 Whether you're here with us at the Mesa lab or joining us virtually, thank you so much for sharing your time with us today for this Explorers Series lecture, Air Quality from Space with Dr. Peter Nelavelt, I am Dr. Evie McCumber, and I am an educator here at the National Science Foundation's National Center for Atmospheric Research, or NSF NCAR. NSF NCAR is a world-leading organization dedicated to understanding Earth system sciences, including our atmosphere, weather, climate, the sun, and the importance of all of these systems to our society. I am really glad that you all are joining us today to learn more about how satellites in outer space can tell us about life on Earth. For this event, you'll be able to ask Peter Nel questions following the lecture, and Olia will help moderate so that we can ensure that we hear from both our in-person and virtual audience. If you're in-person, you can just raise your hand, we will run to you and give you a microphone, then you will have some time to ask your question. If you're joining us virtually, you can ask your questions using the Slido platform. If you are virtual, if you scroll down this web page, you can see the Slido window just below where you are seeing the live stream of this event. If you haven't already, also this applies to you, go ahead and click on the green join events button, and you can go ahead and ask questions on the Q&A tab. Peter Nel also has a few poll questions for us. Don't worry, it's not a pop quiz, you don't need to know all of the answers ahead of time. So for both our in-person and virtual audience, you can respond on Slido. If you are in-person, you can use your phone or laptop to navigate to Slido.com and enter the code hashtag Explorer Series. And definitely be sure to join Slido to add your thoughts to our word cloud. What do you think of when you hear the word air quality? Because we are going to get to that really soon. This event is also being recorded and will be available on the NSF NCAR Explorer Series website if you want to revisit it. With us today, we have NSF NCAR Associate Director and Scientist Peter Nel-Levelt. Professor Peter Nel-Levelt has been Director of the NSF NCAR's Atmospheric Chemistry Observations and Modeling Lab since June of 2021. Her scientific expertise in performing and interpreting satellite observation of the Earth's atmospheric chemical composition in the context of climate change, air quality, and the ozone layer. In 2018, she received the NASA USGS PCORA Award and in 2021, the AMS Special Award on behalf of the International Omi Science Team. In April of 2021, she was knighted in the Order of the Dutch Lion. Dr. Levelt studied chemistry at the Free University of Amsterdam, obtaining her master's degree in physical chemistry and then her PhD in physics. Professor Levelt became the principal investigator of the Omi instrument, which launched on NASA's EOS Wara Satellite in 2004 and is still responsible for the international scientific program of Omi. She is a scientific founder of the Dutch ESA Tropomy Satellite instrument that launched on the ESA EU Sentinel-5 precursor in 2017. Dr. Levelt was the head of the research and development department on satellite observations at KNMI, the Royal Netherlands Meteorological Institute in the Netherlands, which she's still affiliated with. Professor Levelt is a professor in remote sensing of the Earth atmosphere at University of Technology Delft, which is also still ongoing. Dr. Levelt is a member of the Mission Advisory Groups at ESA for the EU Copernicus Sentinel-4, Five Missions, and has shared ESA's S-5 precursor, Tropomy Mag. She co-chairs the NitroSat mission, one of ESA's Earth Explorer missions in phase zero that focuses on the nitrogen cycle. Now, before I turn it over to Peter Nell, let's check out your thoughts on our word cloud. Paul and Joey, may you please share a slide of those? Let's see what you think about when you think of air quality. Pollution, the measure of how perfect the air is, pollution levels, air pollutants, smog, clear oxygen. Peter Nell, what do you think of these answers and what their add-ons do, how they do? And there are reasons for that to do that and I hopefully show some of that in this presentation. Thank you. So, thank you for the very nice introduction. I'm going to talk about air pollution, air quality measurements from space and I'm wondering how I can first slide on. Okay, good. So, I will talk about two satellite instruments which I'm originated. I'm still the principal investigator, so the scientific leader of one of those and the other one, I was the scientific founder. But I will start with explaining a bit about why is it so important, this atmosphere composition. Why do we need to have this knowledge for life on Earth? And I will also show you in this presentation that when you measure air quality, that you measure indications of human activity. Here are some sounds. Okay. And I hope to be able to convince you that we can indeed see human activities like traffic and industry with satellite instruments from space. I will end with talking about Africa and that's a new ambition we have here at NCAR to perform satellite measurements over Africa. So, I will start with this image and this image shows you air pollution, one specific component, it's called nitrogen dioxide, measured by the second satellite instrument, topome. And you see it's a global measurement. That's one of the advantages of satellite measurements that you measure the whole globe. That means that when you have a measurement over Europe or the United States or Asia that you can compare these measurements directly. And that's a very, very big difference with, for example, ground-based measurements where you can ask yourself, and there are measurements in another country, are they calibrated well? How do they treat the instruments? So, you have questions about that. But when you have one instrument measuring