Lidar Measurement of Boundary Layer Parameters

Abstract

Atmospheric boundary layer air flows are organized by a variety of circulation patterns such as thermals, longitudinal roll vortices, and gravity waves. Studies of these structures are made difficult by the large range of spatial and temporal scales represented in these structures. Spatial scales vary from a centimeter for the smallest turbulent eddy to tens of kilometers for a cloud street circulation. Early morning thermals have typical dimensions which are smaller than 100 meters; during the the day these cells grow to sizes on the order of 2 kilometers. The lifetime of a typical cell ranges from a few minutes to the order of an hour. The overall structure of the boundary layer evolves with the diurnal cycle while the structures inside are swept rapidly along by the wind. While much has been learned about these circulations with aircraft and other traditional measurement techniques, active remote sensors such as radar and lidar are required to provide complete description of the evolving three dimensional structure.