UW researchers discover that wildfire smoke makes the local weather cooler than pc fashions – do you suppose so?

From the University of Wyoming

January 12, 2021

The UW Mobile Lab measured the burning smoke from biomass in Wyoming several years ago. This is an example of the type of field measurement used to compare against the computer models. Hunter Brown, a recently completed UW Ph.D. The atmospheric science graduate was the lead author of a paper that revealed that smoke from forest fires has more of a cooling effect on the atmosphere than computer models assume. (Rachel Edie photo)

A study of aerosols used to burn biomass by researchers at the University of Wyoming found that smoke from forest fires cools the atmosphere more than computer models assume.

“The study looks at the effects of forest fires on global climate and we have used the NCAR Wyoming (Cheyenne) supercomputer extensively,” said Shane Murphy, associate professor of atmospheric science at UW. “The paper also used observations from UW and other teams around the world to compare them to the results of the climate model. The main conclusion of the work is that forest fire smoke is cooler than current models assume. “

Murphy was a contributing author of a paper titled “Aerosols Used to Burn Biomass in Most Climate Models Absorb Too Much,” which was published Jan. 12 (today) in Nature Communications, an open access journal that publishes high quality research published from all areas of the natural sciences. Articles published by the journal represent important advances that are important to those skilled in any field.

Hunter Brown, who received his PhD in Atmospheric Science from UW in Fall 2020, was the paper’s lead author. Other authors on the paper included researchers from Texas A&M University; North Carolina A&T State University; the University of Georgia; the Finnish Meteorological Institute; the Center for International Climate and Environmental Sciences and the Norwegian Meteorological Institute in Oslo, Norway; the University of Reading in the United Kingdom; Northwest University in South Africa; the University of Science and Technology of China in Hefei, China; and Pacific Northwest National Laboratory in Richland, Wash.

The composition, size and the state of the mixture of aerosols for the combustion of biomass determine the optical properties of smoke plumes in the atmosphere, which in turn have a significant influence on how these aerosols disturb the energy balance in the atmosphere.

“We found that many of the most advanced climate models burn aerosols or smoke that is darker or more light-absorbing than what we see in observations,” says Brown of Juneau, Alaska. “This has an impact on the climate predictions of these models.”

The National Science Foundation / National Center for Atmospheric Research (NSF / NCAR) C-130 aircraft measure smoke from biomass during the WE-CAN (Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption and Nitrogen) field campaign in 2018. (Shane Murphy Photo)

The observations and models used in the study covered a wide time range. In addition to boreal fire regions, Africa, South America and Southeast Asia were selected because these are the world’s largest contributors to smoke emissions when burning biomass, according to Brown.

The National Center for Atmospheric Research (NCAR) – Wyoming Supercomputing Center (NWSC) in Cheyenne was used for all of the data processing and model sensitivity simulations, Brown says. Some of the other model data used for comparison in this study was generated elsewhere.

“If we compare global observations of forest fire smoke with simulated forest fire smoke from a collection of climate models, the vast majority of the models have smoke that absorbs more light than the observations,” explains Brown. “This means that more energy from the sun in these models is heating the atmosphere, contrary to what we see in these field campaigns and laboratory studies where less absorbing smoke is reported, which has a greater cooling effect by scattering the light on the earth and back to space. ”

The extent to which these aerosols are absorbed in the atmosphere depends on the type of fuel being burned and the climate in the region of the fire. In general, hot, dry grassland fires in Africa and Australia tend to have much darker smoke that is more absorbent, while cooler, more humid boreal forest fires in North America and Northern Asia tend to have much lighter smoke that is less absorbent.

Full article here.

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