Soil Moisture Across Scales – Variability, Persistence, and Controls.

Soil Moisture Across Scales – Variability, Persistence, and Controls Binayak P. Mohanty Soil moisture is a key state variable of the hydrologic cycle. It plays a significant role in many hydrological, meteorological and other natural processes in the land-atmosphere continuum. In the past two decades we have conducted several field campaigns to better understand the underlying processes controlling the spatio-temporal variations of soil moisture using multiple ground, air, and space-borne sensors. In this effort, we will present characteristics spatio-temporal variabilities, time stability, as well as their geophysical controls at different measurement support scales (point-scale, airborne, to space borne remote sensor footprints) in different hydro-climatic regions. The data used in the analyses consist of in-situ and passive microwave remotely sensed soil moisture data from Southern Great Plains hydrology experiments 1997 and 1999 (SGP97 and SGP99) conducted in Little Washita (LW) watershed, Oklahoma, and Soil Moisture Experiments 2002 and 2005 (SMEX02 and SMEX05) in Walnut Creek (WC) watershed, Iowa. Results show that in both the regions soil properties (i.e., percentage silt, percentage sand, and soil texture), and topography (elevation and slope) are significant physical controls jointly affecting the spatio-temporal evolution and time stability of soil moisture at both point- and footprint-scale. We will discuss the implications of our findings in soil hydrology, land-atmosphere interaction, and other applications.