 Hi everybody. Thank you for joining us for our Explore Series Talk this evening. I hope you're doing well from wherever you're joining in from. My name is Lorena Medina Luna and I am an education and outreach specialist at NCAR or the National Center for Atmospheric Research. We're not familiar with NCAR. It's located in Boulder, Colorado, but today we're coming to you live from our own homes. And thank you for welcoming in us into your own spaces as well. NCAR is a world leading organization dedicated to the study of the atmosphere, the earth system and the sun. We're excited that you have decided to take some time to join us today. We have a very interesting lecture about the upper atmosphere and the ionosphere titled Space Storms in the upper atmosphere and the atmosphere with Dr. Stan Solomon. Throughout this event, you'll be able to ask questions and engage with us through interactive polls using the Slido interface. So if you go down the page, if you haven't already done so you can go into Slido by clicking on the link and you'll see that we have some active polls and a word cloud that you can participate in. The event will be archived in our NCAR Explorer series website. So definitely check it out, check out other lectures that we've hosted in different conversations and events and let your friends know about this lecture. It should be posted up in a couple of weeks. And thank you for our multimedia services, Dan and Aliyah, Brett and Paul who are helping us with this program tonight. Dan, would you be able to share with us what is the word cloud looking like for people who are participating in what is something you think of when you hear the word aurora borealis? Have the northern lights, beautiful, nature's wonder, fantastic, only north. Beautiful self polls. That's a good question. You have the different lights that show up. The light show looks like curtains. Definitely welcome to continue entering your words on our word cloud. Thank you, Dan. And today I'd like to introduce you to our NCAR scientists, Dr. Stan Solomon. He is a professor of physics in the high altitude observatory laboratory and his research specializes on the physics and chemistry of the upper atmosphere and ionosphere. He received his AB from Harvard College and his master's and PhD from the University of Michigan, go blue. And throughout his career, Stan has researched the ways to analyze satellite measurements of aurora modeling of aurora physics and the upper atmosphere. He was the deputy director of the high altitude observatory from 2005 to 2009 served as the acting director from October 2009 through June 2010, and he now leads the geospaced frontiers section. He is currently on the upper atmosphere model development, working on upper atmosphere model development, excuse me, and the effects of solar geomagnetic variability and air glow simulations for the global scale observations of the limb and disc or gold, as it's known, mission. With that, I'll hand it over to you, Stan, to show us a little bit about the research that you do, and we'll come back and answer questions at the end of the event. So throughout the event, welcome to ask us questions, but we'll hold off on answering those questions until the end Q&A session. Dan, we'll hand it over to Stan now. Thank you. Good evening everybody. I'm going to start here by sharing my screen so you can see my slides and hopefully still see me. Yes, we can still see you and the slides show up well. Good. So, I'm going to discuss space weather. Meaning storms and also quiet periods that occur in the upper atmosphere and ionosphere of the earth. And when we use this term space weather, it's really an analogy. The storms in this very extended region of the earth's atmosphere are very different. They're not exactly the same thing as tropoceric storms. They're variability, sometimes dynamical variability, sometimes chromatic variability that occurs in the system. And so we have given this field that name in order to make it a little more accessible. And, but it is, in a way, a branch of meteorology is very different because you have electromagatism involved. And at the same time, you don't have some of the complicating factors of the lower atmosphere like water, for instance. So I'm going to talk about the main source, not the only source, but the main source of space weather, which is variability in the sun and the solar wind. Say a few words about the magnetosphere, ionosphere interactions. I hope I don't have to introduce some of these terms. This is the extended region around near earth space. It's controlled by the Earth's magnetic field. Say a few words about the impacts of some of these variability, why we might care about things that occur in space weather. We have an overview of the thermosphere and ionosphere system, really the atmosphere or ionosphere system because the thermosphere is part of the atmosphere. It's the, it's the very upper part of the Earth's atmosphere. And then talk about aurora, auroral forms, the, the, the global electric circuit, how that leads to these geospace storms that occur in the magnetosphere ionosphere system. And, but large to a great extent lot manifest themselves in the ionosphere. So, I'm going to start by showing this, this, this photograph or, or set of super pose photographs, just because I like it so much. It's fairly recent. This is a image by Milov Slav Duke Miller. This is taken during the great American eclipse of 2017. And by use of, of, of multiple images and image enhancement and some very, some very sophisticated techniques, he has managed to really bring out the features in the, in the solar corona that, that tell you the great extent of which corona is controlled by solar magnetism. Magnetism is going to be a constant theme of this talk. You can visualize through the illumination of these field lines, the, the morphology of the solar magnetic field, as if there were a bar magnet inside of it. And, and then you can see all this structure. Due to departures of that magnetic field from just a plain magnetic field or one that's controlled by active regions on the, on the sun. The corona and the magnetic field that's embedded within it stretches far out in the space. In fact, you can consider the corona of the sun as, as you can consider the earth as being inside the corona of the sun even because the solar wind constantly outflowing carries electrons from the sun all electrons and protons. And in fact, other ions, all the way to earth, and the variability in all of those particles and fields are ultimately what's driving most of, of, of, of variability in the thermosphere system. Not all of it some of it is coming actually from the atmosphere below from, from the, from the troposphere and ground atmosphere interactions. But those changes are somewhat less dramatic and we don't, we won't be able to get to that aspect of space weather today. So, when we think of solar magnetism, we