 Hello everyone, from wherever you're joining. Thank you for being here today for this NCAR Explorer series conversation, how weather and wildfires interact insights from aerosols in sub-Saharan Africa with Dr. Rebecca Bocchols and Dr. Osinachi Ajocu. My name is Dr. Abby McComber, and I am an educational designer for the NCAR Explorer series. The National Center for Atmospheric Research, or NCAR, is a world-leading organization dedicated to understanding Earth system science, including our atmosphere, weather, climate, the sun, and the importance of all of these systems to our society. I am really glad to be with all you all today. For this conversation, we will take questions throughout the event. So please submit any questions you might have using the Slido platform. If you scroll down this webpage, you can see the Slido window just below where you are seeing the live stream video of this event. If you haven't already, go ahead and click on the green join event button. And then you can ask questions on the Q&A tab and answer poll questions on the poll tab, both of which are found in that blue bar across the top. And definitely, be sure to join Slido to add your thoughts or a workout question. What do you think of when you hear aerosols? Because we're going to get to that really soon. This conversation is also being recorded and will be available on the NCAR Explorer series website. With us today, we have Howard University professor, Dr. Otsunashi Ajoku, and NCAR scientist, Dr. Rebecca Buchholz. Dr. Otsunashi Ajoku completed his PhD at the Scripps Institution of Oceanography in sunny San Diego in June of 2020. Shortly after, he started a postdoctoral position under the advanced study program at NCAR. Currently, he serves as an assistant professor with Howard University's program in atmospheric science. His research revolves around better understanding aerosol cloud radiation interactions over Africa and the adjacent Atlantic Ocean using satellite observations and regional and our global climate models. Dr. Rebecca Buchholz completed her PhD at the Center for Atmospheric Chemistry at the University of Wollongong in Australia, studying southern hemisphere atmospheric compositions, using a range of measurement and modeling techniques. In October of 2014, she started a postdoctoral position in the Moped Group with an NCAR and joined the team as a project scientist in 2017. Her current research uses global climate chemistry modeling and remote sensing to answer questions about air quality and atmospheric composition with a particular focus on the impact of wildfire emissions. Rebecca and OC, welcome. Can you turn your camera on and give a quick hello before we check out the workload? Hello, everyone. First and foremost, good morning, good afternoon, wherever you may be. And yeah, it's a pleasure to be here. I'm looking forward to this conversation. I'm Rebecca. I'm also looking forward to talking about weather and wildfires today. Okay. Thank you so much for being here and saying hello. Now, before I turn this over to our speakers and we get into our science, let's check out your thoughts on a workload. Paul and Brett, would you share a slide for us please? Let me see. Why do we hear? Yeah. So what comes to mind when we hear aerosols and we have spray cans, bat news, hairspray, which is what I was thinking about fog and smoke, particles in the air, set, small particles, clouds. What do you guys think about these answers from our audience? I think we have a very enlightened audience. And yeah, no, I'm very happy to see these responses. Very good to know that the audience is knowledgeable ahead of time of what we're going to be speaking about. Yeah, this is a really good range of responses for this question. We have the hairspray and spray cans as we all know and hear about aerosols every day, but we also have the definitions in there as well. This is great. I'm very proud of her audience. This is great. I really thought it was going to be all about hairspray because that's the first thing I have. But thank you so much for setting me straight that this is not the kind of aerosols we're talking about today. OC, one of your areas of research interest is a transatlantic transfer of aerosols, and one of Rebecca's is conducting atmospheric measurements. Could you guys tell me how your different areas of research intersect? Yeah. So when you think of, when I think of fires, right, let me be more precise when I think of fires and biomass burning in particular, it's not only just the release of aerosols into the atmosphere but you're also releasing quite a bit of gases. These gases are very responsible for air pollution. Some of these gases include carbon monoxide, nitrous oxides, and the reason to me why it's important to study some of the effect of these gases is because they're precursors to ozone. And we know that ozone can have tremendous impacts. And I think that's just one of the few different ways in which Rebecca and I research and intersects together. So let's talk about one of the tools that I use to study atmospheric chemistry is observations from space. So if we bring up that first image, we can see this is really observations of fires from space. So each one of these little red dots is a location of a fire. It's not the size of the fire, it's just a location so they're not huge fires. So this is a satellite image and it's observations from NASA. And that green circle there is the region of the world will really be focusing on today but we can see there are fires all around the globe. So fire is really a global phenomenon. This is August in 2018. So this is an observation of where the fires are. And I also use observations of atmospheric chemistry components like O.C. mentioned carbon monoxide is a gas. So I use a lot of satellite measurements of that particular trace gas. And there are also measurements of aerosols which we're talking a lot about today and so that's kind of where O.C. and I overlap in terms of