Enhancement of Arctic surface ozone during the 2020–2021 winter associated with the sudden stratospheric warming


 Surface ozone is an important pollutant causing damage to human health and ecosystems. Here we find that the Arctic surface ozone during the 2020–2021 winter is evidently enhanced after the sudden stratospheric warming (SSW) onset based on reanalysis data and simulations of one state-of-the-art chemistry–climate model. Further analysis suggests that this enhancement of Arctic surface ozone is primarily resulted from the strengthening of the stratosphere-to-troposphere transport associated with the SSW. It is found that the SSW leads to more ozone in the Arctic stratosphere and enhanced downward transport with SSW-related downdraft. The 2021 SSW may also lead to positive anomalies in surface ozone in the northern midlatitudes, which are associated with the cold air outbreaks. Our results indicate that the SSW not only affects the weather and climate in the troposphere, but also may affect the surface air quality.