Modelling the effect of denitrification on polar ozone depletion for Arctic winter 2004/2005

摘要

A three-dimensional (3-D) chemical transport model (CTM), SLIMCAT, has beenused to quantify the effect of denitrification on ozone loss for the Arcticwinter 2004/2005. The simulated HNO₃ is found to be highly sensitive tothe polar stratospheric cloud (PSC) scheme used in the model. Here thestandard SLIMCAT full chemistry model, which uses a thermodynamic equilibriumPSC scheme, overpredicts the ozone loss for Arctic winter 2004/2005 due tothe overestimation of denitrification and stronger chlorine activation thanobserved. A model run with a coupled detailed microphysical denitrificationscheme, DLAPSE (Denitrification by Lagrangian Particle Sedimentation), isless denitrified than the standard model run and better reproduces theobserved HNO₃ as measured by Airborne SUbmillimeter Radiometer (ASUR) andAura Microwave Limb Sounder (MLS) instruments. Overall, denitrification isresponsible for a ~30 % enhancement in O₃ depletion comparedwith simulations without denitrification for Arctic winter 2004/2005, whichis slightly larger than the inferred impact of denitrification on Arcticozone loss for previous winters from different CTMs simulations. Theoverestimated denitrification from standard SLIMCAT simulation causes~5–10 % more ozone loss at ~17 km compared with thesimulation using the DLAPSE PSC scheme for Arctic winter 2004/2005. Thecalculated partial column ozone loss from SLIMCAT using the DLAPSE scheme isabout 130 DU by mid-March 2005, which compares well with the inferred columnozone loss from ozonesondes and satellite data (127±21 DU).