The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

In this study, the strengthening of Somali Jet (SMJ) intensity is major responsible for an increase of summer precipitation over the Tibetan Plateau (TP) after 1998 is pointed out. Firstly, a transition of the summer precipitation over the TP from a negative anomaly during 1979-1997 (P1) to a positive anomaly during 1998-2022 (P2) is identified. The water vapor budget analysis then shows that the interdecadal increment of summer rainfall over the TP is mainly attributed to the concurrent increase of water vapor inflow through the southern boundary and the decrease of water vapor outflow through the eastern boundary after 1998. The results indicate that more moisture sources from East Asia and the Indian Ocean, especially over the tropical western Indian Ocean where the SMJ is located during P2. Further analysis reveals that the strengthening of SMJ intensity in summer directly causes the increase of southerly water vapor influx over the TP, while the enhancement of SMJ intensity in spring serves an indirect role in reducing the easterly water vapor outflux in summer by leading the East Asian Westerly jet poleward after 1998.

Indian Ocean,Somali Jet,Tibetan Plateau precipitation,moisture transport,interdecadal change

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