2007 Annual Report 1a.Objectives (from AD-416) To support the mission of the Duke Helicopter system, make measurements of the spatial variability of the boundary layer, provide column aerosol measurements via the solar photometers. 1b.Approach (from AD-416) 1. Continuous boundary layer height, entrainment zone width at the stationary lidar location. 2. Continuous cloud height, thickness, opacity and reflectivity measurements at the stationary lidar location. 3. Estimates of the areal sensible heat flux. 4. Measurements of the variability of the boundary layer height with position. 5. Measurements of aerosol properties from the solar photometers. 6. Estimates of the boundary layer A parameter. 3.Progress Report This report serves to document the progress under a Specific Cooperative Agreement between the University of Iowa and ARS. Additional details of the research can be found in the parent project 3625-11630-002-00D, Emission and Dispersion of Air Quality Constituents from Agricultural Systems. Cloud affects on surface conditions affects the energy balance and thus the sensible and latent heat fluxes over a surface. There are limited observations on the vertical conditions that exist above flux tower measurements of sensible and latent heat that can be used to evaluate how changes in cloud cover can affect these fluxes. An experiment was conducted for six weeks in central Oklahoma during June and July to evaluate these interactions as part of a larger surface energy balance experiment. The observations have been completed and data analyses are being conducted with the goal of completing the reports by the end of 2007. Weekly telephone and email exchanges were held prior to the experiment and daily discussions were held during the experiment.