Wildfire research has become increasingly important in recent years as climate change has made fires more frequent and intense. But smoke from wildfires could have a bigger effect on the climate than previously thought. Wyoming Public Radio’s Ivy Engel spoke with Shane Murphy, a University of Wyoming researcher who has studied the smoke inside plumes.
Shane Murphy: So basically we operated from the C-130 aircraft, which N-CAR uses. So I don’t know if you know the C-130, it’s a giant cargo plane, and so we fill the C-130 with instrumentation. Each university brings its own suite of instruments and so when we wrote the grants we determined what teams we would need, what instrumentation we needed to achieve the smoke gas and particulate analysis objectives in the smoke, and how the smoke impacts the clouds. And so all the teams are working together to try to answer these big scientific questions. So the project actually had this big field deployment in Boise in the summer of 2018, and the science is just coming out now because it takes a long time to analyze all this data and stuff.
Ivy Engel: Could you describe what the interior of the plane looks like? Because it looks quite cramped.
SM: Imagine a big house. And you have to fill that with instrumentation. And then once all that instrumentation is there, you’re right, there’s just an aisle left in the middle for you to go up and down. And then pretty much the whole rest of the plane is stuffed full of instruments with a bit of room for the scientist to sit down, turn around and operate it. And then at the front of the plane, a research scientist, so it would vary from flight to flight, will be leading the flight. So we will have a plan on fire that we will continue, then during the flight we will watch the images in real time from the satellites. And so the people on the ground are analyzing that data as it comes in and telling us where to go and how to adjust, and then the flight scientist up front will communicate with the pilots and say, “it looks well or turn here, or we want to measure this part of the plume, and the pilots are really competent.
THAT IS TO SAY: It must be crazy.
SM: You would think that would be scary. But it’s actually not very scary because the N-CAR drivers are so skilled, they’re really, really well trained, and so they’re always on top. And generally the way we operated was that the flight controllers would give us a piece of airspace where we could operate, away from any firefighting operations or air traffic. Because when you’re in the smoke, you often can’t see, so we often operate under what you call instrument flight control rules instead of visual flight control rules, because the smoke is so thick, it’s like flying in a cloud.
THAT IS TO SAY: It’s so cool. So how far would you go to get to a fire to test it?
SM: Long paths. So we were based in Boise because that stuff tends to be in the center of the area that could burn. And if you remember back in 2018, almost the entire western United States was on fire. So we measured the fires in California, Oregon, Washington, Utah, Montana, Wyoming, we may have snuck in. The plane can stay in the air for about eight, eight to nine hours. So yes, it’s a bit tiring to sit on the plane for eight hours. What people often don’t realize is that when you take a commercial plane, they’re flying very high, one, and they’re also signaling to each other where the turbulence is. And in these projects we often fly low because we want to be in the smoke and there’s no reporting of where the turbulence is, so it tends to be quite turbulent relative to what what you think of a commercial flight.
THAT IS TO SAY: My God, I can imagine. And, I mean, fires create their own weather anyway.
SM: Absoutely. And that’s something we had to be very careful about. So where the fire is active we couldn’t measure just above the fire because the plume from the fire can be very intense with really huge updrafts, as bad or worse than a thunderstorm . And it can actually damage the plane. So we stayed away from where the fire was burning and started measuring a few miles downwind.
THAT IS TO SAY: Brown carbon, how does this relate to the different reflectivity of smoke particles? Is it just part of the color spectrum?
SM: Yes, no, that’s a great question. So imagine you are at your campfire. And sometimes your campfire will give us this really black smoke when maybe it burned a log and it’s really hot, you’ll just see this black soot coming off. And other times, maybe you have some wet wood or stuff, you’ll push that really white, puffy smoke away. And all the rest. So you can imagine a forest fire, you have all these particles emitted. And so for a long time people thought that the only thing that was absorbing sunlight was black carbon and all that kind of reflected light. But now we have learned that there is this kind of intermediate substance which we call brown carbon. And it’s not a very scientific name, it’s just you know, the soot is black, the rest is white, and it’s somewhere in between, so it’s kind of brownish. And so, people have recently realized that this has been a big problem for the past 10 years. And then they realized it doesn’t last forever. And everything is mixed together, everything is in the same particles, and this substance tends to absorb certain wavelengths of light and not to absorb other wavelengths of light. And so it’s complicated in that sense, and then also, as it reacts in the atmosphere, it disappears. And so really honing in on that is important, because if it goes on for a long time, the smoke from the wildfires will have a more warming effect. If it lasts less, the smoke from wildfires will have a more cooling effect. So you have to understand what wavelength of light it absorbs and how long it lasts in the atmosphere, and that depends on all sorts of things. But it lasts a day or two in the atmosphere and we have a lot of good measurements of how much it absorbs blue light versus red light. And so yes, we have added quite a bit of information on these two topics.
THAT IS TO SAY: Okay. So what can we do with this information? Is it knowledge for knowledge’s sake, or is it something we can do?
SM: In short, what you’re doing with this stuff is you’re comparing it to models. And what we found was that most climate models assumed that the smoke emitted from the fires was much more absorbing than the measurements showed. So you improve the models, and then the models do a better job of predicting future climate. And so I think the net gain is that we get a better estimate of what the climate will be like in 10, 20, 30 years, so that we can plan better. We understand if there is going to be more warming or cooling, and can react accordingly.
