Seasonal wildfire aerosols in Southeast Asia and Southern China disrupt the Hadley circulation

Abstract

The impact of wildfires on the economy, climate, and human health is widely recognized. Some of these consequences are due to the influence on precipitation of fire-generated aerosols, especially in hotspots such as Southeast Asia and the southern part of China. The relatively poor understanding of the role of fire-produced aerosols in precipitation motivates us to study the problem in that part of the globe. We utilize multiyear reanalysis and satellite data, as well as cloud-resolving-model simulations with a 2-km horizontal resolution, over large domains extending 4000–5000 km. This combined analysis shows that fire-induced aerosol concentration anomalies perturb the Hadley circulations, which lead to changes in precipitation not only in the immediate fire vicinity, but also distant areas through teleconnections. In the immediate vicinity of the fires, we see suppressed precipitation that can prolong and intensify the fires, while in contrast, the regions located far from the fire sources experience an enhancement in precipitation. This increase in rainfall can delay deforestation and affect ocean salinity, impacting the ecology, climate and economy in those distant regions. Hence, this study demonstrates that beyond the well-established wind-driven transport of aerosols to remote locations, directly impacting human health and visibility, aerosols from fires have additional strong impacts in remote areas by altering circulations and precipitation patterns.