Characterization of columnar aerosol over a background site in Central Asia

Ground-based observational characterization of atmosphere aerosols over Central Asia is very limited. This study investigated the columnar aerosol characteristics over Issyk-Kul, Kyrgyzstan, a background site in Central Asia using the long-term (similar to 14 years: August 2007-November 2021) data acquired with the Cimel sunphotometer. The mean aerosol optical depth (AOD) and Angstrom exponent (AE) during the observation period were 0.14 +/- 0.10 and 1.19 +/- 0.41, respectively. Both AOD and AE varied across seasons, with highest AOD in spring (0.17 +/- 0.17). Regarding the aerosol types, clean continental aerosols were dominant type (65%), followed by mixed aerosols (similar to 19%), clean marine aerosols (similar to 14%), dust (0.8%), and urban/industrial and biomass burning aerosol (0.7%). The aerosol volume size distribution was bimodal indicating the influence of both anthropogenic and natural aerosols with clear dominance of coarse mode during the spring season. Mainly dust and mixed aerosols were present during high aerosol episodes while the coarse mode aerosol volume concentration was 7.5 (strong episodes) and similar to 19 (extreme episodes) times higher than the whole period average. Aerosol over this background sites were from local and regional sources with some contribution of long-range transport.