The Causal Relationship Between The Northern Hemisphere Annular Mode And Winter Temperature In Northeast Asia And Its Application In Forecasting

The Northern Hemisphere Annular Mode(NAM)is the main mode of internal climate variability in the Northern Hemisphere.NAM has a huge impact on the weather and climate in North America,Europe and Asia.Different from previous studies,this article discusses the causal relationship,the change of the causal relationship,the strength of interaction,and the strength of the interaction between NAM on the winter SAT in Northeast Asia from the perspective of causality,using the Convergent Cross Mapping(CCM)algorithm and the S-map algorithm.Utilizing the application of CCM algorithm in prediction,adding NAM signal to the reconstructed phase space of SAT to improve its prediction,providing new ideas for future research.The main conclusions are as follows:(1)There is a one-way causal relationship between NAM and winter SAT in Northeast Asia.NAM has always been an influencing factor for the changes in winter SAT in Northeast Asia,but the strength of the causal relationship is not static.There were obvious oscillations between 1960 and 2018.The interannual(decadal)change characteristics of the SAT,2006 and 1982 were the maximum and minimum years of NAM's influence on the SAT in Northeast Asia.(2)There is a significant 8-9 year main period oscillation in NAMI in winter,and the change of its envelope signal is the driving factor of NAM's influence on SAT in Northeast Asia in winter.The magnitude of its change affects the causality of NAM on SAT in Northeast Asia to a certain extent.The size of the relationship.(3)In the mid-to-high latitudes and polar regions of the year with high causality,the 500 h Pa geopotential height field presents a "seesaw" structure with a low north and a high south.NAM is stronger than usual,and the temperature in Northeast Asia is greatly affected by NAM;and The strength of causality is small,and NAM is weaker than normal.The temperature in Northeast Asia may be affected by NAM and other systems.(4)When using univariate,multivariate and multi-perspective embedding methods for prediction,the predictive capabilities of the three methods are as follows: multi-perspective embedding method> multivariate embedding method> univariate embedding method.Using the characteristics of common information in the variables in the complex system,and under certain time series,using the complexity of the winter dynamic system to increase the information in the system,adding NAM to the reconstructed state space of the SAT can improve the prediction effect of the SAT.(5)The interaction between variables in the same system is not constant,but constantly changes as the system transitions to a new state.The S-map method can be used to quantify the changing interactions between variables in a given system.The length of the time series L has a certain influence on the results of the interaction strength.When using the S-map algorithm to calculate the interaction strength between variables,try to choose a sequence with a sufficiently long time series.(6)Regarding Northeast Asia SAT,NAM signals,and Asian polar vortex as different factors in the same climate system,calculate the interaction between NAM,polar vortex intensity and Northeast Asia winter SAT.The interaction between NAM and SAT is mostly positive,indicating that SAT increases with the increase of NAM;while the interaction between polar vortex strength and SAT is the opposite.In addition,the interaction strength between NAM and SAT and the interaction between polar vortex and SAT are reversed.Both polar vortex strength and NAM have greater interaction with SAT in East Asia in the winter half of the year.