Retrieving soil moisture for non-forested areas using PALS radiometer measurements in SMAPVEX12 field campaign

In this paper, soil moisture retrievals of surface soil moisture was investigated using L-band brightness temperature under diverse conditions and land cover types. The study focused on the PALS (Passive Active L-band System) radiometer data collected during the SMAPVEXI2 (Soil Moisture Active Passive Validation Experiment 2012) field experiment which took place in southern Manitoba, Canada in 2012. The experiment domain covers croplands with high clay content as well as croplands and grasslands with sandy soils. A retrieval algorithm was parameterized for these specific land types. The formulation of the retrieval algorithm is based on a traditional surface scattering assumption. Based on this data set we found that for the clayey croplands the surface scattering assumption is inadequate, and that the algorithm needed significant tuning for the sandy soils. Empirically-based parameters for retrieving soil moisture under these conditions were developed. We also applied the parameterized algorithm to the retrieval of soil moisture for the entire experiment domain. We found that the use of sub grid modeling improves the retrieval performance to a satisfactory level despite the challenging land types encountered. (C) 2016 Elsevier Inc. All rights reserved.