Influence of the stratosphere on surface air temperature in China during boreal winter

This study investigates the influence of the Northern Hemisphere stratosphere on winter surface air temperature (SAT) in China, based on the JRA-55 reanalysis dataset and simulations using CAM6. The SAT patterns associated with the stratospheric zonal wind are identified through singular value decomposition (SVD) analysis. The first two SVD modes together explain >94 % of the covariance between SAT and stratospheric zonal wind anomalies. The leading mode (SVD1) features a pronounced cooling over eastern China, which arises from the combined influence of the quasi-biennial oscillation (QBO) and the downward extension of the stratospheric polar vortex (SPV) over Northeast Asia and the Bering Strait. The second mode (SVD2) exhibits a meridional seesaw pattern of warm and cold anomalies, primarily linked to variations in SPV strength. The differences in the SAT patterns between SVD1 and SVD2 are related to the vertical structure of the QBO and the corresponding Holton–Tan effect. These results highlight the joint influence of the tropical and polar stratosphere on winter SAT in China. 摘要 本文基于JRA-55 再分析资料和CAM6模式, 分析了平流层对中国冬季地表气温 (SAT) 的影响. 利用奇异值分解分析, 揭示了与平流层纬向风相关的SAT主要模态. 其中, 第一主模态在中国东部呈现出显著的降温现象, 该现象源于准两年振荡副热带效应与东北亚-白令海峡上空平流层极涡 (SPV) 信号下传的共同作用. 第二主模态表现为明显的南北振荡, 主要受 SPV 强度变化的调控. 研究结果从热带和极地联动的角度, 揭示了北半球平流层对中国冬季SAT的综合影响.