HR: 11:19h
AN: A22D-04    [Abstracts]
TI: Efficiency of primary and secondary aerosols in indirect aerosol effects
AU: * Stier, P
EM: philip.stier@gmail.com
AF: University of Oxford Philip Stier, Atmospheric, Oceanic and Planetary Physics Clarendon Laboratory Parks Road, Oxford, U.K OX1 3PU, United Kingdom
AU: Seinfeld, J H
EM: seinfeld@caltech.edu
AF: California Institute of Technology John H. Seinfeld, 1200 E. California Blvd. M/C 210-41, Pasadena, CA 91125, United States
AU: Lohmann, U
EM: ulrike.lohmann@env.ethz.ch
AF: ETH-Zentrum Ulrike Lohmann, Institut f. Atmosphäre und Klima CHN O 11 Universitätstrasse 16, Zürich, 8092, Switzerland
AU: Quaas, J
EM: johannes.quaas@zmaw.de
AF: Max Planck Institute for Meteorology Johannes Quaas, Bundesstraße 53, Hamburg, D-20146, Germany
AB: Atmospheric aerosols play an important role in the global climate system through modifications of the global radiation budget: directly, by scattering and absorption of radiation and indirectly, by the modification of cloud properties and abundance. In particular the indirect aerosol effects on clouds are subject to large uncertainties. Global aerosol-cloud climate models allow quantitative estimates, albeit uncertain, of anthropogenic indirect aerosol effects. In this study we investigate the indirect aerosol effects through modeling studies with the ECHAM5-HAM aerosol- climate model with microphysical representation of aerosol-cloud interactions: we utilize its prognostic aerosol size-distribution, mixing state and cloud droplet number concentration to explicitly couple the aerosol and cloud systems via an explicit, Koehler theory based, aerosol activation scheme. Our focus is on the different efficiencies of primary and secondary aerosols in perturbing the global radiation balance - as our previous work has indicated non-negligible differences in the ability to form accumulation mode sized particles, as surrogate for cloud condensation nuclei. We present the modeling results in synergy with satellite observations of aerosol and cloud parameters, providing strong observational constraints on the simulated global aerosol-cloud interactions. Our results help reduce uncertainties in estimates of the indirect aerosol effects and provide valuable information for the necessary level of detail in the microphysical process representation in global models of aerosol-cloud interactions.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0321 Cloud/radiation interaction
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting