SMAP Soil Moisture Product Validity in Heterogeneous Irrigated Regions

In this study, soil moisture (SM) products from the NASA Soil Moisture Active Passive (SMAP) mission are assessed for their validity in heterogeneous, irrigated agricultural regions. SMAP products at 36 km and at enhanced 9 km resolution are compared with in situ SM data from an operational farm in Florida during the 2018 and 2019 growing seasons for field corn and peanuts. SMAP has a strong positive SM bias which may be caused by unrealistic vegetation water content (VWC) values being used in the SM retrieval algorithm. To determine whether higher spatial resolution VWC information can improve the SM retrieval algorithm, Sentinel-1 derived VWC will be used to form a SM regression model. The model will be calibrated on a Florida research site and tested on the study farm.