiangle and From a

The Michigan microwave canopy scattering model (MIMICS) is used to model microwave scatterorneter data that were obtained during the August 1987 Eos Simultaneity Experiment. Dur- ing this experiment, truck-based scatterometers were used to measure radar backscatter from a walnut orchard in Fresno County, CA. Mul- tipolarized data were recorded for orchard plots of varying irrigation levels. MIMICS, a scattering model based on radiative transfer theory, is applied to model two data sets that were recorded during the exper- iment. These consist of a series of diurnal measurements, in which a single orchard plot was observed continuously over several 24-h pe- riods, and a multiangle data set, for which this same plot was observed at varying incidence angles. Ancillary data are used as inputs to MIMICS and the resulting modeled data are compared to the mea- sured backscatter. Results of the modeling analysis demonstrate ex- traordinarily good agreement with the measured data. Predictions for like- and cross-polarization backscatter configurations are found to be consistent with the scatterometer data, even though no free parameters have been used in the modeling analysis. MIMICS is shown to account for variations in canopy backscatter driven by changes in canopy state that occur diurnally as well as on longer timescales. The utility of using remotely sensed data for observing changes in plant and soil water sta- tus is demonstrated.