Optical properties and seasonal distribution of aerosol layers observed by lidar over Jinhua, southeast China

To explore the vertical distribution of the aerosol optical parameters over Jinhua City, southeast China, a Dual-wavelength Mie Polarization Raman Lidar (DMPRL) system was operated to obtain the atmospheric backscattering signals from June 2013 to May 2014. Profiles of aerosol occurrence frequency and aerosol optical parameters, including backscattering ratio, particle depolarization ratio, and color ratio, were retrieved from the lidar signals. The cases with a cloud base below 6 km and profiles on rainy days were eliminated. The multi-layer vertical aerosol structure was found in Jinhua area and the altitude-resolved optical properties varies with seasons. In autumn, winter and spring, the aerosol layer occurrence frequencies were higher than summer at 3–6 km, especially in spring. The mean particle depolarization ratio at 4–6 km exceeded 0.1 in autumn, winter, and spring, whereas it was <0.05 in summer. Aerosol with high color ratios appeared at 0–2 km in autumn. The analysis of one-year backward trajectories exhibits a dust dominating aerosol layer at 4–6 km in autumn, winter, and spring, a partially sea salt dominating aerosol layer at 0–2 km in autumn and a partially dust aerosol layer at 0–2 km in winter. Six cases were used to study the influence of aerosol advection and local sources vertical aerosol properties distribution. Through our analysis, aerosols at different altitudes are influenced by different sources, which are important for understanding the spatiotemporal characteristics of aerosol layers over Jinhua. The vertical distribution of aerosol properties in Jinhua area is affected by locally emitted aerosol , transported dust and ocean aerosol.