Evolution of turbulence in the boundary layer over Oklahoma City as observed by wind profiling radars

During July 2003, Pacific Northwest National Laboratory (PNNL) and Argonne National Laboratory (ANL) participated in the Joint Urban 2003 (JU2003) field measurement campaign in Oklahoma City. The overall goal of the field program was to gather data in order to better understand the flow of air through urban canyons and around urban centers and in order to evaluate the ability of numerical models to simulate that flow in detail. As part of the field campaign PNNL and ANL operated 915 MHz wind profiling radars approximately 2 km south and 5 km north, respectively, of the downtown core. The dominant wind direction during the field campaign was southerly. Thus, these systems provided a characterization of the boundary layer upwind and downwind of downtown for most of the month. In addition to extracting basic wind and temperature information from these data, we are also investigating changes in boundary layer turbulence as the air passed over downtown. In this paper we will compare dissipation rates extracted from these profilers as a function of wind direction and time of day. We compute the dissipation rate using recently developed techniques to extract this variable from wind profiling radars. Both systems were operated in a single five-beam mode with 60-m range gate resolution. The necessary spectral moments were identified using the NCAR Improved Moment Algorithm.