The role of stratospheric ozone for Arctic-midlatitude linkages

We've developed a machine learning algorithm that allows us to represent the ozone layer as an interactive element in the model, and in so doing, to reflect the interactions from the stratosphere and ozone layer. With the new model system we can now realistically reproduce the observed changes in the jet stream.

Erik Romanowsky, first author and AWI atmospheric researcher

According to the team's findings, sea-ice retreat and the accompanying increased activity of atmospheric waves are creating a significant, ozone-amplified warming of the polar stratosphere. Since the low polar temperatures form the jet stream's motor, the rising temperatures in the stratosphere are causing it to falter. In turn, this weakening of the jet stream is now spreading downward from the stratosphere, producing weather extremes.

Abstract summary

• States that Arctic warming was more pronounced than warming in midlatitudes in the last decades making this region a hotspot of climate change
• States that an associated rapid decline of sea-ice extent and a decrease of its thickness has been observed
• Explains that sea-ice retreat allows for an increased transport of heat and momentum from the ocean up to the tropo- and stratosphere by enhanced upward propagation of planetary-scale atmospheric waves
• Explains that in the upper atmosphere, these waves deposit the momentum transported, disturbing the stratospheric polar vortex, which can lead to a breakdown of this circulation with the potential to also significantly impact the troposphere in mid- to late-winter and early spring
• Explains that an accurate representation of stratospheric processes in climate models is necessary to improve the understanding of the impact of retreating sea ice on the atmospheric circulation
• Models the atmospheric response to a prescribed decline in Arctic sea ice
• Shows that including interactive stratospheric ozone chemistry in atmospheric model calculations leads to an improvement in tropo-stratospheric interactions compared to simulations without interactive chemistry
• This suggests that stratospheric ozone chemistry is important for the understanding of sea ice related impacts on atmospheric dynamics