Abstract
Abstract. A thorough analysis of the ozone transport was carried out using the Transformed-Mean Eulerian (TEM) tracer continuity equation and the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40). In this budget analysis, the chemical net production term, which is calculated as the residual of the other terms, displays the correct features of a chemical sink and source term, including location and seasonality, and shows good agreement in magnitude compared to other methods of calculating ozone loss rates. This study provides further insight into the role of the eddy ozone transport and underlines its fundamental role in the recovery of the ozone hole during spring. The trend analysis reveals that the ozone hole intensification over the 1980–2001 period is not solely related to the trend in chemical losses, but more specifically to the balance between the trends in chemical losses and ozone transport. That is because, in the Southern Hemisphere from October to December, the large increase in the chemical destruction of ozone is balanced by an equally large trend in the eddy transport, associated with a small increase in the mean transport. This study shows that the increase in the eddy transport is characterized by more poleward ozone eddy flux by transient waves in the midlatitudes and by stationary waves in the polar region. Overall, this study makes clearer the close interaction between the trends in ozone chemistry and ozone transport. It reveals that the eddy ozone transport and its long-term changes are an important natural mitigation mechanism for the ozone hole. This work also underlines the need for diagnostics of the eddy transport in chemical transport models used to investigate future ozone recovery.
Highlights
In the 1920s, chlorofluorocarbons (CFC) started replacing more toxic compounds like ammonia, chloromethane or sulfur dioxide as refrigerants as well as propellants in aerosol cans, fire extinguishers or cleaning solvents
A thorough analysis of the ozone transport was carried out using the Transformed-Mean Eulerian (TEM) tracer continuity equation with the ERA-40 re-analysis
The chemical term displays the correct features of a chemical sink and source term, including location and seasonality, and shows good agreement in magnitude compared to other methods of calculating ozone loss rates
Summary
In the 1920s, chlorofluorocarbons (CFC) started replacing more toxic compounds like ammonia, chloromethane or sulfur dioxide as refrigerants as well as propellants in aerosol cans, fire extinguishers or cleaning solvents. In 1974, CFCs were identified as the major source of ozone-destroying stratospheric chlorine (Molina and Rowland, 1974), a chemical element that was shown could engage in a catalytic cycle resulting in ozone destruction (Stolarski and Cicerone, 1974). Countless observational studies have reported that the total column ozone has decreased over many regions of the globe since about 1980, with severe ozone depletion over the Antarctica in the spring, leading to what is referred to as the ozone hole. Over Antarctica, extreme low temperatures during winter and early spring facilitate the formation of polar stratospheric clouds (PSCs), which support chemical reactions that produce active chlorine, which goes on to catalyze ozone destruction. Many observational and modeling studies have focused
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