speak of active regions, which are places where the magnetic field is distorted, concentrated into into local you might even call them hotspots. And these are associated with sunspots. They're, they're not quite the same thing as sunspots but they're different manifestations of the same process, which is variability in the solar magnetic field. So, in, in order to understand how variable that is, you can look at a longer term record of solar magnetism has manifested in this case by the sunspots before we had ultraviolet images this is a, this is an image in the ultraviolet. You can't couldn't see this in the plane visible light of the sun, but by, by normal visible wavelength techniques you can track sunspots and track for for centuries really, and give us a record of how variable the sun is. There's a approximately 11 year periodicity to that variability. That's still not fully understood why that should be that the solar activity should be so regular. And it's in the timing of its variability, and yet so different, both with regard to the active times and the quiet times. And also, each active time is different in intensity and we now understand that the quiet at times, as well, are not all the same it's not as if the sun constantly returns to its same state. So this, this plots about a cycle old. And the last cycle since 2012 or so. I mean, 2010 or so. It's been a very modest cycle of just come to an end and the next solar cycle is is now picking up and hopefully we'll get some addressing variability out of that. It's a phenomenon that will drive terrestrial phenomena, hopefully not too interesting. You don't want any catastrophic. Here's the same type of representation but in a very different way. In recent years we're able to track the solar cycle x rays and extreme ultraviolet. This is in x rays from essentially one cycle from maximum down to minimum impact up to maximum. These are one image per year basically it's representative of year. And you can see that as we get down to solar minimum, all of this interesting structure dies away. There aren't still events going on in the sun that are manifesting themselves at Earth, the upper atmosphere and I honestly are the earth, but it's much less dramatic. Obviously when something big, this goes off x rays. Now, when we see events on the sun, we people often speak of solar flares and one thing you may have heard is that is a Aurora Aurora phenomenon space weather. Changes in the ionosphere that this is all driven by solar flares. That's that's that's half true. Solar flares do impact the the outer regions of the earth atmosphere and I honestly are. But they're really just the the photon manifestation of that phenomenon. And of course, because their photons they get to earth very rapidly, they do cause ionization and so forth, a produce their own electromagnetic radiation over all wavelengths and can be very dramatic but they don't carry as much energy as the coronal mass ejections to which they are closely related you can say they're different manifestations of the same solar process. I want to run this one this is a image image sequence from a NASA satellite of a solar flare. Sorry. There it goes. And you can see all of this hot plasma, meaning mixture of electrons and protons and maybe heavy ions. They're just shooting out from the sun, and then then they're both emitting in the very short wavelength the energetic x rays and ultraviolet, and also, they're scattering solar light sunlight off of the electrons that are that are carried near the sun. Here's one of those coronal mass ejections. And it means that you actually have energetic particles that are still very small light particles, a low in density but much higher than the than the solar flares. And in terms in terms of their total energy. There's one here. Look at this area here. You'll see it's shooting off to the right. And when one of those impacts here. See it's two and actually one up here, one down here one up here. When one of those impacts the earth and of course in this case they're mostly going off to the side. But when you get one coming right at you. This is when you have the most dramatic consequences for the, the extended atmosphere ionosphere and magnitude sphere system. So that's illustrated by this NASA sort of cartoon representation of space with the processes. This is what happens when I see me comes right at you. If you could see that you would see a explosion of light. And then it goes towards the earth, and then trained in the solar wind. That impacts the magnetic field of the earth, causing events to occur in the tail of the magnitude sphere, the so-called magnetotail and energization to occur that interacts ultimately with the earth. Well it went by very fast so let me see if I can, if I can catch a few highlights here. This is what the magnetosphere of the earth roughly looks like if you could see the field lines that define the morphology of the magnitude sphere. It starts as a regular magnetic field, a dipole shaped magnetic field. But because it's embedded in the solar wind, it gets stretched out in this long magnetotail region. And then at the front end, you form a shock wave, because the solar wind, consisting of electrons and protons flowing rapidly out from the sun, more rapidly during one of these big injections but it's there all the time. And it's supersonic. And this, again this is by analogy with with hydrodynamic processes, just as we can speak of the hydrodynamic flow with something moving within the atmosphere, or for that matter the ocean. If it's moving faster than the wave propagations we even speak of that as supersonic or hypersonic. And the solar wind is the same way except the waves that we're speaking of are waves within the magnetized plasma. And so it's, and since there's a mathematical analogy between between magnetized plasma motions and hydrodynamics, the atmospheric or fluid motions, we pursue that analogy by saying well that's a shock wave. And then what happens in the magnetotail of the earth is you get recon, reconnection between these magnetic field lines which normally just send it out into the tail. And this energizes plasma and causes it to slow down the field lines where those field lines connect to the polar regions of the earth. And ultimately, you get emissions of light coming from the particles impact in the upper atmosphere occur in the vicinity of the magnetic poles of the earth. So that is all a lot to take in from the simple cartoon, but it's a nice illustration here's a more of a schematic. Again, it's it's it's simplified sort of imaginary diagram of the structure of the magnetosphere as it connects to the earth's ionosphere and upper atmosphere. You have the solar wind coming in because it's supersonic you get a bow shot. This is you wouldn't try to check supersonic jet plane. This tends to deflect the solar plasma. In this sense, the magnetic field of the earth. Think