the whole globe, you can directly compare these measurements. That's a big advantage of satellite observations. There are also disadvantages, but that's one of the big advantages. So, what you see here is nitrogen dioxide. Nitrogen dioxide is produced by fossil fuel burning. So, that means that you see traffic, industry, and power plants. And the red values in this image are high values of nitrogen dioxide. And the blue values are very low values and all the other colors are in between. So, you clearly see that when you have red values that they are on areas where a lot of people live. So, you see Europe, you see the Poe Valley sticking out there. I can do something with this for that. Or I have to put it here. You see it in the largest big red thing is the Poe Valley. We see China and we see also the major cities in the United States like LA and Washington and New York. When you call more to the south, you look at South African, South American Africa, you see a little bit higher levels of nitrogen dioxide. They are related to biomass burning. Basically, mainly eco-culture practices in Africa and South America, which they still use for the eco-culture COP. So, they burn on regular times during the year, they burn their land and that's what we can measure. You also see that we can measure ship emissions. One of the largest ship emission tracks is between India and Indonesia. And we can also measure that from space. Okay. So, now there will be a slido question related to the red spot in South Africa. Yes. And that question is, what may be the main cause of high nitrogen dioxide levels in Johannesburg, South Africa? What do those answers look like to you, Peter, now? The main cause of that red spot is not biomass burning. It's power plants in combination with industry. So, there is a high field near Johannesburg. I've been there in 2017. And there are 12 power plants with a lot of industry around it near Johannesburg. And they produce a lot of pollution. And that's why we see that big red spot near Johannesburg. Yeah, I can go on. Okay. So, we make global measurements. But the measurements are so good that we can also focus on specific areas in the globe. And what you see here is the Netherlands. That's the country I come from. And you see a lot of red stuff there. We have quite some air pollution in the Netherlands. We are a very high populated country. And you see, for example, red bloc around Amsterdam, where I still have house. I come from near Rotterdam, the harbor and the city, Antwerp, Hoere area. And you see also Schiphol. And that is, you might have been there because it's the airport near Amsterdam. And with this new instrument, with Tropomi, we're able to measure that pollution from Schiphol as distinct from Amsterdam. So, it's not one blob anymore. We can really isolate the pollution from Schiphol. And we're not able to do that before we had this instrument in space. But now I live here. And that same instrument also measures here. So, I asked my lab, the lab I'm now leading is starting to work more and more with the Tropomi data to make this image. And you see the nitrogen dioxide pollution again. You see Denver, you see Boulder, you see all the cities. And you also see the highways. So, that's what we can measure nowadays from space, all this pollution with a very, very high spatial resolution. I think we have a slide of question now. What percentage of our atmosphere is carbon dioxide? I am surprised by the answers and the fact that what is the correct answer, Peter, no. It's the first one, less than 0.1. I would have expected 28 or something higher. So, that's very, very good. And that's correct. So, let's look at the composition of the Earth's atmosphere. And that's this one. And what are the main components there? So, we learned at school about 80% is nitrogen, 20% is oxygen, 1% is argon. And then we have a very tiny amount, 0.36%, which basically has all the trace gases I'm going to talk about in this presentation. So, it has all the greenhouse gases, CO2 and methane. It has the complete ozone layer. It has all the air pollutants in the tiny amount. And it's actually striking to think about that, that it has such a strong influence on life on the Earth. And for me, personally, it's even more striking that you can measure all these trace gases from space now. Using satellite instruments, circling the Earth at around 700, 800 kilometers altitude. Okay. So, I call now to why do we need to study the atmosphere composition? So, the area we are currently living in was called by the Dutch Nobel Prize winner, Paul Kruitsen, the Anthropocene. And the Anthropocene refers to the fact that we put all kinds of emissions in the atmosphere. And you see Paul Kruitsen there on a photo on the roof of Canemai, the Dutch metalosphere I used to work. On the day he got the Nobel Prize. He was visiting Canemai and we got all the media on top of that. I was at that time already working at Canemai. But Paul was also the one who actually initiated the lab I'm currently leading here at NCAR. He was the first director of this atmosphere chemistry lab. And on top of that, he was the originator of the idea to put spectrometers in space to measure air pollution from space. So, Paul had quite a strong influence on my professional life. So, when you look at the atmosphere composition, there are three main themes we study. One is the ocean layer, the coffee of the ocean layer. Ocean layer is important for life on Earth because it protects us against the harsh UV radiation. For that, we can get skin cancer, for example. It's important for air quality. And also for climate change with the greenhouse gases. And you see here the major emissions. So, you see on the top left the so-called CFCs, these are mainly caused by cooling agents we use and which destroy the ocean layer very, very effectively. We also have a lot of emissions from industry and traffic and of course from biomass