Atmospheric sulphuric acid and aerosol formation: implications from atmospheric measurements for nucleation and early growth mechanisms

S.-L. Sihto (1) , M. Kulmala (1) , V.-M. Kerminen (2) , M. Dal Maso (1) , T. Petäjä (1) , I. Riipinen (1) , H. Korhonen (2) , F. Arnold (3) , R. Janson (4) , M. Boy (1) , A. Laaksonen (5) , K. E. J. Lehtinen (6)

1 Helsingin yliopisto = Helsingfors universitet = University of Helsinki
2 FMI - Finnish Meteorological Institute
3 MPIK - Max Planck Institute for Nuclear Physics
4 ACES - Department of Environmental Science and Analytical Chemistry [Stockholm]
5 University of Kuopio
6 Department of Applied Physics [Kuopio]

We have investigated the formation and early growth of atmospheric secondary aerosol particles building on atmospheric measurements. The measurements were part of the QUEST 2 campaign which took place in spring 2003 in Hyytiälä (Finland). During the campaign numerous new aerosol particle formation events occurred of which 15 were accompanied by gaseous sulphuric acid measurements. Our detailed analysis of these 15 events is focussed on nucleation and early growth (to a diameter of 3 nm) of fresh particles. It revealed that new particle formation seems to be a function of the gaseous sulphuric acid concentration to the power from one to two. The former would be consistent with the recently developed activation theory while the latter would be consistent with the kinetic nucleation theory. We find that some events are dominated by the activation mechanism and some are dominated by the kinetic mechanism. Inferred coefficients for the two nucleation mechanisms are correlated with the product of gaseous sulphuric acid and ammonia concentrations. This indicates that besides gaseous sulphuric acid also ammonia has a role in nucleation. Early growth of fresh particles to a diameter of 3 nm has a mean rate of 1.2 nm/h and is clearly correlated with the gaseous sulphuric acid concentration.

Domaines: Océan, Atmosphère

S.-L. Sihto, M. Kulmala, V.-M. Kerminen, M. Dal Maso, T. Petäjä, et al.. Atmospheric sulphuric acid and aerosol formation: implications from atmospheric measurements for nucleation and early growth mechanisms. Atmospheric Chemistry and Physics Discussions, 2006, 6 (3), pp.3845-3882. ⟨hal-00301295⟩