Persistent Stratospheric Warming due to 2019-20 Australian Wildfire Smoke

Abstract:

Australian wildfires burning from 2019-2020 injected the largest amount of smoke into the stratosphere observed in the satellite era, about 0.9 Tg, which is 3 times the amount of the smoke injected from the 2017 Pacific Northwest wildfire event. Satellites observed the smoke plume rose to about 25 km and spread over most of the Southern Hemisphere within 2 months. We conducted numerical simulations to further probe the plume rise, transport, chemical properties, and radiative effects of the wildfire smoke. The simulation suggests that black carbon composed 2.5% of the total smoke mass. The black-carbon containing smoke could remain in the stratosphere for over one year, and measurably warms the mid-latitudes of the Southern Hemisphere stratosphere by 1-2 K for about 6 months. Simulations suggest that the smoke particles can bring ozone changes of 5-7 Dobson units from July to December in high latitudes of the Southern Hemisphere, assuming smoke particles have similar heterogeneous reaction rates as sulfate aerosol.