In this study the aerosols influence on selected meteorological parameters during two summer 2010 periods is evaluated with focus on the North-West Russia and urban area of St. Petersburg. For that, the seamless fully online-integrated Enviro-HIRLAM model is used. The simulations are realised in short- and long-term modes for selected periods. For evaluation of aerosol influence, in addition to the control/ reference run, the runs with direct, indirect and both combined aerosol effects are performed.

It was found that for the North-West Russia region, the direct aerosol effect had increased air temperature (by 1-3˚) and decreased total cloud cover (by 10-20%). The indirect effect decreased temperature (by 0.4-1˚) and increased cloud cover (by 10-20%). The combined effect was the largest territorially; and such effect both decreased temperature and cloud cover (by 1-3˚ and by 6-20%, respectively) as well as increased these (by 0.4-0.6˚ and 1020%).