A group of U.S. agencies is in the midst of the most detailed study ever done of the enormous plumes of fire-generated smoke that can sometimes cross the entire country before they dissipate.
The goal is to better understand the health, climate and weather impacts of the nation’s increasing volume of wildfires.
“It’s the first really major campaign with fires as its sole focus,” said David Fahey, head of the chemical sciences division at NOAA’s Earth System Research Laboratory.
The agency is working with NASA and the Forest Service on a plan to track wildfire smoke plumes next year in an effort to better identify the thousands of chemicals they contain. Some can impair public health and add to climate problems. Others can affect regional weather as they move.
The culmination of the four-year effort will include another first: a planned burn of a large forested area in the West after an intensive study of the contents of its fuels, including trees, brush, grass and organic matter in soil. The burn will help researchers better measure and understand the specific ingredients of a plume created by an intense fire before it begins to move.
NOAA, NASA, the Energy Department and international agencies have sampled and tracked random forest fire plumes for years, but Fahey noted that the resulting models lack the precise linkages to fuels that will be obtained from a planned fire. The objective is to create a bigger catalog of the materials that end up in the huge airborne cloud of aerosols, gases and dust. That will give scientists a better idea of how the chemistry of smoke evolves as it disperses downwind.
Megan Bela, a scientist at the University of Colorado who is working with NOAA on the study, explained in a lecture last month that scientists still have “fundamental problems” understanding the chemistry of wildfire smoke plumes, which can result in the interaction of “a thousand different chemicals every second.” Some compounds of nitrogen, carbon and other elements in the smoke are destroyed in the reactions, while new ones are created.
One impact is that the models scientists have built—providing information that is also used in satellites the United States employs to spot fires and track plumes—are often wrong, she added. Models often overstate or underrepresent what’s really going on in the plumes.
“You don’t know what’s in the smoke,” Bela said.
It’s not a small problem. Some recent wildfire plumes have originated in the San Francisco area and exited the United States over Boston. Scientists say getting more information about plumes will be important because as the climate warms, fires are expected to grow both in numbers and in size, exposing more people to smoke.
Health impacts can include aggravated asthma, chronic bronchitis, decreased lung function and congestive heart failure. Materials such as brown and black carbon carried by the plumes can also accelerate global warming. Smoke can alter weather by blocking sunlight and influencing cloud formations and precipitation.
The next part of the puzzle is to learn more about how and where the plumes move. Scientists know that some ride on the jet stream, moving thousands of feet above the Earth. But other plumes are much closer to the Earth’s surface, moving so low that parts of them can become trapped in valleys, only to pop up and continue their travel the following afternoon after sunshine has warmed the Earth.
The ongoing study, called Fire Influence on Regional and Global Environments Experiment—Air Quality, or FIREX-AQ for short, started with a series of experiments in 2016 at the Forest Service’s Fire Sciences Laboratory in Missoula, Mont. Scientists sampled smoke from 75 small, experimental fires built from 33 different types of material. New sensors were used to detect the ingredients.
Next summer, some of those sensors will be used in the small airborne fleet of planes that will track the plumes from both the planned fire and other fires that erupt during the height of fire season. The fleet will include a NASA DC-8, a “flying laboratory” carrying 17 different sensors, that will attempt to stay in the middle of plumes and analyze their changes.
Above the plume, an ER-2, NASA’s high-flying version of the former Air Force U-2 spy plane, will carry more sensors. The plane, which can reach altitudes “well above” 70,000 feet, will get a view into the smoke from the same aspect that orbiting satellites have.
At lower altitudes, two smaller planes, both NOAA Twin Otters, will attempt to follow plume flows over the terrain, especially at night, when parts of them cool and sink. That’s part of the puzzle, too, because the ongoing chemical reactions in plumes change at night when sunlight fades and temperatures cool.
Over the summer and fall of next year, the DC-8 and its accompanying fleet will be based in either Idaho or Kansas, depending on fire activity, Fahey said. The overall goal of the FIREX-AQ experiment is to develop and program smarter sensors to help future satellites track the plumes of wildfires and agricultural fires on a 24-hour basis across the globe.
Fahey hopes tracking the planned fire will provide critically needed information about wildfire plumes.
“This will be a world-class collection of instrumentation that should lead to a new understanding of fire emissions’ effects on the atmosphere,” Fahey said.
The results could help scientists better understand far-flung health and climate change hazards, as well as help firefighters get better predictions of fire-caused weather changes that can determine the path of plumes the next day.
“We want to take some of the chaotic elements out of it,” Fahey said. “When you go out into the West, you’re left with nature and chaos in terms of what’s going to burn where tomorrow.”
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.