the aerosols and then the interaction with weather in this particular region of the world. And just to add an extra fun fact for the audience. If you saw that slide you saw that Southern Africa was circled in green. And a fun fact is just that Africa is the single largest continental emitter biomass burning aerosols. So when you're talking about aerosol emissions or biomass burning aerosol emissions on the global scale. Africa is the largest source. I did not know that. Thank you so much for letting me know that. And for our audience, please make sure that you are answering our slide of questions. We have one coming up in which we're going to look at why would we study fire seasons, but Rebecca and O.C. with your roles and what you're doing right now. What was it that made you become interested in doing this type of work. So, yeah, actually this work is near and dear to me. So I'm actually Nigerian American. I've been home plenty of times and every time I went home, primarily during the winter season, you would always see smoke in the atmosphere. And it's very rare that you're actually able to see a clear sun or even the sun beaming hard on you. But nevertheless, it's still hot and there's plenty of air pollution laying around. You can see the smoke just in the horizon everywhere as far as I can see. So that's what's really started to pique my interest in this research. Yeah, and for me, I am really interested in understanding how things work. And I also have this interest in mathematics and chemistry. So atmospheric chemistry is like the perfect combination of mathematics and chemistry for me. And in terms of specifically looking at fires, I'm actually asthmatic. And so I noticed when I moved to Boulder in the fire season, my asthma would be starting to get really bad. And so understanding why that might be the case and where it's coming from is kind of got me interested in it. Well, you mentioned fires. So I want to bring up the slide a question as to why would scientists want to investigate fire seasons. Why would we care. And our answers are because of heat preparation, because knowing the conditions leading fires we can face this problem. And we're learning so much about how paracumulus drives further storms, and why there's some global temperature increase so might fires, and I am in Colorado and in Colorado we are very familiar with wildfires, but oh see that is not the same. What exactly does it mean to have a fire season and is her audience on the right track and what they're thinking. I would say more or less so they are correct. So when I think of the word season, I think of a portion of the year that's marked by particular weather patterns. And so when you think of the fire season, it's pretty much falls into the same category, every fire season is marked by particular weather patterns. So when you think of a fire season usually think of warm, dry conditions, not a lot of precipitation, but most importantly for fire season relative to a wildfire, you need to have a sufficient amount of a fuel source. And in this case the fuel source is vegetation, particularly grassland and Savannah types of vegetation types, and these usually act as the source for the burning so that's what I think of and I think in terms of fire season. And it's pretty prolonged. And in this case it might be on the order of a couple months. So to add on to that, when you, when you think of season right the word season as a climate scientist sparks the word predictability. So when you're able to understand what's actually causing the fire season, you're able to better understand how to predict it, you know ahead of time and that's pretty much the name of the game, being a climate scientist so it's very important to understand how the vegetation burns. So by understanding how the vegetation burns, you're able to understand the intensity of the admissions, which leads into another bag of worms. Right, and then I can keep going on and on but that's what I think of and I think of the term fire season. Where are these fire seasons the most common what do they happen. Most commonly. That's a really good question. So most commonly these wild fire seasons occur in the mid latitudes, usually in dry climate so when we think of our earths convection cells we think of the Hadley cell. The Hadley cell is the region between the tropics and desert regions, responsible for the convention of air so usually in the descending parts of that region in the mid latitude say near the Sahara desert, near Australia, you have these large high pressure systems, and these are large high pressure systems are partially responsible for the dry conditions that are occurring, particularly over the Saharan desert and over the Gobi desert. And when you have these dry conditions you just have dry air being blown around so this tends to evaporate some of the water that's in the soil reduces the soil moisture. And this essentially leads to the start of a fire season. Information can we gather from prior seasons like what do they tell us about what is happening. And are there any models that help us understand what is going on with them. Another good question so when I think of fires. I tend to think of human behavior. Kind of a weird comparison but just follow me. So most fires that are occurring throughout the planet they're actually anthropogenic and origin. So most regions where these fires are happening particularly places like Africa, they're driven by agricultural means. So, you know, if you're living in a rural region, particularly over Africa and places like Southeast Asia, your, your agricultural needs are there. They're relying on the fact that you're clearing the grass from the prior season before and that's a term known as slash and burning. So slash and burning is actually a large contributor of the fire season and the fire missions that we see in most of the world. And less so on the natural side will be a lightning strike so that's what fire seasons usually