Heidelberg 2015 – scientific programme

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UP: Fachverband Umweltphysik

UP 2: Atmosphäre

UP 2.1: Invited Talk

Wednesday, March 25, 2015, 09:00–09:30, G/gHS

Ozone trends and variability in a changing climate — •Mark Weber — Universität Bremen FB1, Bremen,Germany

Three decades of global satellite observations of ozone show variability on various time scales related to atmospheric dynamics as well as to stratospheric halogen changes following the phasing out of ozone depleting substances (ODS) in response to the Montreal Protocol and its Amendments. Many climate models predict a strengthening in the Brewer-Dobson circulation in a changing climate, which is expected to increase ozone transport into high latitudes, thus accelerating the ongoing ozone recovery as a result from decreasing halogen levels. However, observed total ozone trends (representative of lower stratosphere ozone) do not show statistically significant positive trends since 2000. Nevertheless, the trend change from the long-term decrease observed before is robust, thus confirming the success of the Montreal protocol.

From limb satellite observations during the last decade positive ozone trends in the upper stratosphere are observed and are indicative of ODS related ozone recovery. From climate model studies it appears that both changes in greenhouse gases and ODS have about equal contribution to the observed ozone changes in this altitude region. In contrast a continuous negative ozone trend is observed between 30 and 40 km altitude (middle stratosphere) in the tropics. In the lowermost tropical stratosphere ozone has leveled off, which, however, is related to changes in the tropical upwelling. Highlights from the current WMO ozone assessment released in January 2015 will be presented.