A connection from Siberian snow cover to Arctic stratospheric ozone

The scientific community has been increasingly interested in the climatic effects of Arctic stratospheric ozone (ASO) in recent years. However, ASO exhibits substantial variability, and the underlying factors contributing to it are not fully understood. Here, a diagnostic analysis utilizing data from multiple sources reveals that on interannual time scale, March ASO can be effectively modulated by the snow cover in Siberia during the preceding September and October. The Siberian snow cover can explain approximately 15–21% of the interannual variation in ASO, typically manifesting as a decrease in snow cover corresponding to the increase in ASO. The reduced snow cover benefits a deceleration of the circumpolar westerlies, the sea ice loss in the Barents-Kara Seas, the positive Pacific-North American pattern, and the negative Aleutian-Icelandic Low Seesaw pattern, which amplify the intensity of planetary waves propagating upward into the stratosphere. The enhanced planetary waves are characterized by the stratospheric dipole-like pattern during the preceding October and December and contribute to the continuous weakening of the polar vortex from January to March. In March, the weakened polar vortex inhibits the chemical loss of ASO, while the strengthened Brewer-Dobson circulation significantly promotes the poleward transport of ozone. The combined effect of both processes results in a substantial increase in ASO. Our study uniquely connects the surface cryosphere to the chemical substances in the Arctic stratosphere, anticipating by 6–7 months. This might bring new understandings for future predictions of ASO and its climatic effects. Additionally, it would be interesting to examine whether the March ASO will influence the subsequent spring snow cover over Eurasia.