Atmospheric boundary layer dynamics and inversion technologies to obtain extinction coefficient profiles in the atmosphere from elastic lidar

A state of the art scanning multi-wavelength lidar (light detection and ranging) system has been built and deployed to measure atmospheric optical properties and to study atmospheric boundary layer (ABL) dynamics. Two field experiments were undertaken, the first in the context of the Baltimore PM Supersite experiment 2001/02, where it has been used to monitor sources and transport of aerosols and to study boundary layer processes in an urban environment. The second campaign was the Boundary Layer Field experiment Marshall 2001.; A new two-angle method (TALM) has been developed to determine the lidar solution constants and to obtain mean vertical profiles of atmospheric extinction from elastic lidar data. This calibration method requires lidar signals from at least one pair of elevation angles, averaged in time when operating the system in a permanent two-angle mode, or an arbitrary number of signal pairs, when a 2-D lidar scan is being processed. The method has been tested and applied to experimental data. TALM is a robust tool to invert the lidar equation and obtain profiles of atmospheric extinction.; An iterative procedure to compensate for systematic distortions in lidar signals is introduced. The approach is based on a combination of the slope method and TALM. It requires one to have lidar signals that are obtained close to the horizontal direction in clear and homogeneous atmosphere.; Lidar data have been collected during a haze event due to forest fire smoke, providing extensive observational details on the complexity of ABL processes. ABL flow was highlighted in an unprecedented fashion, as the smoke aerosols served as a natural tracer. Simultaneous measurement of aerosol characteristics at ground level gave the opportunity to link the flow in the atmospheric boundary layer to the land surface. For the prevailing atmospheric conditions the correlation between aerosol scattering measurements at the ground and the first available lidar bin at a height of 250 m was high (correlation coefficient R = 0.96), but decreasing with altitude.; During the Marshall 2001 campaign the lidar was used to obtain a time series of the structure of the atmospheric boundary layer. Continuous daytime series of vertical ABL profiles have been obtained from the elastic backscatter data, and simultaneously surface micrometeorological data were collected, which are used to investigate the influence of topography on ABL growth. Shifts in wind direction between sectors of different topography were found to have a strong impact on boundary layer height, yet surface layer similarity held for all time periods.; A comparative study of lidar, radar wind profiler and radiosonde data, revealed that the actual ABL height, obtained from radiosonde data of temperature and specific humidity, is biased if a strong residual layer is present. The only unambiguous matches of measurement occurred following rainfall events which cleared the ABL the previous day.