A simple algorithm for retrieval of the optical thickness at L-band from SMOS data

Vegetation indices are indicators for analyzing the properties of vegetation. The Normalized Difference Vegetation Index (NDVI) from optical remote sensing data is one of the most commonly used vegetation indices, which can exhibit the ecological characteristics of leafy materials, but lacks the ability to directly provide information on the woody materials. In this paper, we developed Microwave Vegetation Indices (MVIs) from the L-band Soil Moisture and Ocean Salinity (SMOS) data, which is an effective means to detect the information of branches and trunks. The theory of MVIs is derived from the tau-omega model. To minimize the influence from the uncertain soil surface radiation, a parameterized database was built by the Advanced Integral Equation Model (AIEM). We selected two incidence angles (40° and 50°) and combined them to compute the MVIs. A simple method to evaluate the L-band optical thickness efficiently based on the MVI b-parameter (MVI-B). The MVI optical thickness(MVI-τ) was compared with the optical thickness retrieved from SMOS(SMOS-τ), and the results showed that the overall pattern was very similar.