of it as almost protecting us from the from changes in dramatic changes in the solar environment. But at the same time, this this structure where the these magnetic field here near the poles connects way down to the to the extended tail of the magnetosphere. The currents that occur in the magnetotail map themselves into the into the polar regions the earth's ionosphere and causes disruptions of the electric field within its ionosphere and extend over the entire glow. I'll show sort of schematics or or illustrations of this a couple of times. It's not it's not a simple process, but this is the big picture of where the of how the sun and the solar wind are interacting with the earth's magnetosphere so the idea that the sun is driving these things, but indirectly, their effects, although they exist or smaller, and the solar wind effects are can be dramatic but they're there, they're modulated or or translated by the earth's magnetosphere. Here's a model of that process. The colors are the density of of electrons flowing in from the solar wind. And this is a little compass here indicating which direction the solar magnetic field is. I mentioned before that the magnetic field, which is embedded in the corona spreads out through the entire solar system, not just near near the sun. So we're so we're embedded in both our own magnetic field and the solar magnetic field, which is sometimes referred to the high enough interplanetary magnetic field. And the connection between those two things is what causes a lot of the dynamics of of the magnetosphere that imprints and stuff imprints itself to the ionosphere atmosphere system. See that will shock front moving across as as a solar coronal mass ejection impacted the magnetosphere. Electrons and protons electrons are doing most of the work here that are energized in the magnetosphere, then flow along a few magnetic field lines. This this little representation here shows that they're actually spiraling along the field lines shows another representation of that they're constrained to move by the by the electromagnetic forces constrained them to constantly move back towards their field line. So if they have a sub motion, a particular direction, they're attempting to go in that direction but they're constantly connected field line, because the, the, they feel the electromagnetic force. So that then as they flow into the upper atmosphere and ionosphere the earth, very high altitude. They collide with things. And this, when they collide with things, they excite them and they dissociate them and especially they ionize them. When they, the excitation processes and some of the dissociation processes, cause them the the atoms of molecules in the earth's atmosphere to emit light, ie, the aurora and the ionization processes contribute to the density the ionosphere and causes additional elect changes to the, the ionosphere electric circuit, which causes a lot of space weather. And you can always imagine that you know, you look at this picture of the aurora is, is, here's, here's currents flowing down into the earth's ionosphere from the manuscript, but they're also flowing along these currents that are caused by the enhanced ionization. So, just say a few words about why I care about these things. We'd like to say, well, that we are living in a technological society and space weather affects us all. Now, most of the important systems have, have ways to mitigate changes in the, in the ionosphere and changes in the magnetic field structure near the earth. Near earth geostases we call it. But you can still cause disruptions in navigation systems such as GPS satellite operations, meaning both, both technical things that happen when, when particles hit satellites, but also navigation in, in near earth space. A few words about that in just a second. Human spaceflight, of course, because humans are vulnerable to radiation of several different types. Communications especially most of these effects have to do with passing radio waves through the ionosphere bouncing radio waves off the ionosphere. And, and so consequently, large scale and micro scale, all scales really of perturbations in the ionosphere can affect radio communications or other uses to which radio waves are such as GPS navigation. Aircraft operations, same thing. Navigation is of course a concern, and any kind of radio blackouts or polar disruptions are of concern to who to transportation, because aircraft don't like to be out of touch with their with ground power grid operations is a little different. The perturbations in the, in the electromagnetism near the earth surface are very small, but when you have a very, very long antenna. You can concentrate fluctuation small fluctuations and, and long power lines can serve as such antennas, consequently, power transformers can be. Can be vulnerable to space weather events. Most of those are impacted through design. When your power goes out, usually look to a to a windstorm or hail storm or something. You know, the first thing you think of isn't usually that a space weather event has knocked out your power. It's, it's, it has been known to happen has to, it has to be guarded against and for, for, for reasons that are still obscure to me. It's a demonstrable fact that the spot, the spot market for power cost, which is very dynamic moves moves on very short timescales does respond to geomagnetic indisease, whether by the law of expectations or, or, or superstition. I don't want to say why but it's been demonstrated that people who care about power grids care about space weather. So let me say something about satellite operations on near Earth space is getting very full. Even even a little farther from the earth. This is a, this is a graphic where every point, every spot on this on this graphic represents a satellite, or a piece of something in space, most of it. Most of it is is debris. Most of it is so called space junk. Remnants of other satellites, things that flew off of satellites when they blew up for one reason or another, or collided with something else, causing an explosion. And, and as, as we populate space, especially close to the surface closer to the surface of the earth. More stuff we cause more debris and, and, and more risk of collision. And so this somebody put together this animation for NASA. I think it's sort of spectacular. This outer belt here, this is the geo stationary belt this is where the communications satellites TV stations are so forth, because they have the property that they're over stationary point on Earth. If you rotate and come in from the side, you can see that belt. And then there's many objects in sort of middle earth orbit, where still it's not terribly highly populated but as you come in to near Earth space. There's an incredible density of objects. Of course it doesn't. It's still, it's not as bad as it looks on this plot, because each dot is much bigger than that satellite to scale. But, but