Reply on RC2

Abstract

Explosive volcanic eruptions affect surface climate especially in monsoon regions, but responses vary in different regions and to volcanic aerosol injection (VAI) in different hemispheres. Here we use six ensemble members from last millennium experiment of the Coupled Model Intercomparison Project Phase 5, to investigate the mechanism of regional hydrological responses to different hemispheric VAI in the Asian monsoon region (AMR). It brings a significant drying effect over the AMR after northern hemisphere VAI (NHVAI), spatially, a distinct “wet get drier, dry gets wetter” response pattern emerges with significant drying effect in the wettest area (RWA) but significant wetting effect in the driest area (RDA) of the AMR. After southern hemisphere VAI (SHVAI), it shows a significant wetting effect over the AMR, but spatial response pattern is not that clear due to small aerosol magnitude. The mechanism of the hydrological impact relates to the indirect change of atmospheric circulation due to the direct radiative effect of volcanic aerosols. The decreased thermal contrast between the land and the ocean after NHVAI results in weakened EASM and SASM. This changes the moisture transport and cloud formation in the monsoon and westerlies-dominated subregions. The subsequent radiative effect and physical feedbacks of local clouds lead to different drying and wetting effects in different areas. Results here indicate that future volcanic eruptions may alleviate the uneven distribution of precipitation in the AMR, which should be considered in the near-term decadal prediction and future strategy of local adaptation to global warming. The local hydrological responses and mechanisms found here can also provide reference to stratospheric aerosol engineering.