Abstract
Abstract. A three-dimensional (3-D) chemical transport model (CTM), SLIMCAT, has been used to quantify the effect of denitrification on ozone loss for the Arctic winter 2004/2005. The simulated HNO3 is found to be highly sensitive to the polar stratospheric cloud (PSC) scheme used in the model. Here the standard SLIMCAT full chemistry model, which uses a thermodynamic equilibrium PSC scheme, overpredicts the ozone loss for Arctic winter 2004/2005 due to the overestimation of denitrification and stronger chlorine activation than observed. A model run with a coupled detailed microphysical denitrification scheme, DLAPSE (Denitrification by Lagrangian Particle Sedimentation), is less denitrified than the standard model run and better reproduces the observed HNO3 as measured by Airborne SUbmillimeter Radiometer (ASUR) and Aura Microwave Limb Sounder (MLS) instruments. Overall, denitrification is responsible for a ~30 % enhancement in O3 depletion compared with simulations without denitrification for Arctic winter 2004/2005, which is slightly larger than the inferred impact of denitrification on Arctic ozone loss for previous winters from different CTMs simulations. The overestimated denitrification from standard SLIMCAT simulation causes ~5–10 % more ozone loss at ~17 km compared with the simulation using the DLAPSE PSC scheme for Arctic winter 2004/2005. The calculated partial column ozone loss from SLIMCAT using the DLAPSE scheme is about 130 DU by mid-March 2005, which compares well with the inferred column ozone loss from ozonesondes and satellite data (127±21 DU).
Highlights
Significant progress has been made in understanding the processes controlling the observed polar stratospheric ozone depletion during the recent decades through measurements, laboratory work and modelling studies (e.g., Solomon, 1999; Chipperfield et al, 2005)
We have used a three-dimensional (3-D) chemical transport model SLIMCAT to quantify the effect of denitrification on ozone loss for the Arctic winter 2004/2005
The results showed that the model using the Denitrification by Lagrangian Particle Sedimentation (DLAPSE) microphysical denitrification scheme is able to produce denitrification and in good agreement with observations for the previous Arctic winters (e.g., 1999/2000, 2003/04)
Summary
Significant progress has been made in understanding the processes controlling the observed polar stratospheric ozone depletion during the recent decades through measurements, laboratory work and modelling studies (e.g., Solomon, 1999; Chipperfield et al, 2005). Feng et al (2007a) found that an updated version of the SLIMCAT 3-D chemical transport model (CTM) (Chipperfield, 2006) overestimated the observed ozone loss in the cold Arctic winter of 2004/2005. Further investigations of the processes which lead to Arctic ozone depletion are required to better understand the discrepancies between models and observed ozone loss. We investigate the impact of using different model PSC schemes, including effect of denitrification on the ozone loss for the Arctic winter 2004/2005. We use airborne and satellite remote sensing observations from the Airborne Submillimeter Radiometer (ASUR) and Aura Microwave Limb Sounder (MLS) instruments to test the denitrification simulated by the model for the different PSC schemes
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