Soil Moisture Estimation at High Resolution Using Radar and Optical Imagery.

Soil moisture is recognized today as a key environmental variable at the interface between the atmospheric boundary layer and the vadose zone. It is critical for processes that divide rainfall in runoff and infiltration as well as partition incoming solar and long-wave radiation between sensible, latent, and soil heat fluxes. Consequently, soil moisture directly impacts weather and predictions of cloud cover, precipitation, air and soil temperature, and humidity. In addition, soil moisture controls primary production in terrestrial systems, wind and water erosion, soil chemical processes and pedogenesis. Yet, soil moisture today also appears to become the least defined parameter in the environmental sciences. Soil moisture of what: the top cm of the soil as measured by radar systems, the root zone as measured by optical sensors, the deeper vadose zone where gravity drives water flow, the top 40 cm of soil depth that determines trafficability? Soil physicists hold the knowledge and insights to formulate unambiguous soil moisture definitions applicable to solve a range of environmental problems. We will present our remotely sensed soil moisture data to present examples