burning, agriculture burning or wildfires. So, the atmosphere is a chemistry is fascinating but also very challenging. If you really want to understand it, and this is a kind of schematic overview, then you need to know a lot. So, you have to have knowledge about your emissions, some cities from traffic but also natural emissions from volcanoes. You have to have knowledge about chemistry, homogenous chemistry, heterogeneous chemistry, transport, exchange with land, with ocean, solar radiation, impact on photochemical chemistry, for example. So, we tried to understand all of this in the lab I'm currently leading with many, many methods. One of them is satellite but we also use models and count-based instrumentation, aircraft instrumentation. Today we'll only talk about satellites. So, you further see a set of base gases. Completely on the left, you see CO2 and methane and CO2 and methane are the two most important greenhouse gases. Then you see a whole list starting with nitrogen dioxide, silver dioxide. These are old air pollutants, so they are toxic. And then you see ozone and air source separately and they are on a different position because you have a dual role. They influence climate and they influence they are all both toxic. So, they have a dual role in the air pollution and the climate. And what is also important to recognize is that ozone is not something we emit. It's formed in the atmosphere by chemistry from methane with the air pollutants. And air source, at least 50% and probably more, is also formed in the atmosphere, so not directly emitted. And that is also formation with the same set of chemicals. So, that means also that the air pollutants and greenhouse gases methane are linked in their chemistry. And that means that when you make policy for air pollution or for climate, that these policies will impact each other. And in most countries, the policy makers for air pollution are in different departments and policy makers for climate. So, that's one of the things we're dealing with now with the COP meetings basically. Okay, so one slide about the ozone layer. So, you see here ozone measured by my first instrument, which is still measuring actually, OMI. For 2018, we can make this movie every year. And you see basically the formation of the ozone hole over the Antarctic over the South Pole. It starts around and the forecast finish about half December. So, now when you see this dark blue and black, it's really all the ozone between 1420 kilometers has been destroyed by this cooling agents. Very, very effectively within two weeks. So, it's very, very aggressive. For this, we made the Montreal protocol to protect the ozone hole to get the recovering and we're successful actually in that. So, the Montreal protocol tries to limit these cooling agents, the CFCs. And we can measure with other satellite instruments that that is effective. And we also now see it in the recovery of the ozone layer. So, what is good to know is that the assessment of the Montreal protocol is fully based on satellite measurements, mostly based, let's say, 80, 90 percent. For air pollution and greenhouse gas assessment of protocols, it's mainly based on count-based instrumentation. So, that's a big difference between this type of protocols. And one of the things I'm advocating for is also to start satellite data to use that for air pollution and greenhouse gas monitoring. And what is further important to know is the Montreal protocol has also a big win-win for climate, basically, because the CFCs are very, very strong greenhouse gases. And by reducing them, we actually have a smaller climate change than we would have had without the Montreal protocol. And at the point we put this Montreal protocol in place, this was not, we were not really aware of it. It was not part of the discussion on that level to put the protocol in place. Okay. So now I go to the other themes, air pollution and greenhouse gases. I start with air pollution. When we think of air pollution, we usually think of China. And here you see a clean day for a Chinese city. And this is a polluted day for the same city. This is not fog. These are tiny particles. These are aerosols. And everyone who has been in China, and I've been there twice, has seen this. If you're there a week or two weeks in Beijing, Nanjing area, you will see both situations. So that is a lot of pollution, but China is not the only country with pollution. So when we look at the air pollution globally, and this is an image which is made by the World Health Organization, and you see the impact from outside air pollution on premature death. We have 4.2 million people who are dying earlier than when we would not have had this air pollution. So that's quite a big impact. And it's actually striking to realize that you're not really aware of that. So when we are talking about pollution of food or water, we are very, very aware of that. We are not going to eat or drink that. No way. But we have flushing air, and we breathe it every day. And we are not really, really aware of that we do that. And we can live months without food, days without water, and only a couple of minutes without air. So it should be something which we could raise on a higher level of attention. I think I have a slide on that one. Following up on this, could we please bring up the slider question that asks what place in the global risk factor for premature death is taken by air pollution? That's a high ranking. So this, the people who are here are really aware of it. That's clear, because it's the fourth place. And so then we go to the next slide to see that. You see it on the lower right. So what we look here at is a result from a paper in the lens set. And here they look at air pollution inside and outside. So in-house, outside. If you combine that, then we are talking about seven million premature death a year. And in that listing, if you take that listing, then it's the fourth global risk