The Soil Moisture-Atmosphere Coupling Experiment (SMACEX) was conducted in the Walnut Creek Watershed near Ames, Iowa over the period from June 15-July 11, 2002. A main focus of SMACEX was investigating the interactions between the atmospheric boundary layer, surface moisture and vegetation states. The Lidar collected data over fields of soybeans and corn, with mutually supporting measurements by the NRC Twin Otter atmospheric research aircraft, the Utah State University Piper Seneca remote sensing aircraft, elastic Lidars, and an array of eddy covariance towers in the nearby fields. The aircraft and lidar will provide a high resolution mapping of the evaporation rate over the fields and the changes between them. High-resolution water vapor concentrations will also allow us to examine the response of the atmosphere to the change in surface roughness and canopy.

During the field campaign, the lidar operated daily during daylight hours. During the first 2-1/2 weeks of the experiment, there were no precipitation events in the project area. Nevertheless, there was vigorous growth by the dominant crops of corn and soybeans, creating large changes in surface roughness and canopy contribution to evapotranspiration. This paper will provide a mapping of the evaporative fluxes that existed during the field campaign, with a comparison to the topology of the local area. The comparison will be made over an extended dry-down period as the corn grew rapidly.