第一届未来大气科学论坛

This study analyzes the response of East Asian surface air temperature (SAT) to the Quasi-Biennial Oscillation (QBO) in boreal winter using the JRA-55 reanalysis dataset and the CAM6 model. East Asian SAT patterns in response to the boreal winter QBO vertical profile are derived from singular value decomposition (SVD) analysis. The leading mode of SVD (SVD1) shows an evident cold center over East Asia, while warm and cold centers show an east-west dipole in the second mode of SVD (SVD2). The corresponding QBO pattern in SVD1 has two opposite centers, with an upper-stratospheric easterly phase and a lower-stratospheric westerly phase; however, there is only one middle-stratospheric westerly center in SVD2. The SVD1-like QBO tends to cause more significant East Asian SAT anomalies than the SVD2-like QBO pattern. This difference originates from the response of the stratospheric polar vortex and the North-Pacific circulation to the QBO. The SVD1-like QBO forces a cyclonic anomaly over the mid-latitude North Pacific and an anticyclonic anomaly over China via a subtropical path and polar path, leading to a zonal pressure gradient and meridional wind anomaly over East Asia. Temperature advection driven by this meridional wind affects cooling and warming over East Asia. By contrast, there are no significant responses to the SVD2-like QBO over the middle latitude North Pacific, and thus, the corresponding East Asian SAT response is weak.

QBO; Surface air temperature; East Asia