TheIndianOcean(IO)seasurfacetemperature(SST)wasanalyzedbyusingempiricalorthogonalfunction(EOF),andtheleadingmodeofIndianOcean(LMIO)SSTwasextracted.ThemajorspatialandtemporalcharactersofLMIOwerediscussed,andtherelationshipsbetweenLMIOwithIndiansummermonsoon(ISM)andwithChinasummerrainfalls(CSR)wereinvestigated,thentheimpactsofLMIOonAsiansummermonsoon(ASM)circulationwereexplored.Somenotableresultsareobtained:ThesignificantevolutionalcharactersofLMIOaretheconsistentwarmingtrendofalmostthewholeIObasin,thedistinctivequasi-3-andquasi-11-yroscillationsandremarkablyinterdecadalwarmingin1976/1977and1997/1998,respectively.TheLMIOimpairedthelowerlevelcirculationofISMandwascloselyrelatedwiththeclimatetrendofCSR.ItwasassociatedwiththeweakeningofSouthAsianhigh,theeasterlywindssouthoftheTibetanPlateau,andthecross-equatorialflowsover10°-20°N,40°-110°Eattheupperlevel;withthestrengtheningofSomalicross-equatorialjetbuttheweakeningofthecirculationofISMinthesectorofIndia,thestrengtheningofsouthwindoverthemiddleandlowerreachesofYangtzeRiverandSouthChinabuttheweakeningofsouthwesterlywindsoverNorthChinaatlowerlevelandwiththeincreasingofsurfacepressureovertheAsianContinent.ChangesinthemoisturefluxtransportsintegratedverticallyoverthewholetroposphereassociatedwithLMIOaresimilartothoseinthelowerlevelcirculation.Tosumup,thesignificantSSTincreasingtrendofIObasinwasoneoftheimportantcausesforweakeningoftheASMcirculationandthesouthwardsshiftingofChinasummerrainband.
