Difference in the influence of Indo-Pacific Ocean heat content on South Asian Summer Monsoon intensity before and after 1976/1977
2016
Dong, Yujie | Feng, Junqiao | Hu, Dunxin
Monthly ocean temperature from ORAS4 datasets and atmospheric data from NCEP/NCAR Reanalysis I/II were used to analyze the relationship between the intensity of the South Asian summer monsoon (SASM) and upper ocean heat content (HC) in the tropical Indo-Pacific Ocean. The monsoon was differentiated into a Southwest Asian Summer Monsoon (SWASM) (2.5°–20°N, 35°–70°E) and Southeast Asian Summer Monsoon (SEASM) (2.5°–20°N, 70°–110°E). Results show that before the 1976/77 climate shift, the SWASM was strongly related to HC in the southern Indian Ocean and tropical Pacific Ocean. The southern Indian Ocean affected SWASM by altering the pressure gradient between southern Africa and the northern Indian Ocean and by enhancing the Somali cross-equatorial flow. The tropical Pacific impacted the SWASM through the remote forcing of ENSO. After the 1976/77 shift, there was a close relationship between equatorial central Pacific HC and the SEASM. However, before that shift, their relationship was weak.
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