Hotspots for Soil Moisture Retrieval Failure across Continental USA

Soil moisture is the key link between climate fluctuations and vegetation dynamics in space and time. In this work, an ecohydrological framework is proposed to understand soil moisture mechanisms underlying the climate-soil-vegetation interactions. This framework is proposed for Level I Ecoregion (15) and Level II Ecoregion (50) across continental USA. A spatio-temporal variability in climate-soil-vegetation interactions across all ecoregions, and its influence on Radiative Transfer Model (RTM) to retrieve soil moisture is highlighted. These interactions are analyzed across all ecoregions, and presented through a probability distribution function (PDF). We observe soil moisture dynamics to play a key role in variability of climate-soil-vegetation interactions at all spatio-temporal scales. Our analysis shows that, soil moisture dynamics enhance both mean and variance of soil-vegetation coupling, and these regions are deemed as "hotspots". As these hotspots also fail to achieve the soil moisture retrieval accuracy, and this can be attributed towards inefficacy in radiative transfer model. These hotspots are categorized accordingly to yield ecoregion specific scaling function to RTM for retrieving soil moisture. A relationship is established between these hotspot regions and its correspondence with evapotranspiration. Thus, this work presents quantifiable measures of climate-soil-vegetation interactions, discussing hydrologic mechanisms underlying basic ecologic patterns.