Interdecadal Variation Of Precipitation In China And The Relative Contributions Of Global Warming, IPO, And AMO To It

In this paper,the trend and interdecadal oscillation change of land precipitation in China during 1934-2018 are explored.We obtain the spatial distribution characteristics of interdecadal precipitation changes and determine the main sea surface temperature(SST)modes that related to the interdecadal variation of precipitation.The relative contribution of the main SST modes to the precipitation change is further analyzed.Finally,the causes of the drought in North China are investigated based on the the relative contribution.The main conclusions are as follows:(1)Singular spectrum analysis(SSA)is used to obtain the areas of significant variability of decadal(10-20 a),multidecadal(20-50 a)and secular trends(>50 a)of summer and winter precipitation in China.(2)Based on Singular Value Decomposition(SVD)analysis of precipitation in China and SST in middle and low latitudes,it is find that global warming(GW)is the main SST mode affecting precipitation in China,Interdecadal Pacific Oscillation(IPO)plays the second role,and the third SST mode is always associated with Atlantic Multidecadal Oscillation(AMO),whether in summer or in winter.(3)The multivariate linear regression model is applyed to quantitatively evaluate the variance contribution and relative contribution of GW,IPO and AMO to precipitation in different regions of China.The results show that GW,IPO and AMO can explain about 30% of the interdecadal precipitation in Northwest China and North China in summer,and the relative contribution of GW is the largest,followed by IPO.In winter,the three factors can explain 42%of the interdecadal precipitation in Northeast China and about 30% of the interdecadal precipitation in Northwest China and North China.In Northeast China and Northwest China,the relative contribution of GW is dominant,AMO plays a role only secondary to it.While in North China,GW is dominant,IPO plays a role only secondary to GW,no matter in summer or winter.(4)Based on the results of relative contribution,the causes of the drought in North China are explored.The decrease of summer precipitation in North China is mainly influenced by GW trend,IPO plays a second role.In summer,both the GW trend and the IPO in the positive phase can cause the northerly wind and downdraft in North China and so the precipitation decrease.Finally,the mechanism of IPO influencing summer precipitation in North China is verified by the hist＿res IPO experiment of Global Monsoons Model Inter-comparison Project in the Coupled Model Intercomparison Project Phase 6(CMIP6).