A Study On The Relationship Between Summer Asian-Pacific Oscillation And East Asian Climate Anomalies

Using the 1948?2016 NCEP/NCAR monthly reanalysis data,the 1948?2010ERA-20 C monthly reanalysis data,the 1948?2012 NOAA monthly reanalysis data,the monthly precipitation data from 839 stations of China during 1960?2016 and the monthly SST data form the COBE-SST and combining statistical analysis method such as empirical orthogonal function(EOF),correlation analysis,composite analysis and regression analysis.the atmospheric teleconnection in the upper and middle troposphere between Asia and Pacific in summer is studied,and its relationship with East Asia climate anomalies and Pacific SST is analyzed.The main conclusions are as follows:(1)Based on the analysis of three reanalysis data,we find that the Asian Pacific Oscillation(APO)is characterized by significant interannual and interdecadal variations,the results of wavelet analysis show that a quasi-three year oscillation period in 2-8 years and a quasi-six year oscillation period in 10-20 years.In addition,the APO showed a weakening of the mutation in 1972,and the climate in East Asia has changed significantly.(2)The summer disturbance potential height between the troposphere of Asia and Pacific is similar to the inverse phase change of the APO.When the summer APO index is high(low),the disturbance potential height is higher(lower)in Asia while it is lower(higher)in Pacific.In addition,when the summer APO index is high,the area of South Asia high pressure over Asian continent is wider,locating partial north,and vice versa.(3)When the summer APO index is high,there is an anomalous anticyclonic circulation over 200 h Pa in East Asia.At this time,both the tropical easterly jet and the mid-latitude westerly jet are strengthened to some extent and the stronger wind at the lower layers indicates that the East Asian summer monsoon is stronger.The precipitation increased in southwest,north,east and northeast China while precipitation decreased with the Huaihe River.Moreover,on the basis of analyzing the correlation between summer APO and Autumn Precipitation in China,we find that summer APO has certain predictive significance for precipitation during autumn.(4)In summer,there is a significant relationship between APO and Pacific SST When the summer APO index is high,SST in North Pacific is abnormally high,while SST in Tropical Middle East Pacific and West Pacific is low,and vice versa.The distribution characteristics of SST is similar to Pacific Decadal Oscillation(PDO).By analyzing the correlation between APO and Ni?o 3.4 index in summer,we find that the relationship between APO and ENSO is not very close in summer due to the fact that APO is located int the northeast.At the same time,the unstable relationship between APO and Pacific SST shows and that relationship is mainly manifested in the unstable change of the relationship between APO and tropical Middle East Pacific SST.This unstable relationship will lead to unstable changes in the correlation between APO and EASM and will affect the climate change in East Asia.