Impacts of fire-induced heat, moisture, and aerosol-radiation interactions on wildfire plume rise during the 2019/2020 Australian fires

Abstract

Wildfire emissions are a major environmental concern, especially as climate change increases the frequency of extreme events. Our study uses ICON-ART coupled with the widely used Freitas plume-rise model to simulate how accounting for fire-induced atmospheric changes in ICON-ART affects plume rise during the Australian New Year's wildfires of 2019/2020. Simulations were conducted at a 6.6 km grid resolution, where convection is parameterized but fire-induced meteorological effects remain significant. Including fire-induced moisture release in ICON-ART leads to increased cloud formation, but had minimal impact on plume dynamics. In contrast, accounting for fire-induced heat release significantly increased the plume height due to enhanced buoyancy and cloud formation, even without added moisture. Simulating aerosol-radiation interactions initially reduced injection height, as solar absorption by dense aerosols stabilized the atmosphere. However, a lofting effect emerged from the second day onward. The combined simulation-incorporating heat and moisture release and aerosol-radiation interaction in ICON-ART, produced the highest plume rise and best matched satellite observations, including the aerosol layer in the upper troposphere/lower stratosphere. The effects were strongest on the first day, when fire intensity peaked. For less intense fires, the Freitas plume-rise model performed well without additional implementations in the host model.