Abstract:By using the NCAR CAM3 global atmospheric circulation model and NCEP/NCAR reanalysis data, the Sea Surface Temperature Anomaly(SSTA) effects in different sea areas (global, extra-tropical, tropical, tropical Indian ocean-Pacific, tropical Indian ocean and tropical Pacific) on the interdecadal variation of the South Asia High(SAH) were analyzed. Results suggest that the global, tropical, tropical Indian ocean-Pacific and tropical Pacific have great effects on the interdecadol variation of the intensity,area,south,west and east borders of SAH in late 1970s. The tropical Pacific is a key sea area whose third mode of the SSTA has a close association with the interdecadal variation of these SAH indices. The change of SSTA in tropical Indian ocean is associated with the interdecadal variation of the intensity, area, south and west borders of SAH, due to its first mode shown by the in-phase SSTA in tropical Indian ocean, which indicates that this sea area is also a key area in affecting the interdecadal variation of SAH. The main difference between the effects of the tropical Pacific and tropical Indian ocean on the interdecadal variability of SAH is that the former has important effect on the interdecadal variability of eastward extension of SAH and the latter is weaker. The SSTAs in the tropical Pacific and tropical Indian Ocean impact the SAH through affecting the changes of tropical tropospheric temperature driven by these SSTAs. The extra-tropical SSTAs have the weaker impact on the SAH.