Benchmarking a Soil Moisture Data Assimilation System for Agricultural Drought Monitoring

Agricultural drought is defined as a shortage of moisture in the root zone of plants. Recently available satellite-based remote sensing data have accelerated development of drought early warning system by providing continuous soil moisture information in space and time. Nonetheless, the shallow sensing depth (top few cm) and uncertain accuracy of currentlyavailable satellite soil moisture retrievals necessitated the integrating hydrologic models and surface soil moisture observations through data assimilation techniques to obtain more accurate root zone soil moisture estimates. Although a number of previous studied have demonstrated the benefits of soil moisture data assimilation system, relatively little is known about the relative merits of particular retrieval, modeling and/or data assimilation strategies. In particular, it remains unclear what level of complexity and/or nonlinearity is appropriate for each of these components.