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In order to investigate the aerosol variability over the southwest region of Slovenia, an ultraviolet scanning elastic backscatter LiDAR was utilized to make the vertical scan for atmospheric probing. With the assumption of horizontal atmospheric homogeneity, aerosol optical variables were retrieved from the horizontal pixel data points of two-dimensional range-height-indicator (RHI) diagrams by using a multiangle retrieval method, in which optical depth is defined as the slope of the resulting linear function when height is kept constant. To make the data retrieval feasible and precise, a series of key procedures complemented the data processing, including construction of the RHI diagram, correction of Rayleigh scattering, assessment of horizontal atmospheric homogeneity and retrieval of aerosol optical variables. The measurement example demonstrated the feasibility of the ultraviolet scanning elastic backscatter LiDAR in the applications of the retrieval of aerosol extinction and determination of the atmospheric boundary layer height. Three months' data combined with the modeling of air flow trajectories using Hybrid Single Particle Lagrangian Integrated Trajectory Model were analyzed to investigate aerosol variability. The average value of aerosol extinction with the presence of land-based air masses from the European continent was found to be two-times larger than that influenced by marine aerosols from the Mediterranean or Adriatic Sea. [ABSTRACT FROM AUTHOR]

To understand the characteristics of atmospheric pollution in Xi'an, China, the vertical structure of aerosols and meteorological data (temperature and relative humidity) during atmospheric pollution processes were obtained and studied. Lidar and radiosonde data were used for analyses of atmospheric pollution. Polarization lidar was used to study the vertical distribution and optical properties of aerosols during haze and dust processes that occurred in 2015–2016. The planetary boundary layer height (PBLH) and types of aerosol particles were retrieved from polarization lidar. A case study shows that a low PBLH and complex vertical distributions of aerosols, temperature and relative humidity (RH) were the main structural characteristics of haze days. The backscatter coefficient exceeded 0.015 km−1·Sr−1, while the linear particle depolarization ratio was relatively small. A large depolarization ratio above the haze layer, which induces the existence of floating dust, was observed by polarization lidar. Compared with those of haze processes, the vertical aerosol and temperature distributions of dust processes were different. Statistical analyses of the PBLH, temperature inversion, RH and near-surface aerosol concentration were also presented. A lower PBLH, lower average lapse rate of temperature within the PBL, and higher RH were found when haze pollution occurred. An inversion at the top of the boundary layer aggravates ground pollution, while there is not always a temperature inversion when haze occurs in Xi'an. Together, a lower PBLH and lower average lapse rate of temperature weaken the vertical diffusion of pollutants. Decreased vertical diffusion should be the main reason for the formation and persistence of pollution in Xi'an. Increased RH was the catalyst for haze pollution. The aggravation of haze was usually accompanied by an increase in RH, and the decline of haze processes was also accompanied by a decrease or increase (>90%) in RH. • The simultaneous observations of aerosols and meteorological factors profiles in Xi' an, were performed. • The complex vertical distributions of aerosol, temperature and relative humidity were found in pollution process. • Little average lapse rate of temperature is the main reason for the decrease of vertical diffusion ability of pollutants. [ABSTRACT FROM AUTHOR]