tell me this is, it tells me a lot about human behavior. Before I ask you another question let me see if our audience has any questions that are popping up through Slido. Any questions from our audience. See, okay. Okay, well then I have a question. As you have been researching this for a few few years like let's say you're an expert on this. Are we seeing any changes in fire seasons over time like how they're developing the size of them. Is there something different now. Okay, one thing that we've noticed is, is the onset and the length of the fire seasons. As we're evolving on the, on the changing, you know, planning with climate change we have to understand that nothing is set in stone as they used to be. So one thing that we're trying to understand is exactly the length of the fire season and this is usually. Usually changing depending on the location wherever you're at. So I know particularly over the western US, where springs are happening earlier, or the onset of spring is occurring earlier in the season. And that can have an impact on the fire season but from my perspective with the area that I look at it's kind of hard to quantify these trends, because you know, these fires are so variable in nature. I don't know, Rebecca, if you wanted to add on to that. Yeah, that's exactly I agree with that totally definitely there are these regions in the world that are being longer fire seasons due to hotter try conditions already, but it's not the same everywhere. Yeah. So it's a fire season for not the same everywhere. What are the particles are being emitted the same. Because when I think about fires and particles, I tend to think about ash and large materials, but Rebecca, those are not the only emissions from fires correct like, could you tell me more about what kinds of materials are generated by the fires. Are they solid, what is of matter our day. I think that's a really good question. Definitely there is a being emitted from fires we see it with our eyes. And that's not the whole story. There's more to the story than that. There are other particles and gases, it's actually a really complicated mixture of gases and particles that are emitted in the smoke and emitted from these fires. There's an image here that my colleague Kelly Bafanti showed a couple of weeks ago, and I thought it was a really nice image showing all the different types of aerosols that you might see coming out of a fire so we have these black carbon articles or aerosols, and you can absorb a little light and that's why they're this sort of really dark black color. And then over on the left it shows a little brown a color that's the brown carbon particles. And then we also have down the bottom in the white lighter colors organic carbon particles so there's lots of different complex particles that can be emitted, as well as these gases that we were talking about before carbon monoxide is one of those there are carbon containing complex molecules that can turn into particles later they're kind of sticky molecules that can coagulate together and become particles. So yeah it's really complicated. Yeah. So, you mentioned that we have brown carbon black carbon in particular, particularly organic matter. So, let's see that matches with whether audience said that particles are being emitted. Could you please bring up the slider question. The multiple choice. So, see our audience knew it and honestly they were better at this than I am, I really was thinking that all the particles that we could see coming out we're going to be very large and microscopic. But Rebecca, could you give me an idea of how big these particles are, or how small this particles are. Yeah, a lot of these aerosol particles are actually quite small if we go to the next slide. So, we have this definition of PM 2.5, which means the particles are smaller than 2.5 microns. And so we can see this in relation to a human hair here so this gray image in the middle this gray line and the image here is human hair zoomed in. And the little blue dots are PM 10 so those are particles that 10 microns or smaller. And then within those blue particles are these little PM 2.5 particles. So they're really really tiny if you look at your own air and you could imagine these really tiny particles. And a lot of that smoke is made up of this PM 2.5 particle size aerosol. And the reason we're really concerned about these PM 2.5 aerosol particles is they do have health impacts so when you breathe them in they're really difficult to get out of your lungs, and they can cause cardiovascular issues. So, how do we measure the amount of particles that we have and what are considered accepted levels of particles emitted for air produce. Yeah, so we tend to measure these particles there's lots of different ways of measuring that the units are micrograms per meter cube that we tend to use so it's kind of like a way to as these particles in the air. In general we want to have them pretty slow so we really want them to be kind of below 12 micrograms per meter cube. That's really healthy quality and when we have smoke events like we see in the West Coast of the US and you can see the smoke that's unhealthy that's really unhealthy levels and they can get up to above you know 150 micrograms per meter cube. You mentioned that they were getting into the Western area. How are these particles being transported in those distances like how are we getting them from all the way over there. Yeah so because these particles are really small there's 2.5 micrograms they tend to stay in the air a little bit longer than those particles so the ash can kind of fall out pretty quickly. But these tiny particles and aerosols can be lofted into the atmosphere a bit higher and at the higher altitudes there are stronger winds that can transport them far distances. But for example in Colorado we can see impacts from the West Coast fires that we have in Pacific Northwest in California. We got some pollution from those in the last few