The long-term trend in the size of the Antarctic ozone hole has impacted Southern Hemisphere surface climate by shifting the wind patterns further south, away from Australia. As well as these long-term trends, recent observational studies have linked the year-to-year variability of the size of the ozone hole to changes in temperatures over Australia, with unusually hot summer seasons associated with unusually small spring ozone holes and vice versa.
CLEX researchers with collaborators from around the world have performed the first study to investigate whether climate models can capture the influence of the year-to-year ozone hole size on Australian temperatures. The aim was to explore whether this could help seasonal predictions of Australian temperatures.
The researchers examined the year-to-year ozone-temperature connection in multiple observational datasets and compared this with simulations from models participating in the Chemistry-Climate Model Initiative. They found some models do capture the observed connection between the size of the Antarctic ozone hole in November and Australian summer surface temperatures.
One model was examined in more detail to explore this relationship. The researchers found a systematic difference between experiments using realistic observed sea surface temperatures (uncoupled) and those with an interactive ocean (coupled).
Strong correlations between the size of the ozone hole and Australian temperatures were only obtained in the uncoupled experiment. This suggests the sea surface temperatures could be important for driving both variations in Australian temperatures and the ozone hole, with no actual causal link between the two.
The researchers also explored the role of observational uncertainty and model biases in the strength of the ozone-temperature relationship.
The results indicate a potential advantage in improving stratospheric and ozone chemistry representation in climate models and suggest that incorporating Antarctic spring ozone variability could improve seasonal predictions.
- Paper: Gillett, Z. E., J. M. Arblaster, A. J. Dittus, M. Deushi, P. Jöckel, D. E. Kinnison, O. Morgenstern, D. A. Plummer, L. E. Revell, E. Rozanov, R. Schofield, A. Stenke, K. A. Stone, and S. Tilmes, 2019: Evaluating the Relationship between Interannual Variations in the Antarctic Ozone Hole and Southern Hemisphere Surface Climate in Chemistry–Climate Models. J. Climate, 32, 3131–3151, https://doi.org/10.1175/JCLI-D-18-0273.1
- Picture (top): Noctilucent clouds taken from space. Credit NASA.