Liquid particle composition and heterogeneous reactions in a mountain wave Polar Stratospheric Cloud

D. Lowe (1) , A. R. Mackenzie (1) , H. Schlager (2) , C. Voigt (2) , A. Dörnbrack (2) , M. J. Mahoney (3) , F. Cairo (4)

1 Environmental Science Dept.
2 IPA - Institute for Atmospheric Physics [Mainz]
3 JPL - Jet Propulsion Laboratory
4 ISAC - CNR Institute of Atmospheric Sciences and Climate

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. The observations of PSC particle composition, backscatter and chlorine activation are studied with a recently developed dynamical microphysical non-equilibrium box model. Results from the microphysical model, run on quasi-lagrangian trajectories, show that the PSC is composed of supercooled ternary (H₂O/HNO₃/H₂SO₄) solutions (STS) particles, which are out of equilibrium with the gas phase. The optical properties 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 in reasonable agreement with the measured ClO_x concentrations, but high solar zenith angles prevent a direct comparison. Equilibrium calculations commonly used in large scale chemistry transport models poorly represent the measured PSC particle composition and chlorine activation under mountain wave conditions.

Domaines: Océan, Atmosphère

D. Lowe, A. R. Mackenzie, H. Schlager, C. Voigt, A. Dörnbrack, et al.. Liquid particle composition and heterogeneous reactions in a mountain wave Polar Stratospheric Cloud. Atmospheric Chemistry and Physics Discussions, 2005, 5 (5), pp.9547-9580. ⟨hal-00301827⟩