Lidar vertical profiling of water vapor and aerosols in the Great Lakes Region: A tool for understanding lower atmospheric dynamics

Abstract

Results of a recently developed water vapor Raman lidar instrument at Environment Canada's Center for Atmospheric Research Experiments (CARE) are shown for selected days of summer and winter seasons. The basic components of the Raman water vapor lidar consist of a 30Hz, Q-switched Nd:YAG high-powered laser utilizing the third harmonic (355nm), beam steering optics, a 0.76m Cassegrain telescope and three detection channels to simultaneously observe the vertical profiles of aerosols, water vapor, and nitrogen from near ground up to 9.5km. By manipulating the inelastic backscattering lidar signals from the Raman nitrogen channel (386.7nm) and Raman water vapor channel (407.5nm), vertical profiles of water vapor mixing ratio (WVMR) are deduced, calibrated, and compared against WVMR profiles obtained from coincident and collocated radiosonde profiles. The average standard deviation, in the water vapor mixing ratio, is estimated to be less than 10% between the sonde and lidar measurements. In addition, comparisons between simultaneous WVMR profiles and aerosol profiles obtained from a simple aerosol backscatter lidar, also located at the CARE facility, provide insight into the complex dynamic mixing of the lower atmosphere and their subsequent impact on climate and air quality.