the risk of collision in close here is getting high and growing. Now, a much lower altitude you have a gap because once things get low, they encounter the atmosphere much more rapidly. And, or it was decaying the satellites burn up. Down to about three or 400 kilometers you have a belt, a very high density of functioning satellites, a lot of these are functioning satellites, most of it is just debris. And then constantly the functioning satellites are not are are not in for all of the prospects of having to fly through this different greenfield constantly and now there is a prospect of dramatically increasing the population of these near earth orbiting objects. And so commercial communications operations. And so, so the changes in those orbits, which occurs when they encounter the neutral atmosphere, even a very high altitude. Now, way out here to your stationary there's not enough atmosphere to change the orbit. In close here as the atmosphere of the Earth's changing the orbits of our functioning satellites change as well as the space debris, and all of it has to be trapped. There's often little you can do about avoiding a collision, but it's, it's nice to know about near misses, which are becoming quite common. So one of the rationale for trying to understand not just the ionosphere, the neutral part of the earth's upper atmosphere. In which the ionosphere is embedded. That's one of the rational for wanting to understand the other rationale being to understand. Another rationale brings understanding itself. So I mentioned that the ionosphere is embedded in the fantasy. Factoid takeaway. Before the take from this overview was very, very high level over you. It would be that the ionosphere, you know, it's largely referred to as the ionosphere because it was discovered early on. Through its ability to reflect and refract radio waves. It's still mostly neutral. It exists in the extended atmosphere of the earth to find the atmosphere of the earth by by its temperature gradient purpose here. Negative temperature gradient can colder go up and out to stratosphere as a positive temperature gradient, primarily due to eating from ozone absorption of sunlight by ozone. It's down again, but you open up to in this mess of sphere region, which has its own peculiar weather. And then we're getting to the form of sphere, not only does it dramatically heat, but there's a big difference between solar minimum and maximum reason for that is that this is a reason that's absorbing all of that extreme ultraviolet radiation in the sun and x-rays. And in that region of the sun spectrum is very variable. Also causes ionization ionization happens with large cross sections of highly probable compared to some of the processes that happened lower down. And even though the density is very low out here in the thermosphere, it's still quite likely that a solar photon of the extreme ultraviolet hit something. And what it does, it ionizes it. Here is a plot, the same region of density. Note we're going over 12 orders of magnitude on a logarithmic scale. And I'll tell you two things that atmosphere is dropping off in density exponential fashion. Straight line on a log plot. That helps explain it to you. And it's dropping off very rapidly. 200 kilometers is a fundamental difference between what I would say a fundamental change that occurs at around 100 kilometers. That must have changes from fully mixed to diffusively separate. What that means is, is that down here where we live is enough turbulence that, that, that everything gets mixed up and the castes don't care how much they're going to follow this drop off. This, this exponential logarithmic drop off all about the same rate so into molecular nitrogen, O2 atomic molecular oxygen, and other gases that if they're not chemically active like say Ozone, they are all mixed up and they have parallel lines on this logarithmic plot, meaning that their ratios are fairly constant. You get to 100 kilometers couple of things change one is that all the O2 starts turning into, oh, that is the molecular oxygen starts running into atomic oxygen, because it's being impacted by those photons, there's energetic photons for the sun, it's getting ionized, broken apart. And the other thing that happens is that because the molecular diffusion now takes over as a main process and that depends on how much the individual gas weighs, or what is masses. And so what happens is, the lighter stuff, like atomic oxygen, starts, starts following its own scale height, that is to say, it, it diffuses upward into space more rapidly, and drops off more slowly. Whereas the heavier stuff like say molecular nitrogen, or especially molecular oxygen drops off much more rapidly. So when you get up into the ionosphere here, we'll get to that in a minute. But as you get into the upper thermosphere, the atomic oxygen takes over and eventually the upper atmosphere, the upper part of the thermosphere becomes predominantly atomic oxygen, whereas down here where we are, it was predominantly molecular nitrogen, unfortunately for us, a little bit of molecular oxygen. So into that atmosphere we pour all of this electromagnetic radiation, so sunlight. Down here, the peak of the black body spectrum of the sunlight, around 500 nanometers, this is a visible region, and consequently I've colored it yellow. It's not very variable. Down here is I've put a high solar activity spectrum in red behind the yellow, the low solar activity spectrum in yellow, so the variability appears as this red fringe. And so in the ultraviolet, you can see there's a very small amount of variability. When you get into the extreme ultraviolet, this is the part that causes ionization. You get a lot of variability, a factor of two, between solar minimum and solar maximum, and that becomes as much as an order of magnitude in the X-ray region. That explains why the thermosphere, temperatures and densities, vary so much with solar activity. They are being controlled by this very shortwave extreme ultraviolet and X-ray radiation that is depositing its energy way up high here, around 100 to 200 kilometers, and higher. Whereas the less variable, regular ultraviolet is coming down here. This is not so much ionizing as dissociating parts of the middle atmosphere, and down here, it's being absorbed by ozone, which causes stratospheric heating. And then we get from the ultraviolet to the visible region, it reaches all the way to the ground. But by the time we get out here, the solar variability is very small, less than a tenth of a percent. So, not only does that cause the temperature of the thermosphere to vary dramatically, it causes the density of the ionosphere to vary dramatically because the ionosphere is being made by the absorption of all of that extreme ultraviolet radiation. And so, at solar maximum, we have an ionosphere that peaks up here around 300 kilometers. It's much more dense, as they say, there's more