Liquid particle composition and heterogeneous reactions in a mountain wave Polar Stratospheric Cloud D. Lowe1, A. R. MacKenzie1, H. Schlager2, C. Voigt2, A. Dörnbrack2, M. J. Mahoney3, and F. Cairo4 1Environmental Science Dept., Lancaster University, Lancaster, UK 2Institute for Atmospheric Physics, DLR, Oberpfaffenhofen, Germany 3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA 4Institute of Atmospheric Sciences and Climate of the National Research Council (CNR-ISAC), Rome, Italy
Abstract. Mountain wave polar stratospheric clouds (PSCs) were detected on 8 February
2003 above the Scandinavian Mountains by in-situ instruments onboard the M55
Geophysica aircraft. PSC particle composition,
backscatter and chlorine activation for this case are studied with a recently developed
non-equilibrium microphysical box model for liquid aerosol. Results from the
microphysical model, run on quasi-lagrangian trajectories, show that the PSC
observed was composed of supercooled ternary (H2O/HNO3/H2SO4)
solution (STS) particles, which are out of equilibrium with the gas phase.
The measured condensed nitric acid and aerosol backscatter of the PSC can well be simulated with the model. Up to
0.15 ppbv Cl2 can be released by the PSC within 2 h, showing the propensity
of these small-scale clouds for chlorine activation. Equilibrium calculations
– of the sort commonly used in large scale chemistry transport models –
overestimate the measured condensed nitrate by up to a factor of 3, and overestimates chlorine activation
by 10%, in this mountain wave cloud.
Citation: Lowe, D., MacKenzie, A. R., Schlager, H., Voigt, C., Dörnbrack, A., Mahoney, M. J., and Cairo, F.: Liquid particle composition and heterogeneous reactions in a mountain wave Polar Stratospheric Cloud, Atmos. Chem. Phys., 6, 3611-3623, doi:10.5194/acp-6-3611-2006, 2006.