HR: 15:25h
AN: A43E-08    [Abstracts]
TI: On the contribution of H₂SO₄-H₂O binary homogeneous and ion-mediated nucleation to new particle formation in the global troposphere
AU: * Yu, F
EM: yfq@asrc.cestm.albany.edu
AF: ASRC, State University of New York at Albany, 251 Fuller Road, Albany, NY 12203, United States
AU: Wang, Z
EM: zifawang@mail.iap.ac.cn
AF: NZC/LAPC, Institute of Atmospheric Physics, Beijing, 100029, China
AU: Luo, G
EM: ganluo@asrc.cestm.albany.edu
AF: ASRC, State University of New York at Albany, 251 Fuller Road, Albany, NY 12203, United States
AU: Luo, G
EM: ganluo@asrc.cestm.albany.edu
AF: NZC/LAPC, Institute of Atmospheric Physics, Beijing, 100029, China
AU: Turco, R
EM: turco@ucla.edu
AF: Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095, United States
AB: New particle formation frequently observed throughout the troposphere is an important source of atmospheric cloud condensation nuclei and is one of key processes that need to be accurately represented in future generations of climate models. The number of parameters controlling the nucleation rates and the dependence of nucleation rates on these parameters based on different nucleation mechanisms vary significantly. Therefore, it is important to identify the right nucleation mechanisms so that the aerosol radiative forcing can be confidently projected based on the future emission scenarios and climate change. We have generated nucleation rate look- up tables for both H₂SO₄-H₂O binary homogeneous nucleation (BHN) and ion-mediated nucleation (IMN) based on the updated kinetic nucleation models which incorporate new thermodynamic data and physical algorithm (Yu, Atmos. Chem. Phys., 6, 5193-5211, 2006; Yu, J. Chem. Phys., 127, 054301, 2007). The BHN and IMN look-up tables have been integrated into a global chemical transport model (GEOS-Chem) to study BHN and IMN contribution to new particle formation in the global troposphere. Based on the kinetic BHN model which is constrained by multiple independent laboratory measurements, BHN is negligible except in the tropical upper troposphere (above around 200 hPa) and a few hot spots in middle and lower troposphere. In contrast, we find that IMN, which appears to be supported by recent measurements of the overcharging of newly formed particles in the boundary layer, can lead to significant new particle formation not only in the upper troposphere but also in the lower troposphere. We have further compared the simulated annual mean results to a comprehensive set of data relevant to new particle formation around the globe. We show that predicted annual spatial patterns of IMN rates agree reasonably well with land-, ship-, and aircraft-based observations. The implications of our simulations and future research needs will be discussed.
UR: http://www.albany.edy/~yfq
DE: 0305 Aerosols and particles (0345, 4801, 4906)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting