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

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 HNO 3 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 HNO 3 as measured by Airborne SUbmillimeter Radiometer (ASUR) and Aura Microwave Limb Sounder (MLS) instruments. Overall, denitrification is responsible for a ∼30 % enhancement in O 3 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).

Inclusion of mountain-wave-induced cooling for the formation of PSCs over the Antarctic Peninsula in a chemistry–climate model

“…resulting in synoptic-scale temperatures which fall below the PSC temperature threshold when in reality they should be above it, which as a consequence cause the formation of too many PSCs and associated increased ozone losses (Austin and Butchard, 2003). Moreover, the equilibrium PSC scheme used by the UKCA module does not advect PSC particles (Feng et al, 2011). This means that the occurrence of circumpolar belts of PSCs which have been attributed to mountain-wave-induced PSCs over regions such as the AP would not be represented.…”

“…We simulate this effect by using the cooling phase only. In future work we plan to insert the microphysical scheme DLAPSE (Denitrification by Lagrangian Particle Sedimentation) (Feng et al, 2011) into the UKCA module, and couple it to both the cooling and warming phases of the parameterised temperature fluctuations.…”

“…The equilibrium PSC scheme provides a realistic representation of the existence of PSC particles when air temperatures drop below the PSC temperature formation threshold (e.g. Feng et al, 2011). However, the scheme does not represent a slow decline of PSC existence when temperatures rise abruptly above the temperature threshold.…”

Antarctic ozone hole as observed by IASI/MetOp for 2008–2010

“…It is thought that inside the polar vortex approximately 60 % of the ozone destruction is caused by the release of active chlorine and the remainder by the release of bromine, hydrogen and nitrogen (Feng et al, 2005(Feng et al, , 2011. During polar night a polar vortex forms over Antarctic, holding the air mass within.…”

A Match-based approach to the estimation of polar stratospheric ozone loss using Aura Microwave Limb Sounder observations

“…This method was first developed by Manney et al (1995b, a) to quantify ozone loss during the 1992/93 Arctic winter, using a trajectory-based passive ozone estimate, and has been subsequently applied in similar form to other seasons (e.g., Manney et al, 1996aManney et al, , b, 1997Manney et al, , 2003Schoeberl et al, 2002). Where a full chemistry transport model is employed (e.g., Deniel et al, 1998;Goutail et al, 1999;Singleton et al, , 2007; L. Grooß and Müller, 2007;Rösevall et al, 2008;Jackson and Orsolini, 2008;Kuttippurath et al, , 2012Feng et al, 2011;Brakebusch et al, 2013), ozone loss can be estimated by comparing the modeled passive ozone to both the ozone simulated by the same model and to observed ozone, with comparisons between the latter two fields typically used to quantify the overall accuracy of the model calculations (both from the dynamical and chemical perspective). The passive subtraction approach can be taken a stage further by considering a "pseudo passive" ozone tracer , subject to both dynamical and gas-phase chemistry influences, but not the losses due to chlorine activated through heterogeneous processes.…”