New tool helps predict where wildfire smoke will blow

24 August 2022

Published by: https://www.scientificamerican.com

USA – Scientists are working on ways to better anticipate the pathways—and health dangers—of drifting wildfire smoke

Better satellite coverage of wildfires and improved climate models are giving scientists a more accurate view of smoke plumes as they drift across the country. These kinds of advances, they say, can help provide earlier warnings to residents endangered by wildfire smoke.

A breakthrough in the field occurred during the deadly 2018 Camp Fire in California that killed 88 people, destroyed 19,000 structures and exposed 8 million people in the San Francisco Bay Area to some of the world’s most polluted air for two weeks. Research published in June by the Bulletin of the American Meteorological Society outlines how a new tool helped make the technological leap.

The Camp Fire smoke was so thick in some places, and sparse in others, that legacy prediction systems were “rendered unavailable.” They only could predict “very coarse spatial patterns” or rough estimates where the smoke might be the thickest.

The directions taken by massive smoke plumes are often dictated by the whims of the weather and, in California, steered by the complex terrain of valleys and mountains. Still, there was one system that kept tracking the Camp Fire smoke as it drifted toward San Francisco.

It was an experimental model, put together by data from satellites and supercomputers. It produced a 3D picture predicting the most likely pathway in a given area. Its researchers had been lucky, aided by the fact that it was November and there were no nearby fires to make the problem harder to solve.

The device, called the High-Resolution Rapid Refresh (HRRR) system, failed during the second week when the smoke became so thick that it blocked the infrared radiation that helped two U.S. satellites locate the moving Camp Fire.

But the model gave the scientists who had worked on it a glimpse of a system that might be perfected in future years. “A lot of things needed to be sort of built from scratch,” explained Eric James, a senior researcher with the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado, Boulder.

He worked with a team drawn from NOAA and NASA. They had built a system that provided a clear and accurate 1.16-square-mile view of a given section of the plume and predicted where it was likely to go down the valleys and over the mountains leading to San Francisco.

“The model did a very good job,” said Tina Chow, a professor of engineering at the University of California, Berkeley. She still has vivid memories of the smoke creeping over her campus and shutting it down for four days. “I mean it was bad,” she said. “You could totally smell it, even inside the buildings.”

Chow later helped write the first report on the performance of HRRR, which has been refined and enlarged. It will soon be aided by a new geostationary satellite, GOES-18, which can provide a more constant view of fire-prone areas than two earlier, polar-orbiting satellites could.

The updated smoke-watching system, to be called the Rapid Refresh Forecast System, will cover all of North America, according to James.

“We’re starting to run experimental forecasts in the next few months,” he explained. “The full system will be operational within a couple of years.”

‘Still a lot to uncover’

The next step will be to use the improved tracking system as part of a new study to document the health problems and expenses caused by drifting wildfire smoke. Its researchers hope to develop more reliable ways to warn and prepare people in its pathway.

“It’s our reality here on the West Coast,” explained Neeta Thakur, a pulmonologist and associate professor at the University of California, San Francisco. She is helping to organize the three-year effort, to be financed by EPA.

It will not only address concerns of Californians, but those of millions of other Americans who will be exposed as the smoke drifts eastward.

“We don’t have a good understanding of how to reduce risk across populations and among people who are very susceptible, either medically or due to social circumstances,” Thakur said.

She and other scientists working on the issue noted that the most dangerous ingredients of the smoke are tiny particles that tend to become more spread out and less harmful as the distance increases between the fires and their drifting smoke plumes.

“But there is still a lot to uncover,” Thakur added, noting that the number of emergency room visits in smoke-prone areas will help measure the nature and extent of health problems. Some particles in wildfire smoke are small enough to enter human lungs and the bloodstream. They can cause a variety of health problems such as asthma and lung cancer.

One of the first protective measures the study will test will be to put smoke monitors in the single-room dormitories built to house the homeless in San Francisco. “Older buildings are leakier than new buildings,” she noted, pointing out that outdoor workers, the elderly and people who live in poorer neighborhoods are also less able to reduce their exposure to smoke.

24. August 2022/by GFMCadmin