In May 2004 a field campaign was conducted to study transport and diffusion over the central Washington DC area. A number of in-situ and remote sensing meteorological instruments were deployed to measure atmospheric stability and wind flow patterns ranging from building- to urban-scale. This study focuses specifically on the observations made by two coherent Doppler lidars. The two lidars were deployed approximately 5 km apart, and performed overlapping volume scans during the most of the field experiment. The region of overlap encompasses an area that includes the Washington DC mall and nearby Potomac river. Dual-Doppler lidar data are analyzed in order to investigate the 3-dimensional flow structure over the central Washington DC area.

We first present an overview of the observations derived from the lidars over the course of the two week experiment, including 5 IOPs. Estimates of boundary layer height derived from lidar backscatter data and from radiosonde temperature soundings are compared. We also compare estimates of mean wind profiles derived from VAD analyses of each of the lidars. Next, we present the results of the dual-Doppler analysis during the night of 5-6 May 2004. On this night, a frontal passage occurs at approximately 21 UTC. Following the front, colder air advects in and stable conditions prevail until the next morning. The dual-Doppler analysis provides a detailed picture of the structure and evolution of the three-dimensional flow during this period.