ions and electrons than at solar minimum. Now, as you go from day to night, you also have a big change. And that's because the ions up here, primarily O plus atomic oxygen ion, are fairly long lived, more than a day, but they don't last forever. So, once the sun goes down at nighttime, they largely diminish their density as they diffuse back down into the lower ionosphere, and as they recombine. In the lower ionosphere, the change is much smaller between solar max and solar min, but it's much larger from day to night. Because here in the lower ionosphere, you have a lot of molecules, a lot of stuff to react with, a lot of more density, and the lifetime of the ions is much smaller. So, once the sun goes down, they largely go away and the ionosphere becomes dominated by the so-called F region at high altitude. The F region may look like a conventional Chapman function, but it's really not. It's a balance between the diffusive properties of the ions and the recombination that occurs at lower altitude. And this code, DEF, this dates back to the dawn of the discovery of the ionosphere. The E region was discovered first and named the electrical region, and then, well, what's above the E region turns out there's a lot of ionosphere above the E region, what are you going to call it? The F region. And so, you will, because this region is so important to ionosphere electrodynamics, often we just refer to it as the ionosphere and say, oh yes, this is the ionosphere around 300 kilometers. But even though there's a lot of ions up here, a million per cubic centimeter at its peak, and more, they're not nearly as numerous as the neutrals. Neutrals still control what's going on to a great degree. The ions have a lot more energy and a lot more motion, but there's a lot more neutrals, a thousand times more neutrals, even here at the peak of the ionosphere. And then of course it only gets more neutral as you go lower, the ions get lower and the neutrals get higher. So that's why we really refer to thermosphere ionosphere system or the thermosphere ionosphere as a region. It's still predominantly as a thermosphere, but that's not a term that is as familiar to most people as the ionosphere. And here again is a region region is a little, a little bump here at the Eugene. It's, that's another one of these historical things people used to speak of layers. Because when you're bouncing a radio wave off of it looks like a layer, but it's really a pretty broad layer, especially in the African region. It's, it's more more of a region than a layer, but you hear people talk about layers. So, because the F region has long lived ions they can spread out and get entrained in the electrodynamics of the earth system. Because the earth's magnetic field has a strong interaction with these electro dynamical terms. You get two big belts of ionization in the F region, one on each side of the magnetic equator. And, and though those regions are subject to instabilities and dynamical blast product product processes that result, respond a lot to the earth's lower atmosphere and form another type of ion of ionosphere variability. But for the type of space weather that's solar driven that we're mostly speaking about today. It starts in the polar regions. Here's another ultraviolet image of the aurora again again if you were to see this in the, in the visible be super bright over here in the illuminated part this is this is the part of the atmosphere that's illuminated by the sun. And you get, you get certain emission processes in the ultraviolet, what the aurora can compete with those. And so this is a good visualization of, of where the aurora is, but it's very smeared out this is this is a sort of a discovery image from several decades ago. We're able to make a comprehensive image of the, of the aurora from from fairly high altitude. And so it's kind of it took 12 minutes to make this image and it's kind of smeared out of spatially and temporarily. From the space shuttle we were able to get dramatic images from low earth orbit. You can sort of see all this structure. It's actually occurring and there are this interesting color morphology with the red parts of the visible spectrum of the high altitude, and this blue green part at a lower altitude. This is the hard limb of the earth, the solid earth starts all the way down here. This is where the aurora is depositing most of its energy up around 100 kilometers. Here's a dramatic one from the, from the space station. This is time lapse photography. It's sped up by about a factor of 10. It's not moving around that fast and nor is the is the space station, but it nicely captures just how dynamic. These currents are that are connecting the magnetosphere in the ionosphere and are controlling and training aurora being the optical manifestation in this case actual visible light radiation. That's being generated by the impact of all those energetic particles they're following along with the current system. So, here's just just emphasize this this is high altitude red medium altitude green greenish blue. This is a photo. This is a photo I took in Alaska. This is a photo showing a moderate world activity. You can almost see the the curvature of the the world is stretches across the horizon. I'll show a few other images. This is one of the last ones that I actually took myself. Oh, let's see. Let's let's let's just recapitulate what's going on here. The optical emissions, they're being generated by electron impact processes that occur when reconnection occurs with the magnetic field of the earth and causes charge particles in this case primarily electrons to flow back down towards the earth. The lines connect in the polar regions constantly get the polar aurora on time or Polaris. They're moving along field lines because they're constrained to travel along spiral trajectories. And consequently the field line morphology controls the electrical field morphology and rural morphology. Here's another one of these nice NASA cartoon animations that sort of help you visualize that. Imagine that these were flex tubes spewing charge particles from the magnetosphere down into the atmosphere. Here, here, here they go. These are the electron moving along the spiral trajectories dumping out into the vacuum of near earth space until they counter the atmosphere. Once they encounter the atoms here they start hitting things. If they hit one of these gray atomic oxygen atoms, they might grow low red if they're high altitude, they're lower altitude. They are more likely to blow green although it's coming from the same atomic oxygen, or they might hit a molecular nitrogen. These two part blue things and emit light in the blue and in other ways like the aurora spectrum is much more complex than that. But that's a nice way to think about it and explains the basic morphology of the multiple colors that make up the aurora. There's atomic physics reasons why the red tends to occur at high