Displacement of Intertropical Convergence Zone induced by interannual variability in biomass burning aerosol emissions

Abstract Biomass burning (BB) aerosols affect Earth’s climate through total emissions and their interannual variability. Using the Community Earth System Model version 2 Large Ensemble Community Project, we investigate the impact of BB variability on the tropical climate response. High BB variability leads to increased precipitation and a southward shift of the Intertropical Convergence Zone (ITCZ) in the central Pacific (CP) and western Pacific (WP), but reduces precipitation and causes a northward ITCZ shift in the eastern Pacific (EP) and the Atlantic Ocean (AO). This ITCZ displacement is associated with the north–south tilt of the Walker circulation. High variability increases cloud cover over the CP and WP, which induces negative outgoing long-wave radiation (OLR) anomalies in the Southern Hemisphere. Lower OLR values cause cross-equatorial heat transport and lead to a southward ITCZ shift. Conversely, cloud thinning corresponds to higher OLR values and a northward ITCZ shift in the EP and AO. Our results unravel the mechanisms linking BB variability and large-scale circulation through aerosol–cloud–radiation interactions.