years here in Colorado and really bad air quality days due to the fires that were happening on the West Coast. So these particles are being emitted from fires. Are they affecting our weather properties are they doing something to our weather. Yeah there's a whole there's a whole bunch of interactions that aerosols can have with the climate and weather so we saw those different aerosol particles the different colors of them that the black carbon the brown carbon. So they have different direct interaction with sunlight. You know they may absorb less or more of the sunlight and so that can change the regional temperature. And then there's also scattering properties so instead of absorbing some light it can just reflect it away and so reflecting away can also change the local temperature as well. And then there are other aspects where the aerosols can interact with water and determine clouds how bright those clouds are how many clouds there are and and whether it might whether those clouds might create rain or not. So that's kind of an overview of all these interactions that aerosols can have with whether I'm not sure if I was to add anything else there that I might have missed. Yeah no you covered the gist of it I can. I can talk a little more but I think I might speak about that in a little bit. I am being told that we have a question from Steven so can you please bring this up. What is an aerosol that is taking it back to the basics of this. So an aerosol is just a particular matter suspended in the atmosphere. That's a bare basic definition of an aerosol and that's why it would include hairspray. Because when you spray out the bottle you see it floating in air. At that moment it's an aerosol, not when it's in the can. I could just add to that as well these little particles can be solid. They can be liquid or they can be a mixture of both as well. Oh C's most of your research has to do with biomass burning in sub Saharan Africa and I understand that you study a particular set of months for the months in season. Before we get into what your answer is I want to know what our audience think which during which months with scientists study months in the Gulf of Guinea. So may we please bring up that side of question. Oh, our audience is divided. We are all over the place so I'm OC. Could you please first start by saying when and why we study months with these windows particular months please. Yeah, so the answer to this question is actually the third option between the months of June through August. And I can actually elaborate on that portion a little bit. This actually deals with the prior question that you asked me dealing with the progression of the fire season. So, some over the continent of Africa the progression of the fire season is really dependent on the location of what we call it ITCZ, or inter tropical conversion zone. So by understanding that this ITCZ is bringing towards a moisture into the continent. This is responsible for the moisture associated with the monsoon. Since we said that a fire season is usually occurring when there are dry conditions available. We know that over Africa, and particularly West Africa, the fire season is not occurring with the monsoon, but as the ITCZ as it migrates further north and southern Africa, you have these prolonged dry conditions, which are very, which are very, you know, needed for these fire seasons to start so during the West African monsoon season what we call the WAM, which is occurring through the months of June through August. You also have the onset of the fire season in southern Africa, which is transporting aerosols over the transatlantic. But it's really fascinating. I could not pad them to understand like that idea of monsoon and fires both being correlated. So, oh, see you have been researching the monsoon season, as you said, with regards to fire season and biomass burning. What was it that made you interested into that research and what are its origins. Yeah. So as a student, I was one of those really nerdy students. I was just constantly watch satellite images, you know, the videos that are looped together, the hourly and the daily images, and my attention was always focused over Africa. And I would notice that okay, these fires are happening like clockwork during these specific months in southern Africa from June to October. I also noticed that okay, the ITCC is shifting north and we also have large cumulonimbus, you know, clouds in West Africa, large scale convection. And I always see these smoke aerosols being transported with the monsoon. So one cool thing to mention about the monsoon is that it's caused by not only the migration of the ITCC, but also will be called a large atmospheric temperature gradient. So going from the Gulf of Guinea towards the Sahara Desert, we have increasing temperatures. So when you reach the Sahara, we have very hot temperatures, and this causes air to converge in that location. And this is what we call the monsoon flow, right, which is also in the same location as a trade wind. So when these, when these fires are occurring, the smoke aerosols are being transported with this monsoon flow into the West African monsoon region. And that's what makes it a very interesting location, a study. That's really, really, really interesting. Could you talk to me a little bit about how aerosols influence light attenuation weather of how does that affect having all that smoke. I'm not sure if we can pull up slide six. Yes, so this is a picture of the light attenuation and I know Rebecca touched on it earlier. But just that everybody in the audience know it's it's a totally different beast when you're able to see this upfront in person, when you're actually on the ground under under a layer of smoke and you're actually seeing the attenuation. So, like Rebecca mentioned, these aerosols have various radiative and micro physical properties, and most of these biomass burning aerosols have an absorbing nature. And when you're absorbing