Possible impact of biomass burning aerosols over Indo-China Peninsula during normal and El Niño years

In this work, we do statistical analysis used MERRA2 reanalysis data from 1980 to 2017 to investigate aerosol effects from biomass burning (BB) emissions in Indo-China Peninsula and its potential combined impact with ENSO conditions. Longer-lasting and higher BB emissions more likely occur under an El Nino condition when it's also good for transporting them downstream. Aerosols in El Nino years make amplified radiative forcing, with negative on the top of atmosphere and surface and positive in the atmosphere. BB aerosols lead to suppressed precipitation both locally and downstream in March to April except increasing rainfall over South China in May. Under combined impact with El Nino, circulation is changed and an anomalous meridional circulation over Indochina is induced, along with stronger southwesterly winds toward southern China, which lead to less rainfall over southern emission region but enhanced rainfall over northern slope and downstream around southern China. This may remain till early summer monsoon season. Sensitive experiments using WRF-Chem model are also conducted to further investigate the mechanism of aerosol effects.