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SMEX04
In much of the interior of the North American continent, summer precipitation is a dominant feature of the annual cycle. Surface boundary conditions play an important role in initiation and maintenance of the North American Monsoon System (NAMS), which controls summer precipitation over much of this region. Understanding these processes is a focus for the North American Monsoon Experiment (NAME) (http://www.joss.ucar.edu/name/) . A working hypothesis of NAME is that among the land surface antecedent boundary conditions that control the onset and intensity of the NAMS is soil moisture. The influence of the land surface is relayed through surface evaporation and associated surface cooling (dependent on soil moisture), terrain, and vegetation cover. Soil moisture and, in particular, surface wetness, can change dramatically after heavy rain events. Increased soil moisture after precipitation promotes evapotranspiration between storm events. This may contribute to enhanced convection and further precipitation. http://hydrolab.arsusda.gov/smex04/