radiation, a loft above you, you have less radiation reaching the ground. So just imagine if you're standing outside and you see a cloud pass by the sun. Less radiation is reaching you now in terms of the larger research that I'm interested in this monsoon region is affected by this temperature gradient, which also has a radiation gradient. So by influencing or reducing the amount of radiation over the Gulf of Guinea, you're actually influencing this temperature gradient as well. So, these aerosols have plenty of impacts but that's, you know, just speaking a little bit about the radiative properties. So, let me see if I understood this, what you're saying is that these aerosols are affecting how cloudy or how bright it is on the Gulf of Guinea, like, is that what you're saying. Yeah, correct. So, another fun fact for everyone in the audience, every single cloud you see in the atmosphere are composed of aerosols. There are no such thing as clouds without aerosols. I mean, it's possible, but it's, it's very hard to achieve naturally. So, understanding that we can understand or try to better understand the impacts that smoke aerosols have on cloud formations over this region. And this slide right here is an image of recent field campaigns that have been conducted over the Atlantic Ocean to understand these, what we call aerosol cloud radiation interactions. And just to name a couple of them, you see the Oracles campaign, as well as the Lasik and Clarify campaign. So these are campaigns that are originated out of South Tyome in the Gulf of Guinea, as well as Ascension Island, which is in the center of that red rectangle you see on the right hand side. So, plenty of these campaigns have been used to understand these aerosol cloud interactions. And in the area where you see the purple and the yellow right there, what we call Walvis Bay, adjacent to that you have a large stratocumulus deck. And stratocumulus clouds are very important for reflecting incoming radiation and maintaining that radiation budget over this region. So, to better understand how these aerosols influence these cloud formations can help us understand how the radiation budget over this region as well. Awesome. And I know you have touched upon this again, but I just want to make sure that I really understand this. Could you please talk to me a little bit more about that relationship between the monsoon season and wildfires again just a little bit more. So, during the monsoon season, and over the Gulf of Guinea, we have large cumulonimbus large large cumulonimbus clouds we have large scale convection. Now, in order for this convection to maintain itself, the atmosphere has to be what we call unstable, meaning that as you go higher in altitude and atmosphere temperature starts to cool down and get a little cooler. Now, if you introduce this smoke within the monsoon flow, and we understand that the radiative properties of the smoke is in an absorbing nature to absorb radiation, this tends to heat up the location that this smoke is residing. And we can understand exactly how the smoke aerosols are influencing the stability of the atmosphere or the ability for the atmosphere to convect or lift air that's on the surface higher up into the atmosphere where the air, you know, dissipates condenses creates a cloud and forms precipitation. So that's the direct connection between smoke in the monsoon that connection is really through the modification of the cloud structure within this region. I have also a clarifying question for myself, you mentioned radiation budget. What does that mean, what is a radiation budget. Yeah, so a radiation budget or a radiative balance is how the earth's basically keeps itself cool. So because the earth is tilted on this axis. We have excess radiation at the equator, and the earth is trying to move this energy towards the polar regions. And it just happens that where this monsoon region is occurring is near the equator, and this energy is being this excess energy that's accumulated in the equatorial regions is being transported towards the poles. And that's happening usually at the surface. So by understanding how aerosols can influence the amount of radiation reaching the ground, we can try to better understand the possible impacts that these aerosols may have on the earth's radiation budget. Yes. So we have a question from the audience. May we please bring up Jeremy's question. That's not it. It says observing from space are the effects of the biomass burning on light attenuation more important when the smoke is above below or within the clouds. First and foremost, Jeremy, this is a very great question. I think what Jeremy's touching on is essentially what we call the aerosol semi direct effect. So the direct effect like Rebecca mentioned is the direct interaction that aerosols have with radiation, but sometimes the aerosols not only do they absorb the radiation but they can impact a vertical temperature profile. Right. So to answer Jeremy's question, it really depends on the type of cloud and location that you're looking at. So just to stay, just to keep this in perspective with the region that we're talking about over to Southeast Atlantic, you have low level in this clouds and these clouds are usually somewhere between 500 to 1000 meters in altitude. Now sometimes you can have smoke residing let's say about 1500 meters in altitude. So this would put the smoke above the clouds. Now what that would do in some cases according to research and you know Jeremy, you know you can get in contact with me I can reference you later. This tends to thicken the clouds underneath what we call cloud thickening. So that's in the case where smoke resides above a cloud. If you have smoke residing within the cloud is can lead to cloud burn offs and that can have the opposite effect, where instead of thickening the clouds you can lead to cloud dissipation. So, yeah, and that was kind of a long answer but it really just depends. Thank you. We also