Variations of trace gases, meteorological parameters, and their connection with aerosol formation in boreal forests

[1] The data of observations at Hyytiala background station in 1997 – 2003 are analyzed for investigating the possible links between physical, chemical, and meteorological parameters for event and nonevent days for different seasons. The seasonal patterns of average trace gases concentrations (O3, H2O, NOx= NO + NO2, SO2), UV-A irradiation, temperature, relative humidity, condensational sinks are established and used for evaluating their influence on the seasonal dependence of formation and growth rates of particles in the nucleation mode. The condensational sinks are shown to play a crucial role in the chemical dynamics of the gaseous precursors and the aerosol particles. The variations of the sinks are mainly attributed to the humidification of the preexisting aerosol and thus strongly depend on the relative humidity.