HR: 10:40h
AN: A52B-02 INVITED     [Abstracts]
TI: Assessing the Response of Aerosol Nucleation, Cloud Parameters, and Radiative Forcing Over Oceans to Variations in Galactic Cosmic Ray Intensity
AU: * Kazil, J
EM: jan.kazil@noaa.gov
AF: Aeronomy Laboratory, National Atmospheric and Oceanic Administration, 325 Broadway, Boulder, CO 80305-3328 United States
AU: * Kazil, J
EM: jan.kazil@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, 216 UCB, Boulder, CO 80309-0216 United States
AU: Lovejoy, E R
EM: edward.r.lovejoy@noaa.gov
AF: Aeronomy Laboratory, National Atmospheric and Oceanic Administration, 325 Broadway, Boulder, CO 80305-3328 United States
AU: Barth, M C
EM: barthm@ucar.edu
AF: Mesoscale and Microscale Meteorology Division / Atmospheric Chemistry Division, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 United States
AU: O'Brien, K
EM: keran.o'brien@nau.edu
AF: Department of Physics and Astronomy, Northern Arizona University, NAU Box 6010, Flagstaff, AZ 86011-6010 United States
AB: Atmospheric ions are likely aerosol precursors because they greatly stabilize small clusters with respect to evaporation. A source of atmospheric ions are galactic cosmic rays (GCR). The variation of GCR intensity over the decadal solar cycle might thus appear in aerosol and cloud condensation nuclei concentrations. The resulting variation of cloud droplet size distributions and concentrations, and hence of cloud albedo and cloud lifetime would bear upon radiative forcing of the troposphere. We analyze the response of aerosol production over the oceans to the variation of GCR intensity over the decadal solar cycle using results from a model of neutral and charged H₂O/H₂SO_4 aerosol microphysics. Our model employs laboratory thermodynamics for the growth and evaporation of charged, and modified liquid drop thermodynamics for the growth and evaporation of neutral H₂O/H₂SO_4 clusters, respectively. Input data are taken from a model of galactic cosmic rays in the atmosphere, and from global chemistry and transport models. We give an upper limit to the possible response of cloud albedo and cloud amount to variations in GCR intensity in the course of the decadal solar cycle via the first and second indirect aerosol effects, and to the consequential response of tropospheric radiative forcing. Uncertainties arising from our approach are discussed.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0335 Ion chemistry of the atmosphere (2419, 2427)
DE: 1650 Solar variability (7537)
DE: 2104 Cosmic rays
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005