Relative Contributions Of Global Warming,AMO And IPO To The Changes Of Land Precipitation

According to the observational data and atmospheric general circulation model(AGCM),we investigated the trends and interdecadal changes of land precipitation during 1934-2015,and further explored the relative contribution of sea surface temperature modes to the changes of JJA and DJF land precipitation.In this paper,the main results are as follows:1.By performing SVD analysis upon the tropical land precipitation and sea surface temperature(SST),we identify three dominant ocean modes: global warming(GW),Atlantic Multidecadal Oscillation(AMO)and Interdecadal Pacific Oscillation(IPO),which effect the trend/interdecadal variation of land precipitation.Our results show that the GW is the first mode no matter in JJA or DJF season.AMO(IPO)is the second mode in JJA(DJF).2.Using linear multi regression method,we quantitatively assess the relative contribution of GW,AMO and IPO to the land precipitation variation in different regions.The contribution of GW,AMO and IPO to land precipitation are equivalent in latitude bands:10?S-10?N,50?N-60?N and 40?S-50?S in JJA.Beyond these latitude belts,GW and AMO are the two dominant contributors in JJA.In DJF,IPO play a dominant role in latitude band:20?S-40?N.Beyond 20?S-40?N,GW play a dominant role to the land precipitation changes.GW contribute most to the changes of land precipitation over many regions,such as the northeastern North America and Asia in JJA,Europe in DJF.AMO impacts most over the Sahel,Siberia,and South America in JJA.IPO impacts most over the southwestern United States.In addition,northeastern North America and northwestern South America,southern Africa,East Australia,South Asia monsoon region and North China are also affected by IPO in DJF.3.We also use the atmospheric general circulation model(AGCM)ECHAM 4.6 to further identify the effect of Pacific and Atlantic SST anomalies(SSTA)on the land precipitation variation and the results suggest that the SSTA over the Indian Ocean is indispensable in the role of AMO and IPO on land precipitation changes.