1a.Objectives (from AD-416)
Soil moisture has been observed using different methodologies; remote sensing using airborne/satellite platforms, intensive ground-based measurements during various field campaigns, and soil moisture monitoring networks. Soil moisture data from remote sensing are usually available at very low spatial resolution and only for a shallow soil depth. In contrast, ground-based and in situ point measurements can extend beyond the rooting zone but are difficult to extrapolate spatially. Reconciling these remote sensing and ground-based, especially in situ networks, each with a different extent, support, and spacing is of paramount significance in the development of robust methodology to predict shallow subsurface soil moisture, surface runoff, and ground water recharge at different spatial scales. This research would establish site specific and generic scaling relationships. This new knowledge would lead to higher spatial resolution information for hydrologic and agricultural decision making.
1b.Approach (from AD-416)
ARS soil moisture networks at four locations will be verfied for calibration and scaling issues through field experiments. Longer term records will be quality controlled and processed to watershed averages. These will be compared to soil moisture products from several alternative retrieval algorithms. Performance will be assessed using statistical and qualitiative criteria.
A long history of successful field experiments involving many soil moisture remote sensing techniques over ARS sites in Oklahoma offers the potential to understand how point scale process, as measured by ground sensors, can be used to understand how these relate to satellite-based observations. Cooperators at Texas A&M University are developing data bases and techniques for integrating these different approaches. ARS cooperators have focused on the aircraft results and have planned a series of aircraft-based experiments for irrigated agriculture that will complement other projects being conducted by NASA cooperators. Communication consisted of site visits, meetings, and data base development activities. This project will provide a significant step in demonstrating the feasibility of a satellite mission and validating near future missions of opportunity.