Theanalysisof43yearsofNCEP-NCARreanalysisdataandstationobservationsrevealstheconnectionsbetweentropospherictemperaturevariationsandtheweakeningoftheIndiansummermonsooncirculation.TheIndiansummermonsoonvariationisstronglylinkedtotropospherictemperatureoverEastAsia,showingsignificantpositivecorrelationsofmeantropospherictemperaturewithall-Indiansummerrainfallandthemonsooncirculationintensity.TheresultshowsthatIndiansummermonsooncirculationunderwenttwoweakeningprocessesinrecentdecades.Thefirstoccurredincircathemid-1960s,andtheotheroccurredincircathelate1970s.ThefindingindicatesthatthemeantropospherictemperaturemayplayacrucialroleintheweakeningoftheIndiansummermonsoonintensityviachangingland-seathermalcontrast.TheroleofthetropospherictemperaturecontrastbetweenEastAsiaandthetropicalareafromtheeasternIndianOceantothetropicalwesternPacificistoweakentheIndiansummermonsooncirculation.
