Total ozone and the middle stratosphere over arctic and sub‐arctic areas in winter and spring

Abstract

AbstractIt is well known that the arctic stratosphere customarily exhibits a rapid transition from winter to summer which has a permanent warming effect on stratospheric temperatures and causes a marked decrease in the intensity of the circulation at mid‐stratospheric levels. Prior to this final warming, temporary warmings occur with a marked effect only in sub‐arctic areas. These phenomena are closely related to the rapid increase in total ozone which takes place in the late winter and early spring in polar regions. The major ozone maximum occurs at the time of the final warming, with a magnitude dependent on the intensity of the rapid warming at high levels in the stratosphere. Earlier baroclinic waves during the winter cause closely correlated ozone changes, resulting in a stepwise increase in ozone prior to the final warming.10‐day running means of total ozone and of 100 mb temperature are compared for stations in northern Europe and in Canada; these reveal the relations between long‐period changes and processes in total ozone and in the middle stratosphere. In particular, one may thereby explain the seasonal behaviour of total ozone, which departs so markedly from photochemical prediction, as well as the vital dynamical role played by active centres in the stratospheric warm belt (especially in the Aleutian area) in the production of warm ozone‐rich stratospheric air masses.