factor of which we die prematurely. And we have very high rates in Africa and Asia. And that's what you see in this image. Okay, then climate. So climate change is more and more in the attention. And we all know that CO2 is the largest greenhouse gas. And you see that here in this image, which is one of the IPCC images, you see that on the horizontal axis, we have the effective radiative forcing, which basically tells you how large the heating effect is of a certain greenhouse gas. So CO2 has the largest bar. And that's the most important one. But the next one is methane. You see two colors there if you're not colorblind. And the orange one is the direct effect of methane, the heating effect of methane. The green part is the heating effect of ozone. And as I told you, ozone is only formed in the atmosphere. You don't admit it. And it's formed in chemistry initiated by methane. So when you have methane as greenhouse gas, it has an effect, but also the formation of tropospheric ozone due to methane has an extra heating effect. So this is something new, which we are now more and more aware of. I think last 10 years, it has been a major topic at the COP and also the IPCC report to make that clear. And that means that methane has become a more important greenhouse gas because the effect is so large, larger than previously thought. And on top of that, methane has a much shorter lifetime than CO2. So when you reduce methane, you will be faster, probably already in decadal timescale, effective in cooling basically or not so much heating of the atmosphere. And then the last point, I think that made it more and more visible are the satellite measurements. So tropomy is the first instrument that really can get global coverage of methane measurements. And the instrument was launched in 2017. And it is really, really effective in showing how much methane there is. And I think that this type of measurements and visuals, which you will see later in the talk, have a big impact in how people appreciate this type of information. So I think that also had a big impact. So we now have the so-called methane pact. And also in the last COP 28, that is an important development and is now signed by 155 countries to reduce methane with 30% in 20 or 30 years from now. Okay, now I'm going to talk about the satellite instruments. And I talk about the European part of this type of instrumentation. And the instruments we use, we call solar backscatter. So these are spectrometers. And I will explain in one or two slides further how that works. You see here a whole list of instruments, sort of top five with all these fancy names. They're all designed and built by mainly by Dutch industry. So we have a very, very, yeah, elaborate industry in Holland who is really, really good in designing and building this type of instruments. I will talk about OMI, which is the third one, and top OMI, which is the fifth one, the orange. You see also two green bars, and these bars are for future instrumentation, which Europe is going to launch. So central five will be a follow-on instrument for top OMI. And central four will be the first instrument in a geostationary orbit. So all these instruments are what we call polar satellites. So they fly from pole to pole around the Earth at about 700 kilometers altitude. But central four will be a geostationary satellite. And it means that it will move. If you hang on to above the US, it will move with the US. If it's above Europe, it will move with Europe during the day. So that means that you can make measurements during the day. And we can make about eight to 10 measurements during the day with a geostationary satellite. With a polar, you only cross once a day. And for OMI and top OMI, that's about 130 in the afternoon. Okay, so OMI and top OMI. On the left, you see three very happy PIs receiving the PICORA award for the OMI instrument. So it was launched in 2004 on the Iosara satellite. And it's myself in the center. On this side is Joanna Tamine. It's my Finnish copie because it's a Dutch Finnish instrument, OMI. Electronics comes from Finland. And on the right, you see Joanna Joyner and she works at NASA called Space because it was launched on NASA satellite. And it's very, very rare that you have three female PIs in this space community. So there are many things why we're very proud of this achievement. What OMI was able to do, and it was really an acclaimed changer, is measuring daily global covers for the whole atmosphere in one day every day with very high space resolution, 13 by 24 kilometers. Then with top OMI, we were able to improve this. And you see here top OMI on the right is much larger instrument than OMI for many reasons. And you see it here in one of the clean rooms in Airbus in the Netherlands. And that instrument went to three and a half by five kilometer pixels or 16 times improvement when you look at the surface. And also still daily global covers. Okay, so how do we measure? The measurement technique. So we use the sun. The sun is our lamp. And what we basically do, we have a spectrometer and the spectrometer unravels this white light to the rainbow colors. You see that rainbow on the horizontal axis of the image on the right. So most of the time we fly from pole to pole. So we look like this downward from pole to pole. And that is basically what you see here, where the light is scattered and absorbed by the atmosphere. So it reflects it scattered absorb the coast back coast back basically to the satellite instrument. And that gives you the dark curve, the dark blue curve. Once a day we look directly at the sun. Because the sun is our lamp. And we have to calibrate the lamp. And we do that on a daily basis. And that gives you the light blue curve. And when you look now at the numbers on the horizontal axis, you see 250, 500, these are the wavelengths. And you see that all lights from the dark blue curve below 300 nanometers is disappeared. And that's