Ozone depletion leads to warming of the upper stratosphere in Antarctica in winter

Schematic representation of temperature changes in the upper stratosphere of Antarctica during the southern winter. Note that BD stands for “Brewer-Dobsonian” circulation, which refers to the pattern of tropical tropospheric air that rises into the stratosphere and then moves poleward as it descends. Photo credit: Xuan Ma

Since the discovery of the Antarctic ozone hole in the 1980s, numerous studies have indicated that this ozone depletion in Antarctica has important implications for global climate change, and that the changes in Antarctic stratospheric temperatures during the southern winter are of major importance for ozone depletion and formation of the ozone hole.

Previous studies have shown that temperatures in Antarctica’s upper stratosphere have not cooled, in contrast to cooling in the lower stratosphere; Rather, there has been significant warming in this part of the stratosphere since the 1970s. This is in contrast to the radiative effects of ozone depletion and increased greenhouse gas concentrations.

Recently Dr. Xuan Ma and Dr. Lei Wang of the Department of Atmospheric and Oceanic Sciences at Fudan University in China points out that the temperature of the upper stratosphere in Antarctica has shown significant warming in southern winters since the 1970s. These results are published in the journal Advances in atmospheric science and stress the need to pay more attention to the dynamic processes in the stratosphere related to ozone depletion.

To isolate the role of ozone depletion and rising greenhouse gas concentrations, the authors used simulations from state-of-the-art chemistry-climate models run under different future forcing scenarios. It was found that changes in the dynamic processes associated with the observed ozone depletion were largely responsible for the warming of the upper stratosphere in Antarctica.

In particular, radiative cooling caused by ozone depletion led to a stronger meridional temperature gradient between the middle and high latitudes in the upper stratosphere. This allowed more planetary waves (waves in the atmosphere caused by the Earth’s rotation) to propagate upward, eventually warming Antarctica’s upper stratosphere. These results could help improve our understanding of the coupling between atmospheric chemistry and climate in the southern upper stratosphere.

To verify the model results, the authors also performed some calculations at southern high latitudes using multiple reanalysis datasets (combinations of observations and model outputs used to generate estimates of the state of the studied system). However, the quality of reanalysis data in the upper Antarctic stratosphere needs to be further improved, which will require more detailed observations in this part of the atmosphere in the future.

More information:
Xuan Ma et al, The Role of Ozone Depletion in the Lack of Cooling in the Antarctic Upper Stratosphere during Austral Winter, Advances in atmospheric science (2023). DOI: 10.1007/s00376-022-2047-9

Provided by the Chinese Academy of Sciences

Citation: Ozone depletion leads to warming of the upper stratosphere in Antarctica in winter (2023, February 16), retrieved February 16, 2023 from https://phys.org/news/2023-02-ozone-depletion-antarctic-upper -stratospheric-winter.html

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