altitude, green at lower altitude has to do with the long lifetime of the red emissions and so called O in the singlet D that is stable excited state because as a long lifetime, it's unlikely to admit at low altitude, because it will encounter some molecular atom and become collisionally deactivated before it has a chance to admit. How far down into the atmosphere do the electron penetrate? Well, it depends on how energetic they are. The deeper they go, and that therefore controls some of the phenomenology of the auroral emissions. They can get even below 100 kilometers into that mixed region of the Earth's upper atmosphere. But most of the auroral forms that are coming down here, 100, 120 kilometers, except for the very soft electrons which preferentially deposit at somewhat higher altitude. And again, these soft ones can emit even up above 200 kilometers. When they encounter the nucleotides, again, here's one of these plots with the nucleotide atmosphere and the atmosphere on the same axes, dashed lines through the nucleotides, solid lines for the ions, black solid line for the electron density. When the aurora comes in, you get an enhancement of electron density in the 100 to 200 kilometer region. And that is accompanied by the optical emissions, but also enables the currents to flow, the magnetic currents to flow through the ionosphere, because you have more conductivity here in the ionosphere because you have more electrons and ions. So just an overview, the aurora is usually pretty green in appearance, because that green atomic oxygen emission is pretty dominant. It takes a fair amount of energy to be able to separate out this sort of green-blue from the red at high altitude, but you can see that in the ground easier with photography. Here's some nice images from Alaska taken by colleague Dave Tritz during a really major storm. And this, you can get the red at lower altitude, it is a different emission, but it's another nitrogen emission that happens when aurora gets down at very low altitude. As the geomagnetic storm breaks up, you have all the structure occurs in the emission forms and presumably in the electric fields as well. Looking straight up one of these features is so-called aurora corona. You can see the convergence of the forms to the zenith as you look up, that's to say the magnetic zenith, and you look up the field line toward the pole. There's a lot of vorticity in those features. This is another one I took from Greenland, a fairly long time exposure, trying to capture just how much this feature is swirling around as you look up along this field line that you can even call it a flex to, may contain some clue as to the nature of the reconnection mechanisms. This is a nice evocative picture because it, because this is from another one from the NASA archives coming out of the space shell era. It captures nicely the idea that the energy source for the aurora is in fact the sun, but this is not the sun, of course, it's the moon. If it were the sun, everything would be too bright for us to see anything. And here finally is one of my own. You may recognize the locale if you're local. This is the, this is the older flat irons in the background. These are the indigenous trees. It's even November in this photo, and this is very overexposed, but you can see the NCAR Mesa lab in the foreground, partly illuminated. And at the Mesa lab, if you ever get to go back into it again, you may find this photo in a few different places. Just to talk a little bit about our efforts at NCAR to capture all this here. Here's an animation from a slightly older model, a little lower resolution, but capturing the effect of a storm as it impacts the ionosphere system, both the lower ionosphere, where you have the aurora very visible in basically ion density here, that changes the neutral temperature all throughout the thermosphere. And that changes the composition of the thermosphere. As I said, it was mostly atomic oxygen, molecular nitrogen, so look at the ratio of those things. That's quite variable, especially in response to these storms. That the combination of temperature and composition caused the electron density in the F region to also be quite variable as the storm progresses. And this is too much information at once. If you wanted to see that simultaneously, instead of sequentially, it would look like this with the aurora driving everything and the neutral atmosphere impacting the electron density in the ionosphere, just as the aurora electrodynamics also impact the ionosphere. So in order to understand that we need higher resolution models, we need better time resolution, we need more complexity and more realistic magnetic sphere physics. And that's all attempted by a new partnership led by colleagues. Johns Hopkins University, my physics lab. So it's a study for proposed NASA center of the drive center. And one of our main goals is to construct improved coupled models of this magnetosphere ionosphere atmosphere system. I'll just show some previews from what we're trying to accomplish. This is also a animation of the ionosphere response to a few magnetic storm. But a considerably more resolution and looking especially at that equatorial feature. It's, it's there all the time. When the storm hits, which is about now, it becomes completely dynamic changes the morphology entirely. You can see all the action going on at high latitudes. You can see that all of the magnetic field at the near the equator is still in charge. And we're going back to its baseline configuration with one arc on each side of the magnetic equator, which is going down through here. The storm settle a lot to say about reconfiguring the entire ionospheric system. Just show this one quickly. Wrap this up. The neutral atmosphere is also very dynamic response to one of these stories. This is a polar view of the north and south poles of of waves in the neutral density coming out of the oral region in response to day to day variability, which we're seeing now, and a storm, which is about to start. And these plots and the dots moving through the colors are data of density from a couple of satellites, just to show that you can capture most of the variability we see in the density. But we don't capture it perfectly not yet. Maybe not ever. But, but we've been captured somebody speaks nearly spikes in density. As the satellites move through these fake feet, these wave like features. Traveling atmosphere. Here comes the big ones. So yes, you can do too well on that one, but this one here. The density change very nicely. So this is pretty high resolution stuff. This is using the resolution comparable to the big models. So I'm going to wrap this up here. I'm just going to anticipate a question just in case I've written it down just in case you. This is something you wanted. Not an uncommon question. What about aurora? Well, you bet may have a better chance that we get more solar activity. What you