Laser remote sensing for characterization of planetary boundary layer properties

Summary form only given. The lowest layer of the atmosphere is, due to the friction of the moving air masses with the earth surface, very turbulent. The mixing of exhaust fumes and dust and a lot of chemical reactions take place. For that reason, 3D data of trace gas concentrations as well as aerosol properties and parameters of the dynamics are absolutely necessary for the understanding of the processes, model initialization, evaluation and pollution prediction. Laser remote sensing is one of the favorite methods to get measurement of time series with a reasonable resolution in time and space. However, the fast dynamic causes problems in the evaluation of laser remote sensing signals. Elastic backscattering, which is normally used as a signal source for differential absorption measurements, also uses Rayleigh scattering and scattering on aerosols. The backscatter intensity depending on aerosols varies significantly in time. For differential absorption lidar (DIAL) measurements in particular, we must average some hundreds or thousands of shots to get an adequate signal to noise ratio. The influence of short time fluctuations to the average causes major problems in the retrieval of trace gas concentration profiles, and we lose information about short time fluctuations and dynamics. To overcome these problems, we decided to combine fast sampled elastic scattering signals and averaged Raman signals to bring out the dynamics, aerosol size distribution, the extinction and the ozone concentration.