The DOE ARM/CART Program collaborated with the Southern Great Plains 1997(SGP97) Hydrology Experiment, a joint USDA-NASA initiative in Oklahoma and extreme southern Kansas over the one-month period of June 18 - July 17, 1997. The objectives of SGP97 were: to examine the estimation of surface soil moisture and temperature using remote sensing at a hierarchy of scales; to examine the feasibility of estimating vertical profiles of soil moisture and temperature by combining in situ data, remote sensing of the surface, and modeling techniques; and to evaluate the influence of soil moisture on the local surface energy budget and the influence of mesoscale variability in the surface energy budget on the development of the convective boundary layer.
In support of these objectives, we present comparisons of soil moisture measurements and estimates from three different locations in Oklahoma during SGP97. Deployed instrument systems included heat dissipation sensors (SWATS and SHAWMS), and time and frequency domain reflectometry systems (provided by SGP97 participants), with a supporting program of gravimetric sampling. This data supports comparison of profiles of both matric potential and volumetric water measurements in wet and drying environments. Our ultimate goal is to understand the performance and capabilities of the different measurement systems, in order to separate natural variability (due to surface and subsurface inhomogeneities) from differences in measurement techniques (e.g., point measurements vs.layer measurements) and instrument performance under varying conditions (e.g., possible contact problems in shrinking clays during drying periods).