Robust Asymmetry of the Future Arctic Polar Vortex Is Driven by Tropical Pacific Warming

• Published in: Geophysical Research Letters
• Main Authors: Matsumura, Shinji, Yamazaki, Koji, Horinouchi, Takeshi
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union
• Subjects: stratospheric polar vortex; climate change; North American stratospheric warming; Tropical Pacific warming; 451; Arctic; Pacific; aleutian low; Climate change
• Online Access: http://hdl.handle.net/2115/83557; https://doi.org/10.1029/2021GL093440

The future stratosphere is globally dominated by a strong radiative cooling due to the increase in greenhouse gases. However, we find that over North America, the Arctic stratospheric cooling is suppressed or rather warming occurs, whereas over Eurasia stratospheric cooling is most pronounced, leading to an asymmetric polar vortex, based on 21st century climate model simulations. There are many causes that drive polar vortex variability, which make future projections highly uncertain. Our model simulations demonstrate that tropical warming induces the asymmetric polar vortex. The eastern equatorial Pacific warming causes eastward-shifted teleconnection with a deepened Aleutian low, which strengthens the polar vortex over Eurasia and weakens over North America by enhancing the vertical wave propagation into the stratosphere. The asymmetric polar vortex is projected to markedly develop in the 2030s, and so could affect winter surface climate over mid- to high-latitudes of Eurasia in the near future.