Ozone Changes damp the CO2-induced Tracer Transport in the Stratosphere.

What is it about?

A robust circulation response to enhanced CO2 is the strengthening of the equator-to-pole circulation in the stratosphere, the so-called Brewer–Dobson circulation (BDC), which affects the ozone layer by tracer transport. This in turn alters stratospheric temperatures and thereby modifies the stratospheric circulation. In the present study, we perform model experiments to quantify the ozone-induced circulation changes caused by quadrupled CO2 concentrations. The results show that ozone changes damp the CO2-induced BDC strengthening due to radiative effects of the redistributed ozone layer by enhanced CO2. These ozone modifications lead to strengthened stratospheric easterlies in summer and decelerated westerlies in winter and spring. Moreover, the ozone changes reduce the CO2-induced delay of the polar vortex break down date in the Southern Hemisphere.

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Photo by Matteo Fusco on Unsplash

Photo by Matteo Fusco on Unsplash

Why is it important?

The findings underline the importance of the role of ozone for the circulation response to increasing CO2 mixing ratios, indicating that ozone-circulation coupling generally damps the atmospheric circulation response. This might have important consequences for understanding intermodel differences in the circulation response, and generally shows that a realistic representation of ozone in climate models is essential not only for its impact on chemistry, but also because it has a considerable effect on atmospheric temperatures and circulations.

Perspectives