[A-AS09] Stratosphere-troposphere Processes And their Role in Climate

[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)

Keywords: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.