Different Effects Of Tropical Atlantic SST Anomalies On Spring Climate In Eurasia During 1970-1995 And 1996-2018 Springs

The variation of spring tropical Atlantic sea surface temperature anomalies(SSTAs)during the period of 1961-2018 and different impacts on Eurasian spring climate before and after the warming of the tropical Atlantic in spring are investigated based on NCEP/NCAR reanalysis data set,NOAA monthly mean sea surface temperature(SST)extended reconstruction data and University of Delaware monthly precipitation and surface temperature data,by using statistical diagnosis methods,such as composite analysis,regression analysis etc.,together with the Community Atmosphere Model(CAM),and its possible causes was also discussed.The main conclusions are as follows:(1)During the study period show that the large spring tropical Atlantic SST variance mainly occurred over the northeastern tropical Atlantic,and the SSTA shows an interdecadal variation,with an abrupt warming around 1995.In addition,the tropical Atlantic SSTA may be maintained by local air-sea interaction via the W-E-S mechanism.(2)Distinctive impacts of spring tropical Atlantic SSTAs on Eurasian spring surface air temperature(SAT)and precipitation during the period 1970-1995 and 1996-2018 are revealed.In terms of temperature,spring tropical Atlantic SSTAs were highly correlated with Eurasian temperature anomalies over Northern Europe,Southeast China,and Indochina Peninsula during1970-1995.These high correlations disappeared during 1996-2018;instead,high correlations dominated over North-Northeastern China,and Central Siberia in spring.The high correlation patterns between spring tropical Atlantic SSTAs.Spring Eurasian precipitation of these two periods also differed,which changed from positive anomalies to negative anomalies over the Indochina Peninsula and Central Asia around 1995.Negative precipitation anomalies in the northwest Europe disappeared and the positive precipitation anomalies in the Northeast China became more significant after 1995.(3)The interannual relationship between spring tropical Atlantic SSTAs and Eurasian SAT/precipitation during 1996-2018 was mainly due to the existence of an anomalous atmospheric wave train across the tropical Atlantic and Eurasia,which was absent during 1970-1995.In addition,given the same SSTAs,the resultant positive anomalies in surface heat flux and precipitation would be larger under a warm SST background fields because of the change of basic state.This would lead to the anomalous atmospheric wave train from the tropical Atlantic to Eurasia under the warm SST background field,which is absent under the cold SST background filed.