Multi-incidence angle soil moisture retrieval using passive microwave data at L-band

THIS thesis investigates the potential of multi-incidence angle L-band measurements to enhance the retrieval process of near-surface soil moisture information from passive microwave data. In particular, it examines remotely sensed multi-angle observations collected over Australia by both airborne and spaceborne systems at varying spatial and temporal resolution. Initial work focussed on the adaption of one of the current state-of-the-art retrieval algorithms called L-band Microwave Emission of the Biosphere (L-MEB) to multi-angle measurements. Subsequently, the modified model was applied to three independent sets of field data to evaluate different aspects of the retrieval mechanism. Two out of the three available datasets were collected prior to the Soil Moisture and Ocean Salinity Mission (SMOS) launch in 2009. However, the third field experiment named Australian Airborne Cal/val Experiments for SMOS (AACES) was specifically designed for calibration and validation of SMOS. The design and realisation of this intensive field campaign, which was conducted twice in summer and winter, was a vital part of this Ph.D. The multi-incidence angle research included an initial assessment on the performance of specific model parameterizations by comparison with ground data. Further analysis focussed on partly synthetic studies on the accuracy of simultaneously derived model parameters at various angular groups and parameter combinations. Findings from the previous research were then tested on the newly available AACES dataset, which in turn was used to evaluate the performance of the spaceborne L-band sensor of SMOS. The findings from the synthetic study and the field measurements were compiled and ultimately aim at supporting a better understanding and utilization of multi-incidence angle observations for the purpose of large scale soil moisture mapping. <br> <br>