Aerosol components and types in the Baltic Sea region

Atmospheric aerosol observed in Estonia in summer 2002 was classified with different methods. The aim of the investigation was to identify and characterise the main aerosol types and components in order to facilitate modelling of the regional aerosol. The classification scheme used enabled to identify aerosol types proceeding from the optical char acteristics of aerosol in the UV region. The optical and size distribution characteristics were specified for the following aerosol types: marine clean mixed with continental clean, marine polluted mixed with continental average, continental polluted, and continental polluted mixed with smoke. Another classification method was based on the decomposition of the measured aerosol size distributions to basic aerosol components. It enabled a flexible linking of aerosol size distribution, composition, and optical properties. Percentages (mean ± SD for 17 days) of the basic components in the aerosol volume was estimated as follows: soot = 1.2% ± 1.4%, insoluble = 23.1% ± 8.3%, water-soluble = 44.0% ± 10.8%, accumulation mode sea salt = 31.6% ± 6.2%.