Impacts of Polar Vortex, NPO, and SST Configurations on Unusually Cool Summers in Northeast China.Part Ⅰ: Analysis and Diagnosis

摘要

This study unveils the evolution of two major early signals in the North Pacific atmosphere-ocean system that heralded abnormal high-pressure blockings and cold-vortex activities across Northeast China,based on an analysis of the configurations of major modes including the polar vortex,the North Pacific Oscillation (NPO),and SST in the preceding winter and spring and atmospheric low-frequency disturbances in Northeast China.We analyzed these aspects to understand the atmosphere-ocean physical coupling processes characterized by the two early signals,and here we explain the possible mechanisms through which dipole circulation anomalies affect the summer low-temperature processes in Northeast China.We further analyzed the interdecadal variation background and associated physical processes of the two early signals.