Global, regional and seasonal analysis of total ozone trends derived from the 1995–2020 GTO-ECV climate data record

• Main Authors: Coldewey-Egbers, Melanie, Loyola, Diego G., Lerot, Christophe, Roozendael, Michel
• Format: Text
• Language: English
• Published: 2022
• Subjects: North Atlantic
• Online Access: https://doi.org/10.5194/acp-2021-1047; https://acp.copernicus.org/preprints/acp-2021-1047/

In this study we present an updated perspective on near-global total ozone trends for the period 1995–2020. We use the GOME-type Total Ozone Essential Climate Variable (GTO-ECV) satellite data record which has been extended and generated as part of the European Space Agency’s Climate Change Initiative (ESA-CCI) and European Union Copernicus Climate Change Service (EU-C3S) ozone projects. The focus of our work is the analysis of regional patterns in the ozone trend as well as the investigation of its seasonal dependence. In the Southern Hemisphere we found regions that indicate statistically significant positive trends increasing from 0.6 ± 0.5 % decade −1 in the subtropics to 1.0 ± 0.9 % decade −1 in the middle latitudes and 2.8 ± 2.6 % decade −1 in the latitude band 60°–70° S. In the middle latitudes of the Northern Hemisphere the trend exhibits distinct regional patterns, i.e. latitudinal and longitudinal structures. Significant positive trends (∼1.5 ± 1.0 % decade −1 ) over the North Atlantic region as well as negative trends (−1.0 ± 1.0 % decade −1 ) over Eastern Europe were found. Moreover, these trends indicate a correlation with long-term changes in tropopause pressure. Total ozone trends in the tropics are not significant. Regarding the seasonal dependence of the trends we found only very small variations over the course of the year. However, we identified different behavior depending on latitude. In the latitude band 40°–70° N the positive trend maximizes in boreal winter from December to February. In the middle latitudes of the Southern Hemisphere (35°–50° S) the trend is maximum from March to May. Further south toward the high latitudes (55°–70° S) the trend denotes a relatively strong seasonal cycle which varies from 2 % decade −1 in December and January to 3.8 % decade −1 in June and July.