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A 600-year integration performed with the Bergen Climate Model and National Centers for Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR) reanalysis data were used to investigate the impact of strong tropical volcanic eruptions on the East Asian summer monsoon(EASM) and EASM rainfall. Both the simulation and NCEP/NCAR reanalysis data show a weakening of the EASM in strong eruption years. The model simulation suggests that North and South China experience droughts and the Yangtze–Huaihe River Valley experiences floods during eruption years. In response to strong tropical volcanic eruptions, the meridional air temperature gradient in the upper troposphere is enhanced, which leads to a southward shift and an increase of the East Asian subtropical westerly jet stream(EASWJ). At the same time, the land–sea thermal contrast between the Asian land mass and Northwest Pacific Ocean is weakened. The southward shift and increase of the EASWJ and reduction of the land–sea thermal contrast all contribute to a weakening of the EASM and EASM rainfall anomaly.
A 600-year integration performed with the Bergen Climate Model and National Centers for Environmental Prediction / National Center for Atmospheric Research (NCEP / NCAR) reanalysis data were used to investigate the impact of strong tropical volcanic eruptions on the East Asian summer monsoon (EASM) Both the simulation and NCEP / NCAR reanalysis data show a weakening of the EASM in strong eruption years. The model simulation suggests that North and South China experience droughts and the Yangtze-Huaihe River Valley experiences floods during eruption years. In response to strong tropical volcanic eruptions, the meridional air temperature gradient in the upper troposphere is enhanced, which leads to a southward shift and an increase of the East Asian subtropical westerly jet stream (EASWJ). At the same time, the land-sea thermal contrast between the Asian land mass and Northwest Pacific Ocean is weakened. The southward shift and increase of the EASWJ and reduction of the lan d-sea thermal contrast all contribute to a weakening of the EASM and EASM rainfall anomaly.