HR: 1340h
AN: A43C-0113    [Abstracts]
TI: New Ion-Nucleation Mechanism Relevant for the Earth's Atmosphere: Interpreting the Physics.
AU: * Marsh, N D
EM: ndm@spacecenter.dk
AF: Center for Sun-Climate Research, Danish National Space Center Juliane Maries Vej 30, Copenhagen, DK-2100 Denmark
AU: Svensmark, H
EM: hsv@spacecenter.dk
AF: Center for Sun-Climate Research, Danish National Space Center Juliane Maries Vej 30, Copenhagen, DK-2100 Denmark
AU: Pedersen, J P
EM: jopp@spacecenter.dk
AF: Center for Sun-Climate Research, Danish National Space Center Juliane Maries Vej 30, Copenhagen, DK-2100 Denmark
AU: Enghoff, M B
EM: enghoff@spacecenter.dk
AF: Center for Sun-Climate Research, Danish National Space Center Juliane Maries Vej 30, Copenhagen, DK-2100 Denmark
AU: Uggerhøj, U I
EM: ulrik@phys.au.dk
AF: Center for Sun-Climate Research, Danish National Space Center Juliane Maries Vej 30, Copenhagen, DK-2100 Denmark
AB: Experimental studies of ultra-fine aerosol nucleation in clean atmospheric air, containing trace amounts of ozone, sulphur dioxide, and water vapour suggest that the production rate of critical clusters is sensitive to ionisation. To assess this sensitivity numerical simulations of the initial stages of particle coagulation and condensation have been performed and compared with the experimental results. The simulations indicate that a stable distribution of sub 3nm particles exists that cannot be detected using standard techniques for measuring atmospheric aerosol, and that the nucleation rate of critical clusters generating this distribution is a function of the number of ions present. This provides a set of boundary conditions, which constrain the properties of a possible microphysical mechanism. The role of ions in the nucleation process of critical clusters provides a source for new aerosol particles with the potential to influence the transparency of Earth's atmosphere. This is consistent with a number of recent studies indicating that variations in the density of cosmic rays arriving at Earth have affected climate over a wide range of time scales.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0335 Ion chemistry of the atmosphere (2419, 2427)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005