Indian Ocean Sea Surface Temperature Anomaly On The Impact Of Asia's Main Precipitation Area Study

The relationship between Indian Ocean sea surface temperature (SST) and Asiansummer rainfalls is investigated using diagnostic methods and the impactingmechanism is also studied, which include the study of the impact of extratropicalSouth Indian Ocean Dipole (SIOD) on Indian summer monsoon rainfalls (ISMR),Chinese rainfalls and general circulation;investigation of the leading mode of IndianOcean (LMIO) characterized by warming trend of all the basin and its relationshipwith Asian summer rainfalls and summer monsoon circulation and research ofrelationship between LMIO and Pacific SST. Major conclusions are as follows:(1) The warming trend of Indian Ocean SST is significant after 1950s, andthere is abrupt warming in 1976, 1986 and 1996 respectively. Afterevery times of the abrupt warming, Indian Ocean SST remains at ahigher level.(2) The relationship between ISMR and extratropical south Indian OceanSST is rather stable even after the several abrupt warming events,although is changed a lot in other ocean areas, especially in middle andwest tropical Pacific. The SST pattern, when southwest Indian Ocean isnegative (positive) and southeast Indian Ocean positive (negative), isdefined as positive (negative) south Indian Ocean (SIOD). Comparingwith IOD brought forward by Saji, SIOD happens mainly in spring andits variability is more significant than IOD.(3) The relationship between SIOD and ISMR is remarkable. ISMRincreases (decreases) in most of PSIOD (NSIOD) years. The impacts ofSIOD on Chinese rainfalls and subsysterms of Asian summer monsoonare significant too. As a holistic system, both the tropical region andextratropical region have to be taken into account when study theinfluence of Indian Ocean SST.(4) The character of LMIO and relationships between LMIO and Asiansummer rainfalls and circulation are revealed. LMIO characterized bywarming trend of the whole Indian Ocean SST is probable one of themajor factors to weaken Indian summer monsoon and make the rainbellof China shift southward.(5) The trend of LMIO and tropical Pacific SST are usually in phase duringthe climate change process. In the co-variability of global oceans, IndianOcean is very important and should take into account in considering theglobal air-sea interaction. LMIO and Pacific Warmpool have muchcloser relationship, and both significantly contribute to the variation ofglobal surface temperature.