really need is, is it seems space weather is, is, is good, is good weather. Filly dark spot does not be perfect. The aurora is always there. Usually very high magnetic latitude. So if you're not near a magnetic pole, you want some activity. So that this expansion of the world over brings it down to lower, lower latitude, lower magnitude can help you bring it bring it within your site range. Equinoxes are a little better than the solstice. That's not very. That's just a statistical variation. Forecasting is in its infancy, but there is a commercial government websites that you can go to to try to anticipate when there might be some moral activity. And consequently, you can position yourself at a place to see it. There's even apps. And here are some examples of graphics from NOAA space weather prediction center and, and, and other, and other locations in international nature. There's information out there with a little interpretation about this, all this having to do with solar wind measurements. You can, you can try to figure out when might be a good time to see the aurora. And then you can exploit geographic serendipity if you are in, for instance, Alaska, which is really well situated genetically for this type of observation. So I will wrap this up here. And be glad to field any questions. Thank you so much, Stan. That was wonderful. It was very insightful on kind of learning about what is one type of space storms caused by specifically solar driven space storms today. And one of the biggest things I learned was that solar flares and coronal mass ejections are different. And there's a lot more photons that are passing through space. But like from the corona mass ejection. So it's going to be really interesting to see how the sun keeps evolving in time. And yeah, so we do have a few questions on Slido. So I can ask Dan, would you be able to post up the questions and then Stan you can just go through the questions as they were asked. And, and I'll just let you handle those. So vulnerable are is our electrical grid to these coronal mass ejections was the last time the earth took a direct hit. We got some pretty good, pretty good hits in 2013 2014 and then most recently 2017. We mentioned this last solar cycle, totally different subject but this last solar cycle was not particularly strong. We didn't get a lot of big storms we didn't get a lot of, of, of radiation of variability in the solar output in the extreme But this upcoming this one that's just starting now, maybe, maybe stronger. There used to be a fair amount of skepticism about impacts on electrical power grids. I remember one of the NASA administrators a while ago said, Well, somebody please show me a picture of an electrical transformer. It's been knocked out by a space weather storm, and, and, but then people produced them. It's, it's not a common or frequent event. And as I said I believe without any with a total lack of expertise in this area but I believe that they are finding ways to engineer around this type of problem, which is, of course the answer to a lot of space weather problems is is to a great degree. I don't want to build systems that are robust enough to withstand space weather events which of course leads you to the question well how bad can it get. So, so I would say that serious power outages transformer a damage is is not a common thing. It can get out, but it is certainly possible. And, and one of the things that's been pointed out is that for these very large trans farmers which maybe have some vulnerability replacement can be very large scale and time consuming tasks. And, you know, you know, you can't just go, you can't you can't buy a, you can't buy one of these giant transformers on Amazon and just have delivered the next day, you know, it can be consequential if one of these, if one of these things goes. So, you know, there's a lot of concern about analogous processes such as electromagnetic pulses that can be human induced. That's not an area where I have any expertise, either but I know that there's a lot of interest in certain segments in that subject. Thank you so much and it takes a lot of engineering to make sure to work with you to be able to keep our infrastructure. Yeah, to some degree, to some degree the space science side of this, it can be considered to be putting, putting up a limits on things. You know, we think of this an analogy, you know, by using the word space weather we think well, that must be analogous to troubles here at weather and well what do you want to do with troubles here at weather. Of course you want to forecast it. That's why I get you so far. Okay, so why do Aurora formed a different altitude is this by different colors. I started to touch on that but it's really a whole much longer story. There are two primary things. One is the change in composition that is the molecules and atoms that make up the upper atmosphere changing over from atomic oxygen at high altitude to to mostly molecular oxygen, molecular nitrogen, and also molecular oxygen at lower altitude. If you, if you can bear to think of 100 kilometers is being low altitude, and who doesn't. Then, then you get a different mixture of colors as things change also the storm it's storms themselves change the composition mix. With that, you get basic atomic physics, things that are long lived, meaning long have long lifetimes against radiation preferentially emit at high altitude, because when they get down to lower altitude, before they have a chance to admit. They get what we call collision collisionally deactivate they undergo collisionally activation, they run into something else. And, and, and that collision takes away the extra energy of excitation before it can have a chance to admit. So you get a complex interplay of all these different things. And, and, and that explains the, that explains the fact that there is so much variability in the oral spectrum. I mean, means that it's a daunting task to take, take a driving mechanism and, and reconstruct what the oral spectrum might be or vice versa to look at an oral spectrum and figure out what's going on. Awesome. Thank you so much. Dan, can we see what the next question is. What's the scientific rational for high geomagnetic activity near the equinoxes. Oh, it's a. That's an even longer story and, and, and maybe a little bit controversial. It's it's it's called the Russell McPherson effect, because Chris Russell and Bob material interest identified it. If you look statistically at, at indices of geomagnetic activity, you will see a slight preference for the equinoxes. And that has to do with the way that the, or the theory is that that has to do with the way that the Earth's magnetic field lines up with a solar magnetic field the so called interplanetary magnetic field. And when, when during the equinoxes you have a more favorable configuration for for magnetic reconnection. It doesn't affect the likelihood that they'll be a