Signatures of the North Atlantic Oscillation on stratospheric ozone

One of the primary mode of wintertime extratropical variability, the North Atlantic Oscillation (NAO) has recently been argued to be part of a more global pattern, termed the Arctic Oscillation (AO), which extends from the surface upwards into the stratosphere. The AO point-of-view has hence highlighted the coupling of the NAO with the stratosphere and the ozone layer.

In this study, we examine the signature of the NAO/AO on the ozone layer. Analysis of satellite column ozone observations indicate a strong signature of storm tracks in ozone, with marked asymmetries between the Pacific and Atlantic storm tracks. The storm track modulation by the NAO/AO over the Atlantic hence strongly influences ozone transient variability over the Atlantic and Europe.

Nearly 20 years of TOMS observations are used to diagnose whether the patterns of wintertime ozone synoptic variability depend on the NAO/AO. Of particular interest are the large amplitude ozone "mini-hole" events that frequently develop over the Atlantic in winter. We examine the relationship between the occurrences of such ozone minihole events and the NAO.