caused by the ozone layer. The ozone layer absorbs all that light, protects us against this harsh UV radiation. You also see some dips, deep dips in this, what we call spectrum. And they, they are connected to specific trace gases. So these trace gases have a kind of fingerprint. They absorb at the specific color of the light. And we know exactly which color they absorb. And the deeper this dip is, the more trace gas there is. So it's basically absorption spectrometry. And it's a very, very simple technique. But in practice, it's very complicated because you have to know a lot about the atmosphere to catch accurate amounts out. But the basic principle is very simple. Okay, so this is the innovation of only. So what you see here is a two dimensional detector. You can compare it to what you use in your, in your phones, where you make photos with. So you have two sides of two dimensional detector. Only was the first to use that. And that enabled us to put on one axis, the rainbow, the wavelengths, and on the other axis, spatial information. Previous instruments had to have a mirror swapping over the earth, basically. But we can measure that whole, what you call SWAT, you see the word up there in one go. Because we used a two dimensional detector. And all instruments after OME, US, Europe, Asia doesn't matter. They all use this new innovation. Because that enabled us to get daily global covers with a SWAT of 2600 kilometers. And at the same time, very high spatial resolution, because we had all this every pixel in the detector corresponds to a different point on the earth. So when you have one orbit, we fly from pole to pole. This is one orbit. When you fly around 700, 800 kilometers altitude, it takes you 110 minutes. And then you see this is a measurement of top OME, the second instrument, we look at clouds here. And you see that we can seal these clouds because we use this two dimensional detector. When you calculate in 24 hours, because the earth is turning below it, we have 14 orbits. And when you do 14 times 2600, you almost have the equator. And that leads to this daily global coverage. Okay, so now I first talk about OME. So OME gave three, four big new invention, inventions, what we could do with the data for to understand the atmosphere composition. And I will explain three of them. So you see her OME nitrogen dioxide again, it's a global image. Same data set, you can also look over Europe. And of course, you can make an image over the Netherlands. And please try to memorize this image more or less. Yeah. Okay, so here you see the new findings due to his instrument, it was caused by many factors. But the main factor is, is the daily global coverage and high spatial resolution, which really enabled us to pinpoint emissions, and to have a lot of data. So with that, we improve the air quality forecast. We improved environmental monitoring. So when you put policy in place to reduce air pollution, can we see that from space that it is reduced or not? And we also used it to calculate emissions. And that I will explain these three slides from now, what I mean with that. So I will start now with the environmental monitoring. NASA's satellite is the past decade. And its initial findings have shown us a lot about the state of our atmosphere. The satellite detects gases like nitrogen dioxide, like how included from cars and power plants. The data shows us that the United States and Europe have some of the highest emission levels in the world. But it also shows us that over the last 25 years, nitrogen dioxide levels have dropped by up to 50% in both regions, thanks in large part to new rules that protect our air. At the same time, in China, India and the Middle East, this pollution has grown dramatically. So imagery like this can help us see what actions are working and where we need to focus additional international efforts. And it proves that we all need to work together to protect the one planet we've got. So I'm always amazed when I see this movie that he can explain my complete research field in one minute and 10 seconds. It takes me an hour to talk to you and then hopefully I explain some of it, but it's really extremely good communication. And of course, we were very, very proud because all the data you see are from the only instrument. And yeah, president of the US is talking about it and not a lot of scientists who have that experience in their lives. Now the second one was air quality forecast. So air quality forecast is like a weather forecast, but then for atmospheric chemistry. And one of the things you see on the news in the evening when you look at the weather forecast they use this satellite data. You see these images usually there's a geostation in the satellite. So you see the clouds changing during the day. But one of the things that's really important for that type of forecast, whether or air quality is that you have to data fast down and calculated to the product you want to use. So in the only project, I took the decision that we would like to have the data in what we call near real time. That means within three hours after measurement. And that's what we did. So the only measurements you see there NRT stands for near time are available within three hours after measurements everywhere around the globe 24 seven. And with this data, you can improve your air quality forecast because you have a check for real measurements if your model forecast is correct. So we use that for global air quality forecast also for European air quality forecast. Also in the US these data are used also only by NOAA for example for the air quality forecast. And now with top only data everyone is working to catch also to higher solution better forecast to really use this high resolution data for a country like the Netherlands. Okay, the third one is emissions. So what you see here is a pipe of industry or power plant and it has a pollution plume. And a plume that is transported