The Characteristics Of Decadal Variability Of Silk Road Pattern And Its Relationship With East Asian Summer Monsoon

The Silk Road Pattern(SRP)exists in the upper troposphere over the mid-latitudes of AsiaEurope in the Northern Hemisphere.Based on several reanalysis datasets,we analyzed SRP mode and principal component's decadal change characteristics,discussed the relationships between SRP and East Asian Summer Monsoon(EASM)and sought the influences of the external force factors such as Sea Surface Temperature(SST)and Sea Ice Concentration(SIC)on SRP on decadal time scale.The results show that(1)SRP has significant annual and decadal variations.On decadal time scale,from the 1950 s to the mid-1970 s and from the late 1990 s to the present(the mid-1970 s to the late 1990s),it was mainly in the negative(positive)phase;(2)SRP is significantly related to the EASM on the decadal time scale and when SRP is on positive(negative)phase,air temperatures in the East Asian continent decreases(increases),precipitation in North China and Northeast China increases(decreases),precipitation in the middle and lower reaches of the Yangtze River,the Korean Peninsula,and Japan decreases(increases),and the intensity of the Western Pacific subtropical high decreases(increases),the EASM is weaker(stronger);(3)On the decadal scale,the anomalous TN flux caused by the SPR and the anomalous air temperature caused by the anomalous meridional winds in the lower troposphere of East Asia may be the reasons for the changes of the intensity of the EASM.(4)Pacific Decadal Oscillation(PDO),Atlantic Multidecadal Oscillation(AMO)and the sea ice in the Beaufort Sea have significant influence on SRP on the decadal time scale.They are important precursors to SRP on decadal time scale.