[A-AS09] 成層圏・対流圏過程とその気候への影響

[AAS09-P08] Climate Impacts of Solar Cycle and Quasi-Biennial Oscillation: From the Polar Area to Mid-latitude

*King-Fai Li¹、Shuhui Wang²、Lin Tan¹、Andrew Bai³、Annie Bai³、Ka-Kit Tung⁴ (1.University of California, Riverside, California, USA、2.University of California, Los Angeles, California, USA、3.St Paul Academy and Summit School, St Paul, Minnesota, United States、4.University of Washington, Seattle, Washington, USA)

キーワード：Extratropical-tropical teleconnection, Planetary waves, Major warmings

Extratropical stratospheric interannual variability is compounded by the nonlinear effects of the Solar Cycle and the Quasi-Biennial Oscillation (QBO). Compared to the quiescent state (when the tropical stratospheric zonal wind is westerly during the westerly QBO phase and the 11-year Solar Cycle is at the minimum), the winter polar vortex is less stable, and hence may break and cause a major warming event in the late winter (Feb-Mar), when either the QBO is in the easterly phase or the Solar Cycle is at the maximum due to the enhanced convergence of planetary waves in the extratropics. Meanwhile, a planetary-scale cold anomaly in the stratosphere over North America is observed, indicating an exchange of airmass between the polar region and mid-latitudes during the major warming event. This cold anomaly extends downward to the surface in the southern US, leading to a temperature decrease of 0.5-1 K relative to the quiescent state.