by the wind chemistry takes place. At some point you have a certain concentration and that is what you measure with satellite. We measure the concentration of nitrogen dioxide. But when you want to say something about emissions, you have so to speak to calculate backward in time, push the plume back into the pipe because you want to know what came out of the pipe. So you calculate chemistry backward in time and transferred and then you know the emission. And that is a technique that was that model technique has largely started to develop it only because you need a lot of data to do that accurately enough. And what you see is on the right have one example. What that means on the top, you see the Middle East nitrogen dioxide. It's what they call a bottom up emission map. It's based on information from government and industry. So it's a paper exercise basically. No, there's barely any measurement going into the map above. When you only use the only other two data, you can catch the map below with this new technique. And we can calculate that map in one month, one or two months time frame, but that's the amount of data we need to get a good map. And you see these maps are very comparable. What you also see is that there are a for 2010. Why is that? It's because this Middle East map is the most recent we have. Because this cough, this bureaucratic paper exercise takes a lot of time. And of course, for the United States, you could have it from this year, but from Middle East, it's a little bit more difficult to catch. So I'm already advocating for a long time to use satellite data to update these maps, not throw away the papers exercise, but combine the satellite measurements and the paper exercise to just make it more up to date. And we can do that with the current satellite measurements. Okay, now I go to the second instrument, top only. So top only is part of a huge activity in Europe. It's called the European Union Copernicus centi Nells. And they are launched to monitor climate basically. So there are land instruments, instruments that measure the ocean. And you have instruments that measure the atmosphere. And we actually have three instruments here that measure the atmosphere composition. And central five P on the lower one, that's the one with carries top only. You see a small mimic of that's there on the table. That's the central five P satellite carrying the top only instrument. And you see central four and five of which I already talked, which are follow on instruments. So central five will follow top only central fourth will be our first geostationary instruments in Europe to measure atmosphere chemistry. I'll come back to that later. So what did we improve from only to top only? We have a higher space resolution. We have a higher sensitivity per measurement. We added two channels, one to correct for clouds, because we measure in a wavelength range where you cannot is the same as your eyes. We cannot look to our cloud. So the instrument cannot do that either. So when we have a pixel with some clouds in it, we want to correct for that as good as possible. And for that, we added the channel to do that. And then we have a channel with measures carbon monoxide, which is also an air pollutant and methane, the second most important greenhouse gas. And from I will show you results from 19 dioxide again, and methane. But here is the photo. You see two very happy PIs in the center. When the top only launch was successful, we're here at is a is a stack at North Wijk in the Netherlands. So I'm on the right on the left. You see the pain fervent who is now the PI of top only working at the Dutch Met Office. And why are we so happy? So one of things a lot of people don't know is that the lounge is still the most risky part in a project like this. So the lounge is is very, very exciting. And we started to think about top only one year before only was launched. So 2003. In the year 2003, we had the first ideas about top only. And we launched the instrument 2017. So this is really, really long, long, long, long time commitment. And then of course, you really would like it's you have only one instrument. There's not the second one somewhere on the ground to launch. You know, so this this is this is your project. So that was it's always really, really exciting. Okay, so here is the first measurement we made with top only. It's about one month after launch. And we use only three wavelengths. And we can measure with three wavelengths, clouds, land, ocean. But top only measures 4000 wavelengths. You see here for spectra of that. And we have 20 million count pixels per day. And per count pixel, we can get 10 to 15 trace cash products. And this is run operational 24 seven within three hours of the measurement, you have these data. So it's one terabyte of data per day. So this is really huge. I will talk only about two trace cash so 19 dikes I think and meeting. So this is the first measurement of top only on nitrogen dioxide. And this is the moment that all the scientists working on this instrument for years and years and years are running through the hallways of KMI. Because this is your this is what you do it for. Why did we run? Well, I hope you still remember the only nitrogen dioxide image. But what you see is much higher spatial resolution. That's very tiny. We are 200 by 150 kilometers. That's that's our size, more or less. And what we also saw is that we see air pollution plumes. So we see the plume going from Amsterdam over the North Sea pushed over the North Sea, due to the southeastern wind we had on that day. From Rotterdam from Antwerp from who are so she the movement in the pollution. And that is the first time we can measure that. Top only is the first instruments globally who can measure that you cannot measure that from crowned because you don't have that whole plume in one view. It's difficult to measure from aircraft because you don't fly fast enough you need to