Atmospheric transport model applied to understand the effect of biogenic emissions to secondary atmospheric aerosol in hemiboreal zone

The SILAM model with built-in isoprene and monoterpene emission module from natural sources was run for May to August 2006 in Baltic Sea region. In this study VOCs were advected as passive tracers. Modelled hourly VOC-tracer concentrations were compared with sub-half-micrometre aerosol concentrations, simultaneously measured in Preila (Lithuania), Tahkuse (Estonia), Hyytiala (southern Finland) and Varrio (northern Finland). Linear correlation coefficients between measured and modelled concentrations were found in range 0.45 to 0.72. Bilinear regression result, based on summary monoterpenes and sulphate (AQME II model run, FMI), is even better correlated with aerosol: coefficients from 0.58 to 0.83. Thus, biogenic VOCs and sulphates are likely two major contributors to the sub-half-micron aerosol in the Nordic-Baltic region. This study demonstrates that a state-of-art advection-diffusion model with proper emission database is capable to predict the accumulation mode aerosol concentrations in the atmosphere...