have another question from Ariana. May we please bring it up. Oh, this one is fascinating. Modeling community is not totally agreed on how aerosols particularly from fires impact weather and climate prediction. What are your opinions on this. Yeah, no, I can go. So my opinion models vary in nature. Right. And every model is run with different dynamics. So that's why most models tend not to agree. I would say it's actually more important just to understand the fundamentals of what's going on in terms of the fires burning how these aerosols interact with the other components of the earth system. So my my understanding or my belief is to have models understand the questions that I can't answer using observations. Right. So for example, with the satellite we can only see straight down, right from the top down that's the top down profile. We can't really understand what's occurring. We can't understand what's occurring within the cloud structure. And that's what that's one of the many uses that a model can help us to understand. Before we move on to our next topic, I just want to see what our audience is thinking about in a slide or Paul, what effects could biomass burning have on our climate. I am very interested to see what they think about it. Whoa. Yeah, changes in precipitation. Yeah, changes in clouds, more lightning, Newton cycle changes. Rebecca, what do you think about our audiences answers on this question. Yeah, these are great. These are great answers. It's it's basically all of all of them. Yeah, there as we've been hearing today already, fire is really an integral part of the earth system. And it has all of these potential impacts in terms of when it emits smoke and how that smoke might interact with the climate. And so yeah, changes in clouds might happen as both the OC was just mentioning how it can how it can dissipate the clouds depending on where those aerosols from the smoke are located above or within or and what type of aerosols they are whether they're those absorbing strongly absorbing or reflecting aerosols. And then, yeah, the changes in precipitation as well as we were mentioning, depending on the interaction with the cloud as well. And then the regional temperature changes and this is all really important for the Gulf of Guinea and Sub-Saharan Africa area that OC and I are interested in studying. And then there was that point about more lightning as well for we have in really strong fire situations really strong smoke plumes we have intense energy being released and lots of aerosols and we can actually have these pyrochemical and combust clouds which create their own weather and lightning and that can also be impacted and then in terms of lightning, it's aerosols seem to be needed in the earth system to create lightning. So when we have more aerosols from smoke that that impacts lightning as well. So yeah there's definitely many reasons to think about biomass burning and how it can impact and influence and interact with the climate system and weather. So that is why scientists are very interested in biomass burning but me as a person. Why should I be involved in understanding the effects of biomass burning how does it affect me right now. Yeah, I mean we've seen some really intense fire seasons recently in the North America region. And so fires can have really direct impacts on people locally in terms of health and property and and local impacts. And there's also these transported impacts in terms of health where the smoke is transported downwind. As someone who might live in places affected by this smoke, it's important to think about how we might want to reduce these extreme fire events that are occurring. I like knowing. I always like knowing the science but I also like knowing why besides the science so it's always fascinating to me. Yeah, so I was wondering, because I hear a lot about El Niño, El Aniño and all of those things. Are any of those like climatological phenomenon affected by biomass burning. Is there anything that they do. Yeah, it's really interesting because so the climate system is really interconnected so we have the climate impacting fires. We have you know, depending on the El Niño southern oscillation which is a measure of climate variability based in the Pacific Ocean. That climate variability can impact fire variability depending on how it impacts different regions, whether it's drier or warmer. It can influence whether fires occur. And what we're finding as well is some of these huge fire systems like the ones we saw in Australia in 2019 and 2020. They can release so much smoke and pollution that they can actually feed back into the climate system and start to potentially alter these large climate variability signals that we're seeing. And so there's this this really complicated back and forth between the climate impacting fires and the fires impacting climate. And one of the things that is also happening that OC talked a little bit about is that we now have places that are burning that usually didn't burn. Could you talk to me and well us a little bit more about why that is happening. Again, it's this kind of changing climate impact on different regions so one of the particular locations is the permafrost in in northern hemisphere areas. So we could bring up the slide nine actually. There's a really good image on the left of slide nine that shows this kind of legacy carbon this carbon that has been stored in the earth that which is usually covered in water and is really difficult to burn as it dries out this carbon that hasn't been in really for a long time starts to get burnt and so this image on the left is this artist's impression of what's happening is fire is attached attaching itself to this legacy carbon in in the permafrost that hasn't burned in a long time and releasing carbon dioxide and aerosols and emissions that we usually stored in the earth. And then on the right here we see one of these recent fire impacts in North America, our close it is to human