kind of what we call synoptic view to see it in one go. And so this is really really new material. And you see that on the right 10 days later, we have to wind from the North Scandinavia, North Sea, very clean. That's what you see. And you see the plumes going to the South. So that was and we also directly saw that the measurements were good. If you look a lot to this type of images, you can directly see it. If the instrument is good and be so likely this instrument is really good. So, well, we don't only mention the Netherlands. So these are averages over April 2018. Also Africa, Middle East. And on the right, you see India. And you see that we have a small movie there. And if you look, you see the issues in the southern part, you see small plumes moving with the wind from day to day because this wind field changes from day to day. And these are most of them are power plants. So we see power plants from space. And we also see where the pollution plume from that power plant goes to. Okay, so one of the things that really made Topomi famous, I think, from our perspective, was the COVID crisis. COVID was dramatic for everybody. But one of things that happened is that no one transported his or herself anymore. So we stayed at home. So there was no traffic. And that has influence on air pollution. So it was for us a kind of atmospheric experiment which we never would have had. And we were, we were all working from home, like you did. But we were approached by the whole world for our data to look if they if we saw a decrease in air pollution due to the fact that we were working at home. So we had the New York Times, Washington Post, ESA with several outings also Dutch television. And it was was a very, yeah, for us a very interesting time to be. So one of the things we did was to look at China. So on the left, you see February, March efforts 2019 over China. You see a lot of pollution. Then on the right, you see one year later, February 2020, the lockdown in China, which was really, really stringent. And you see a huge decrease in pollution. And that is mainly caused by transport, no transport, basically, no cars. Power plants continue to work because, yeah, otherwise, everyone freezes industry for large part, but transport, that was cut down. And then one month later, surprisingly, one month later, I'm still surprised by that. China, when I look back, because I have to think we're still not completely over this whole period. But China went back to work. And you see that in an increase in the air pollution. So you see really human activity, what we do, impacting air pollution, and we can measure that from space. Well, ESA had this European space agency, had several outings. And you see here, again, 2019 compared to 2020, with a large decrease in air pollution due to the lockdown. And in most large cities like Paris and Madrid, it was almost 50% decrease in air pollution. Okay, now I'm going to talk about methane. So what you see here is methane measured by topomi. It's an effort so for about six weeks, starting one month after lunch. And you see that we can measure methane with a global view. And after seeing all these 19 dioxide images, you think, well, why not? But that is really special. Because at that time, there were only a few other instruments measuring methane. And the most important one is cosets still working. And you see the image of coset on the right, lower one, and that is not a globe, you don't have this coverage over land. And we could provide that due to this two dimensional detector in the end. So that we have 1000 times more measurements in coset, which means that you can look for emission sources. When you only have a stripe, you also miss a lot of emission sources. But when you have coverage, you can measure them. And what we also did, we did a direct comparison with coset, which is a very accurate methane measurement. And you see that's more or less one to one line. That means that there is no difference between those two measurements. And that is also very, very exceptional because methane retrieval is really, really challenging. And usually it takes you years to get the right amount. But this instrument was so good that we directly were on this one to one line. And that was also really, really surprising. We didn't expect that. So methane, the second most important greenhouse gas has many, many sources, and to between the sources and natural sources. And the next slide last slide or question, which we're going to bring up is which of the following methane sources is the largest anthropogenic source of methane? And we have livestock, gas, rice forms, and then we have some answers on the top. Yeah, well, how good our audience do. Are they in the right track? Yes. It's livestock. Yeah, so that's correct. And when you look at methane, it has many different sources. So this same list as you answered the question for part of them are natural like wetlands. And most of the fires, but a lot of them are also anthropogenic. And that is one of the things where they focus on now also in the last COP28 this for methane, at least that focus for methane was to reduce the end of the dealing sources and to have an agreement on that. So one of the things we did with topomi is to start to look at oil and gas. And we first on the left hand, you see that we first looked at large lakes. So we are looking here at Turkmenistan. And you see three images one in December to in January. And the last one in January has a big red block. So this here on the left hand side, it's that image. That was a big leak of an oil and gas exploration. And we were able to measure that from space. I mean, the oil and gas exploration was informed and the leak was shut. It's a very remote area. Normally, oil and gas industry knows what's going on. But this is extremely remote area. And therefore, there was no one apparently present at that point in time. On the right, you see what we call regular