Simulating the Impact of Bushfires in Australia on Local Air Quality and Aerosol Burden in the Southern Hemisphere

Abstract

From the end of 2019 to the beginning of 2020, Australian bushfires caused by high temperatures and drought significantly impacted the local and global atmosphere. This work uses the global atmospheric chemistry transport model and observations to assess the enormous impact of bushfire emissions on PM2.5 in Australia. During December 2019, the significant increase in biomass-burning emissions led to increases in PM2.5 observations in megacities such as Canberra, Sydney, Newcastle, Brisbane and Melbourne by 845%, 322%, 171%, 141% and 58%, respectively. Numerical simulations reveal that bushfires increased PM2.5 in Australia and in the Southern Hemisphere by 49% and 13%, respectively. Although the aerosols produced by bushfires could not cross the equator at ground level and affect the air quality in the Northern Hemisphere, they were transported to South Asian countries such as Malaysia and India, as well as Papua New Guinea and New Zealand. In addition, they were also injected upward into the stratosphere (approximately 15 km height). Aerosols injected into the stratosphere could be transported to Antarctica and South America, thus completing global transport.