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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, D22307, doi:10.1029/2005JD006886, 2006

On the turnaround of stratospheric ozone trends deduced from the reevaluated Umkehr record of Arosa, Switzerland

P. Zanis

Research Centre for Atmospheric Physics and Climatology, Academy of Athens, Athens, Greece


E. Maillard

Aerological Station Payerne, MeteoSwiss, Payerne, Switzerland


J. Staehelin

Institute for Atmospheric and Climate Science, Eidgenossische Technische Hochschule Zurich, Zurich, Switzerland


C. Zerefos

Laboratory of Climatology and Atmospheric Environment, National and Kapodistrian University of Athens, Athens, Greece
National Observatory of Athens, Athens, Greece


E. Kosmidis

Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece


K. Tourpali

Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece


I. Wohltmann

Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany


Abstract

In this work, we investigate the issue of the turnaround in ozone trends of the recently homogenized Umkehr ozone record of Arosa, Switzerland, which is the longest Umkehr data set, extending from 1956 to date, using different statistical methods. All methods show statistically significant negative ozone trends from 1970 to 1995 in the upper stratosphere (above 32.6 km) throughout the course of the year as well as in the lower stratosphere (below 23.5 km) mainly during winter to spring, which can be partially attributed to dynamical changes. Over the recent period (1996–2004) the year-round trends in the lower stratosphere become positive and are more positive during the winter to spring period. The results also show changes in upper stratospheric ozone trends after 1996, which are, however, not statistically significant at 95% if aerosol correction is applied on the retrieved data. This lack of significant trend changes during the recent period in the upper stratosphere is regionally coherent with recent results derived from upper stratospheric ozone data recorded by lidars, microwave radiometers, and satellite instruments at an adjacent location. Although the positive change in trends after 1996 both for upper and lower stratospheric ozone is in line with the reduction of the emissions of ozone-depleting substances from the successful implementation of the Montreal Protocol and its amendments, we recommend, because of lack of significance for the upper stratospheric trends, repeating this analysis in a few years in order to overcome ambiguous results for documentation of the turnaround of upper stratospheric ozone.

Received 14 November 2005; accepted 17 July 2006; published 23 November 2006.

Keywords: stratospheric ozone trends; Umkehr; turnaround.

Index Terms: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions (0426, 1610); 0325 Atmospheric Composition and Structure: Evolution of the atmosphere (1610, 8125); 0340 Atmospheric Composition and Structure: Middle atmosphere: composition and chemistry; 0399 Atmospheric Composition and Structure: General or miscellaneous; 1610 Global Change: Atmosphere (0315, 0325).

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Citation: Zanis, P., E. Maillard, J. Staehelin, C. Zerefos, E. Kosmidis, K. Tourpali, and I. Wohltmann (2006), On the turnaround of stratospheric ozone trends deduced from the reevaluated Umkehr record of Arosa, Switzerland, J. Geophys. Res., 111, D22307, doi:10.1029/2005JD006886.