Multi-Frequency Retrieval of Soil Moisture Profiles from L- and P-Band Active Microwave Observations

This thesis develops a way to measure how much water is in the soil down to root depth, at field-scale detail. It combines two kinds of satellite radar (L-band and deeper-penetrating P-band) and tests with a variety of models at each. The study shows common models work well at L-band but break down at P-band, where signals come from below the surface. A new multi-frequency method, using ensembles and short time-series, combines the strengths of both bands to deliver stable estimates. Across crops and bare soil it keeps errors typically under about 6% and provides useful information up to around 40 cm depth.