big solar storm. If there's a big solar storm, a big criminal mass ejection that that's not going to care where the earth is in its orbit, whether it's equinox or Celsius. But there's a lot of lower level activity that's going on all the time that that can be slightly amplified by this alignment between the solar magnetic field and the Earth's magnetic field. And of course, that alignment also can affect the way that a major solar storm, criminal mass ejection can interact with the earth, but probably have them as less effective as magnitude. Thank you so much. That was, that is like a whole research in itself. Dan, can you please share with us what is the next question that we may have. So, the articles proton is a topic of nuclei from the skinny also contribute to the Rara. And if yes in what way. The, uh, uh, this, the, um, they, they, they contribute to, to impacts on the Earth's atmosphere. They don't tend to make as much in the way of visible manifestation or ultraviolet. You know, of, of light emitted from the aurora. They tend to be much more spread out than these highly structured forms that come. Basically from the atmosphere of the earth. But they're, you know, there's so many aspects of solar activity. I don't have time to touch on all of them. One phenomenon is known as solar proton events. These are, these are in fact particles from the side. I tried to drive a couple of messages. The ionosphere is, is, is mostly neutral. Aurora doesn't, isn't just particles from the sun. It's really more like particles from the magnetosphere. Solar proton events really are particles from the sun that are energetic enough to penetrate the magnetosphere. And the, the deposit their energy at even lower altitudes, where they contribute to the chemistry of the middle atmosphere. And in a minor way, but, but, but they can impact the chemical processes through the same sort of mechanisms of associating and even ionizing things. But they, but in terms when we say aurora, we think of the visible manifestations and the stuff that you can see, either from space or from the ground. They don't tend to contribute as much to that aspect of the phenomenon. They're harder, harder to see a solar proton event, unless you have specialized instruments in space. Yeah, there's just so much going on up there. It's, it's crazy because I just kind of worry about what's, what's happening in my house. Yeah, well, I guess some people, people get caught up in this stuff to too much sometimes I mean, it's, it's not like the auroras coming into your television set and electrocuting everybody in your house it's got more to do with currents flowing either at high altitude or through very long connections. Awesome. Thank you. And then we do have a final question Dan, if you can post it up and it asks more, more so what's your day like at work and I kind of wonder if this can be kind of like what kind of work. What are you doing? Are you doing the computational aspect of the research? Is this, is this, is this a, is this a question for the last eight months or so, or a more generic career based question. I think it might be the career based question. I think so. And of course, since most of my work is done on computers, you know, we have a great good fortune of being able to continue working during the, during the stay at home environment, although, like everybody, it requires a lot of reorientation and a lot of different ways. But that aside, my, my daily work is, is on largely on contributing to my areas of expertise as they pertain to this large scale model development to which I alluded and, and, and in utilizing measurements, primarily from space based vehicles from that primarily from NASA but also from ground based source and from sort of hybrid sources like GPS I mentioned disruptions of GPS, we can use GPS measurements now known as GNSS measurements to infer ionospheric processes, properties, and, and, and both both space based and ground based aspects of that type of measure. And, and using those measurements to try to tell us if our models are doing right thing. If they're any good if they are trying to figure out what areas they need improvement. So model that a comparison is a large part of it. And, and then, and then communicating the results of that research, both in a specialized and general audience. Preparation of talks from meetings and writing results for publications. And then, of course, particularly as years go by one becomes and trade more management processes, and then trying to organize teams of scientists. And, you know, these, these, these giant models are, I haven't said much too much about our new approaches to this high resolution ionospheric service your modeling, but it's a lot of it is, is built upon numerical processes that are used in the big car climate and weather models. We can use a lot of that of those mechanism mechanisms, much higher altitude basically moving out of the regime for which they were intended. And so consequently you're participating in an enormous model development process which takes very big teams of scientists, each working on different aspects of the process and that takes a lot of organization, a lot of meetings a lot of management. And so the reality is, is that, especially this, the National Center like again car. The reality is, is far from the canonical idea of the science scientist working alone in his office. Equations trying to, trying to make a contribution in a isolated fashion. It's much more collaborative process. That's awesome. And I know that you mentioned the Center for Geo space storms with a lot more work that's going to be coming out in the next couple of years so we definitely look forward to being able to follow your path and you're like all of your collaborators the work that comes out from many universities, many universities and other organizations are involved in that, which is its own challenge for long distance work. Yeah, especially right now with travel restrictions but it's great that we have the technologies to be able to talk with each other, even from our own homes. And with that, I don't see that we have any other questions. So I would like to just say thank you so much Dr Stan Solomon for sharing an inside view of what are these space storms and some awesome photos of the field photos that you've taken yourself. Thank you for the opportunity. Great. And for everybody watching thank you so much for joining us tonight. I love having these lectures I know we've been having a lot of conversations with scientists. And so we're going to continue to do a little bit of a lot. If you are, if you had registered will send out the survey to get some feedback from you all. That's just how we're doing for this NCARC floor series and things that you might want to see in the coming new year. Well thank you Stan, and thank you everybody and with that will say goodbye, and we'll see you next time. Okay, thank you.