Land-atmosphere interaction research, early results, and opportunities in the Walnut River Watershed in southeast Kansas: CASES and ABLE

This paper describes the development of the Cooperative Atmosphere Surface Exchange Study (CASES), its synergism with the development of the Atmospher e Boundary Layer Experiments (ABLE) and related efforts, CASES field progra ms, some early results, and future plans and opportunities. CASES is a gras sroots multidisciplinary effort to study the interaction of the lower atmos phere with the land surface, the subsurface. and vegetation over timescales ranging from nearly instantaneous to years. CASES scientists developed a c onsensus that observations should be taken in a watershed between 50 and 10 0 km across; practical considerations led to an approach combining long-ter m data collection with episodic intensive field campaigns addressing specif ic objectives that should always include improvement of the design of the l ong-term instrumentation. In 1997, long-term measurements were initiated in the Walnut River Watershed east of Wichita, Kansas. Argonne National Labor atory started setting up the ABLE array. The first of the long-term hydrolo gical enhancements was installed starting in May by the Hydrologic Science Team of Oregon State University. CASES-97, the first episodic field effort, was held during April-June to study the role of surface processes in the d iurnal variation of the boundary layer, to test radar precipitation algorit hms, and to define relevant scaling for precipitation and soil properties. The second episodic experiment, CASES-99, was conducted during October 1999 , and focused on the stable boundary layer. Enhancements to both the atmosp heric and hydrological arrays continue. The data from and information regar ding both the long-term and episodic experiments are available on the World Wide Web. Scientists are invited to use the data and to consider the Walnu t River Watershed for future field programs.