populations. Oh, see, I'm going to bring this back to like our backyard in the US. So, could you please, once again just like try to explain to me fire seasons just to make sure that we have fire seasons very very very straight. So, earlier on I was saying, a season is just a prolonged period with particular peculiar weather patterns and in this case over the US. We can see that the fire season usually occurs in the middle of summer, leading into the fall. And you can see looking at the legend you can see how this is differentiated between us as a whole in the western US. So, over the western US during the summertime, we are exposed to prolonged periods of dry conditions. And to add on to what Rebecca was saying, particularly in like a lot mean year where we have drier than normal conditions because we didn't get enough precipitation from the prior winter. This can actually exacerbate the fire season and increases intensity. And that's essentially what we're seeing here. The, we're seeing fire seasons by looking at one of its proxies which are carbon monoxide emissions. And yeah, so that's what we understand so over the US we understand it's mainly happening in the West Coast. Other areas that are also experiencing fires particularly areas that are covered with a low level forest such as northern Michigan, and we also have a pretty quantifiable amount of biomass burning occurring in the southeastern US. I believe that's the burning of old sugar cane, sugar cane crops, you know that's also a form of slashing burning. So yes, prime time to do it right before the next planning season. Thank you so much. We have a very interested audience. So we have lots of questions. So I hope you're ready. Okay, let's just get started here. We have a question from Mike, which is how does climate change impact fires, and how fires impact climate change. Yeah, I can, I can start off with that if you don't mind. Yeah, so I'm going to do something different. I'm going to talk about this more from a social perspective, you know from a human point of view, not just thinking of the earth as you know just a system by living on its own. But we, it's good to understand or try to thoroughly, you know, get your head that we're partially at least fully responsible for climate change right the anthropogenic impact on climate change is real. Right. So, by understanding that climate change industrialization right can help influence you know fires you know activities such as deforestation right can influence fires and that's really where I'm getting at in terms of how we can actually impact you know how climate change impacts fires and how fires can impact climate change. So when you have more fires and more emissions you have more issues with air pollution as well. When you have more fires you also have changes and temperatures right regionally and also could be in another part of the globe. So, in Africa where I'm looking at I'm actually looking at how southern hemisphere biomass burning aerosols influence northern hemisphere precipitation. So, that's a good way. I think that we can understand that. Thank you. In our last 10 minutes let's see how many more questions we can get to. May you please bring up the questions. Oh, from Catherine. I think Rebecca mentioned this what are the alternatives to slash and burning. I actually, I really can't think of any alternatives. Right. Just once again going to a human perspective slash and burning has been a process that's been done for thousands of years right definitely before we were around. So, it's really hard to find an alternative. I think it's more so finding cleaner ways to burn. Yeah, that's that's a really tough question. And that's something that researchers I think are still trying to study and quantify until today. That is a tough question. I was just going to add something that I have heard about people using goats to manage to manage landscapes in terms of reducing vegetation. So, I'm not sure if that could potentially be a way to manage, manage crop residue, but, but that's a way that there's actually management of wildland systems using boats to keep down the weeds and the underbrush. We have a question from Mary Ann, which is, are dirt important aerosol differences between forest fires and grassland fires. Yeah, that's a really good question. I think I'm not sure if he was just about to say something and I think there are differences in the aerosols and emitted gases that you see from these different landscapes or vegetation types. And that's definitely something we use in our model that we have different emission ratios for different gases and aerosols when we when we model the emissions that are coming out of these fires. Yeah, you're definitely right. So depending and you know I'm definitely not a botanist so I can't answer this with, you know, thorough certainty but the ratio of black carbon to brown carbon usually is different depending on what's being burned. In addition, when you have forest fires you also have an increased emission of ice supreme and other volatile organic compounds. Maybe that's a another something else that the audience can look up on their own volatile organic compounds VOCs. These are usually emitted more in forest fires, I believe. Right. Okay. Oh, from Jacqueline. How will modeling the transfer of wildfires aerosols across regional to global scales be addressed in atmospheric chemistry models in the future. Yeah, I didn't want to do this but I guess I guess I'll plug myself in a little bit. So to answer that question, which is another man, he has some heavy questions. Oh man I'm kind of sweating here but anyway. So I'm looking at how these black carbon or brown carbon aerosols are aerosols from biomass burning. I'm looking at how these aerosols impact something called a cloud transition over this region. Over the region I was looking at in the Atlantic Ocean we have the stratocumulus clouds that I mentioned, but we also have cumulus clouds. And this