Global monsoon precipitation responses to large volcanic eruptions

Predictionof global monsoon (GM) changes is important for infrastructure planning and sustainable economic development. Here, we focus on strong volcanic forcing since large eruptions are known to be a dominant mechanism in natural climate changes. However, issues remain unexplored: Is the global monsoon able to be changed significantly by large volcanic events? Do large volcanoes erupted at different latitudes have distinctive effects on the GM in the Northern Hemisphere (NH) and Southern Hemisphere (SH)? We address these issues using a 1500-year volcanic sensitivity simulation with the Community Earth System Model version 1.0 (CESM1). Volcanoes are classified into three types based on their meridional aerosol distributions: NH volcano, SH volcano and equatorial volcano. We show that the GM precipitation is reduced by volcanic eruptions significantly. The NH (SH) volcanic eruptions are more efficient in reducing the NH (SH) monsoon precipitation than the equatorial ones, because the subtropical-extropical volcanic events have strong impacts on both moisture and atmospheric circulation, while the equatorial ones only reduce moisture and do not strongly affect the circulation. Surprisingly, the NH (SH) monsoon precipitation is enhanced significantly (95% confidence) by the SH (NH) volcanic eruptions, and this intensification is mainly though circulation change.