Microwave Vegetation Index Derived from Multi-angular Passive Microwave Observations at L-Band

Knowledge of the variability of microwave signatures of vegetation and roughness are necessary to separate these influences from those of soil moisture for remote sensing applications to global hydrology and climate. Conventional, vegetation indices are often limited by the effects of atmosphere, background soil conditions. The Soil Moisture and Ocean Salinity (SMOS) satellite will provide global multi-angular microwave brightness temperature observations at L-band, in dual polarization and multi-angles. Through the analysis of the simulations by the advanced integral equation model (AIEM), we found that the polarization difference for the bare surface emission signals at different view angles can be well characterized by exponential function with parameters that are dependent on the pair of view angles to be used. The developed microwave vegetation index is independent of soil surface emission signals and can provide new vegetation information since the L-band microwave measurements are sensitive to the properties of the overall vegetation. This method provides a new opportunity to monitor vegetation cover and retrieve soil moisture minimizing the effect of vegetation for SMOS applications.