Validation brings new predictive capability t


image: Recent megafires in Australia and British Columbia injected unprecedented amounts of smoke into the stratosphere. Modeling led by Los Alamos National Laboratory will help predict the effects of similar future events.
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Credit: David Peterson, FIREX-AQ

New research modeling smoke from two recent megafires sets the stage for better prediction of how emissions from these events on a global scale will behave and affect temperatures. As huge wildfires become more common with climate change, increased attention has focused on the intensity and duration of their emissions, which rival those of some volcanic eruptions.

Megafires in British Columbia in 2017 and Australia in 2019-20 injected massive amounts of smoke into the stratosphere, enabling the first-ever detailed satellite and ground-based measurements of such cataclysms. Using this data for validation, a team led by Los Alamos National Laboratory modeled the behavior and impacts of smoke as it rose from the lower atmosphere into the upper stratosphere and then circulated around the world. The research appeared in the Journal of Geophysical Research – Atmospheres.

“This is the only time we have tracked the smoke phenomenon on a global scale with satellite and ground observations, allowing us to improve the model and understand the impact,” said Manvendra Dubey, chief of project and co-author of the article. published this week in the Journal of Geophysical Research: Atmospheres. “Models and metrics combine to improve predictability.”

“As fire regimes shift and enter new paradigms of behavior in the face of future climate change, data from past fires cannot be used for prediction and assessment,” said Gennaro D’Angelo, co- author of the article and researcher at Los Alamos. .

“Models are the only way to predict their smoke effects,” Dubey said. “For example, observations from the Australian fire showed that black carbon was stimulated by solar heating and rose 30 kilometers into the stratosphere, causing the plume to last longer, around 16 months. Our model accounts for this self-heating phenomenon predicted by the late Robert C. Malone at Los Alamos in the 1980s – and our new study unequivocally validates it.

Plumes have a cooling effect

Australia’s 2019-2020 megafire injected huge amounts of smoke and soot into the atmosphere that have been observed, with global temperature impacts, as shown in this study. The shadowing of the Australian plume lasted for a few months. This effect lowered temperatures in the Southern Hemisphere by about 0.2 degrees Celsius, information that has implications for models of global climate change.

The smaller plume from the 2017 fires in British Columbia did not trigger a similar cooling. The study highlights when and how smoke from megafires affects the global climate, just as injections of volcanic sulfate and ash do.

Paper: “Contrasting Stratospheric Smoke Mass and Lifespan of the 2017 Canadian and 2019/2020 Australian Megafires: Global Simulations and Satellite Observations”, by Gennaro D’Angelo, Steve Guimond, Jon Reisner, David A. Peterson and Manvendra Dubey in the Journal of Geophysical Research: Atmospheres.

Funding: This research was funded by the Los Alamos Laboratory-led Research and Development Program.


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