HR: 0800h
AN: A31A-0808    [Abstracts]
TI: Evidences for New Particle Formation in the Arctic as a Part of TOPSE Atmospheric Nucleation Event
AU: * Tripathi, S N
EM: snt@iitk.ac.in
AF: Department of Civil Engineering Indian Institute of Technology, IIT Kanpur, Kanpur, UP 208016 India
AU: Kanawade, V P
EM: vijaypk@iitk.ac.in
AF: Department of Civil Engineering Indian Institute of Technology, IIT Kanpur, Kanpur, UP 208016 India
AB: Simultaneous measurements of ultrafine particles and precursor gases show evidences of new particle formation over a wide range of latitude in the free tropospheric Arctic region. However, the exact mechanism of new particle formation is uncertain. In this study, in-situ measurements taken during deployment 3 (Flight 16, March 7, 2000, Churchill-Churchill, 13:25-18:33 GMT) as a part of Tropospheric Ozone Production about Spring Equinox (TOPSE) experiment, over Western Canada were used for comparison with the model predictions. Using a combination of satellite derived brightness temperature, air parcel backward trajectory information, in-situ measurements of aerosol and precursor gases and aerosol microphysical model [Tripathi et al., 2004] driven by parameterized ion induced nucleation [Modgil et al., 2005], we have investigated the plausible mechanism responsible for, and factors leading to, new particle formation in the middle to upper troposphere during TOPSE atmospheric nucleation event. The reasonable agreement between model predicted and observed ultrafine particles of diameter 3 to 4 nm and 3 to 8 nm suggest that new particle formation is likely to occur by ion induced nucleation mechanism during TOPSE nucleation event. A significant finding is that the lowering of pre-existing particle surface, in the region of cloud outflow, triggered particle nucleation in this region. These studies indicate that, at typical middle to upper tropospheric conditions of Arctic, ion mechanism is an important source of ultrafine particles and these freshly particles can grow to act as cloud condensation nuclei (CCN), which have implications for cloud radiative properties. References Modgil, M. S., Sanjeev Kumar, S. N. Tripathi, and E. R. Lovejoy, A parameterization of ion-induced nucleation of sulfuric acid and water for atmospheric conditions, J. Geophys. Res., In press, 2005. Tripathi, S. N., X. P. Vancassel, R. G. Grainger, and H. L. Rogers, A Fast Stratospheric Aerosol Microphysical Model (SAMM): H2SO4-H2O Aerosol Development and Validation, AOPP Memorandum 2004.1, Department of Physics, University of Oxford, 2004. http://www.atm.ox.ac.uk/main/research/technical.html
UR: http://home.iitk..ac.in/~snt
DE: 0305 Aerosols and particles (0345, 4801, 4906)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005