just occurs because you know when you're going from some tropical waters into tropical waters that the sea surface temperature starts to increase, and the clouds change just to keep it simple. So I want to understand how those clouds change in the presence of biomass burning aerosols and that's definitely something that we can answer using atmospheric chemistry models. Great. I, let's see what we have here. Let's look at Sam's questions, Sam's questions. His PhD research was on assessments of extreme climate change related hazards. From his research, he observed forest fires occurred on some highland forests. He tried to extract the historical dates of occurrences from fire data. But the spatial resolution was coarse. Are there any websites that are archiving forest fire data for researchers to work on and can we have an NCAR research working group on extreme events. He's interested. I can definitely answer the former question. Well, you're definitely right Sam in the sense that a lot of these measurements are pretty coarse. So it gets, it gets hard to quantify an original or even a larger scale, exactly what's occurring but one website that may be helpful and I don't know if Rebecca you're going to mention this website as aeronet. So aeronet AERO and ET aeronet that is a site that's a, it's pretty much ran by NASA and various PIs affiliated with NASA and aeronet is a station of instrumentation that's located in different locations. The measurements used ground based lidar to observe various meteorological variables including aerosol concentrations or what we call aerosol optical depth. And from this you might be able to answer better questions and I know that the aeronet density is pretty good, particularly over the US but also has a worldwide, a worldwide existence so you'll find these aeronet sites throughout the globe. Yeah, I would just add, you could look at, I'm not sure at the time period Samuel that you're looking at but there is the fears the light instrument as well but has higher resolution measurements of fires and you could also look at trace gases that might be coming from for example from aldehyde is measured by Omi and tropomy and comes from other sources as well but that might be an indicator of fires if you look at different trace gases that are signatures from fires. And then an NCAR working group on extreme events that sounds very interesting we should, we should consider that. Great. From Mary Ann, I have read that aerosols injected into the stratosphere can circle the glove in a matter of weeks. Have you heard that and is that true. Yes, true. Rebecca, did you want to add on more to that. I was just going to say that Australian wildfire season 2019 2020 was a huge example of that it got into the stratosphere it circled really quickly and then it stayed there for a really long time. Great, we have two more questions. What are some of the chemical differences between brown carbon and black carbon from Finn. I can start off on this and maybe oh so you can add if you have anything to add that the black carbon is really those solid particles it tends to be that kind of really fine solid ash like particles that are that are small that the brown carbon is more organic molecules that are sticky and and more liquid in nature and so there are lots of different types of organic molecules that go into a brown carbon particle. Yeah, more or less. Yeah, I would agree. Last question from our audience. cultural burns are used in many places of the world to sustainably manage fire prone landscapes do either of you know that has been done in Africa as well. Yeah, that so good question. So KP that's exactly what I meant earlier when I talked about agricultural practices, and how you know fires really tell us a lot about human behavior so the same thing is really over Africa most of these fires that we see are a product of slash and burning, although, you know, a good portion of it is due to deforestation, which is for different political means we can talk about another day. So, for any students who are listening today, what advice will the two of you give them if they're interested in becoming a scientist like the two of you. I'll go first. Number one thing is to have confidence in yourself. You know you might hear like the typical go to answers of, you need to make sure your grades are great you know we need to have all of these skills but the number one thing that I'll say and I'll let Rebecca touch on some other things is that you need to have confidence in yourself. I think adding to that to gain that confidence is to really follow areas that you enjoy studying. So there are lots of different ways to get into science and so you might be interested in data analysis and really understanding what the data is doing. So what you might be interested in statistics, there's a new field of machine learning and AI that can really have really interesting applications in atmospheric chemistry and atmospheric science. Or you might really be interested in visualisation and so creating beautiful plots or beautiful maps like we saw today that's something that is really important in science or communicating science as well like for example journalism about. There's many different ways to be involved in science and so getting that confidence in the direction or the subject area that you really like and then bringing science into it I think is a way to to really gain that confidence. Thank you so much and with that Rebecca and OC thank you so so much for being here today to chat with us about wildfires and the really cool and amazing work you're doing. Also, thank you so much to our team behind the scenes Paul, Brad, Aliyah and Dan for supporting this conversation. If you're interested in more NCAR Explorer series events, definitely check out our website for upcoming lectures and conversations, as well as to see recordings of past events. So I hope to see y'all next time and have a great rest of your day. Thank you so much.