Research on the Interannual Variation Characteristics of the Causal Relationship between the Northern Hemisphere Annular Mode and Northeast Asia Winter Surface Air Temperature Based on Convergent Cross Mapping Method

The Northern Hemisphere Annular Mode (NAM) is the main circulation mode in the Northern Hemisphere in winter, with a significant impact on the winter climate variability in the Northern Hemisphere. There are a number of studies that use statistical methods such as correlation analysis and synthetic analysis to discuss NAM and other climatic factors but rarely with the perspective of causality. In this research, the authors apply the Convergent Cross Mapping (CCM) method and use the NAM index provided by the Climate Prediction Center (CPC) from 1960 to 2018 as well as reanalysis data provided by NCEP/NCAR to analyze the impact of NAM on the winter Surface Air Temperature (SAT) in Northeast Asia. Causality changes its strength and weakness year by year and its possible physical mechanism. Our analysis indicates the following: 1) NAM has a one-way causal relationship with the winter SAT in Northeast Asia, and the strength of the relationship has interannual changes. The maximum and minimum years of causal effects are 2006 and 1982, respectively. 2) The winter NAM index has a significant 8−9-year scale main cycle, which is the driving factor for the winter NAM to affect the SAT in Northeast Asia, and to some extent, its change has affected the interannual change of NAM on the SAT causality in Northeast Asia. 3) Comparing the circulation situation of the maximum (2006) and minimum (1982) years of the causal relationship of the impact of NAM on the SAT, it can be seen that the “seesaw” structure of NAM in the year of maximum causality (2006) is obvious. However, the form of NAM’s north–south oscillation in the year of minimum causality (1982) is not obvious. This work may therefore provide a new idea in analyzing the interannual and inter-decadal changes of causality.