Observations of Particle Nucleation and Growth Events in the Lower Free Troposphere
Atmospheric nucleation events were regularly observed during the fourth Cloud and Aerosol Characterization Experiment (CLACE 4), conducted at the high alpine research station Jungfraujoch in winter 2005. Nucleation was observed to occur both during the absence and presence of clouds, and was sometimes accompanied by an overcharging of the small particles. We analysed the measured size distributions with the PARGAN procedure to determine empirical particle growth and nucleation rates, taking into account the effect of coagulation. Though nucleation rates were found to be small (<1 cm−3 s−1), the regular occurrence of nucleation events suggests that they could contribute significantly to the tropospheric aerosol number budget.
Keywords Nucleation rate, growth rate, free tropospheric aerosol, aerosol dynamics
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