Impact of dynamically induced ozone mini-hole events on PSC formation and chemical ozone destruction

Abstract

The impact of ozone mini-holes over the extra-tropics of the northern hemisphere on the heterogeneous ozone chemistry is investigated, based on simulations with the coupled climate-chemistry model ECHAM4.L39(DLR)/CHEM. Ozone mini-holes are synoptic-scale regions of strongly reduced total ozone, directly associated with upper troposphere high pressure systems. The simulated mini-hole events are validated with a mini-hole climatology based on daily ozone measurements with the total ozone mapping spectrometer (TOMS) instrument on the satellite Nimbus-7 between 1979 and 1993. Furthermore, the impact of mini-holes on the stratospheric heterogeneous ozone chemistry is investigated indirectly. For this purpose, polar stratospheric cloud formation inside mini-holes is suppressed during the model simulation. Heterogeneous processes inside mini-holes amount to one third of the heterogeneous ozone destruction in general over northern mid- and high-latitudes during winter (January–April). This ozone perturbation subsides and recovers during summer with an e-folding time of two months.