operations. So we're looking at the premium here, the largest oil and gas fields in the United States. So regular operation means we can look at leak of methane. So everything we cannot get, we lose in the exploration. That's what we are measuring here. And you see that you measure methane and also NO2. And what is special about this is that it's only one day you see 31st of January 2019. And with the previous instrument from Europe's key monkey, we had to efforts over a year to see any methane over this area. And now one day measurement, it's not one day measurement, it is one measurement. Because once around 130 over this area. And the integration time of this instrument is one to two seconds. And that's what we measure here. So that's really, really a big, big, it's a game change basically in our capability to measure methane from space. So on top of that, we have new developments. We have small sets. It's huge development in the satellite business. And one of the small sets is called GHD set. It's measuring only methane, not also all the other trace cases tropomy measures only methane, very high spatial resolution, but no daily global coverage whatsoever. But we can combine these measurements. So we use tropomy, we see this large leak, for example, in Turkmelystam on the right again. And then this small set, you can direct. So you know where the leak is, you fly over with a small set, you direct it to that leak, and you can also follow it. So you can integrate for a long time. And with that, you can get detailed observations of methane. And this combination will be used for this methane pledge, not the only thing, but will be used to see if we are effective in reducing our methane sources. Okay, so I come to my last item is Africa. So why would we like to measure over Africa? One of the main reasons is that we expect a huge population grow in Africa. So we expect almost more than tripling from now 1.1 billion people to 3.8 in 70 years from now 70. I think that is never, never shown before. At the same time, there's an industrial revolution going on in Africa, so that will already lead to more pollution. And that combination will lead to huge amount of pollution, pollution and greenhouse gases. And it's important to measure that and to be aware of that. So you see on the left, you see measurements from topomi. You see that Africa has all pollution sources. So we have fossil fuel, which we can see in nitrogen dioxide on the left up. Then next to that, you see carbon monoxide released by biomass burning, wildfire, agriculture burning. On the lower left, you see biogenic emissions. These are emissions from forest, mainly in formaldehyde, one of the pollutants we can measure. And on the right, you see also index or also from Sahara dust. And at the same time, we can measure this with topomi, but we barely have ground base measurements in Africa. And there's also a lack of emission estimates over Africa. We don't have the information. And we need emission estimates to do a proper calculation. If we don't know what's emitted, we cannot calculate the chemistry. So there is an urgent need for a new capability for air quality management for Africa. So I will go a little bit deeper into this now. So this is an image from the Washington Post showing you the 100 largest mega cities in 2025, and they are mainly in Asia. This is the prediction. So in 2100, this will be shifted to Africa. And the largest, 10 largest mega cities will be in Africa by that time. That's what is the expectation. Here you see count base measurements. On the left, you see them for ozone and on right for aerosols. And you see that most of these count based measurements are in the Northern Hemisphere, Europe, US, Asia. There's barely anything in the global south and also not in Africa. So it means that there is one count based instrument per country. Africa is a continent per country in Africa. That's a completely different ballpark in the Netherlands. For this type of measurements, we have 60 of these count based very accurate monitors. And then we have more or more less accurate. So that's a big issue because we have to satellite crossing once a day, but that's basically the information you have. And the count based instrument, of course, can measure all the time. So you have also, you have really a time evolution over the day. It gives you other information that you really need. And it measures on the ground where we breathe. But it's not easy to build that kind of count based systems. It really takes a lot of effort. So at the same time, Africa is just like the other continent. So they also had COVID. You look here at Nigeria, nitrogen dioxide again on the left. It's April 2019. On the right, it's 2020. You see clear decrease in nitrogen dioxide. There are also big differences. And one of the main things is the biomass burning. Biomass burning, since it's an agriculture practice in Africa is really huge. And shifts over the country from April to June to October shifts from north to south. You see that in the carbon monoxide and in the end of two measurements. So that means there are more different emissions in Africa than in other continents that also from a research point of view, this is really, really interesting. There will be other chemistry going on. And so we would like to know more about it. So one of the things we started to do here in this lab in NCAR is to use the topomi data to look at mining activities, metal mining activities. And we were initiated by that by a New York Times article, 2021, talking about the clean energy revolution and the metals we need for that for batteries, basically. So you see that cobalt is mainly from Africa. So we thought, well, can we see that in the satellite data? Why would we see that? We don't measure cobalt. But you use machinery to get this cobalt out. And this machinery is run on diesel and diesel that will produce a fossil fuel nitrogen dioxide. So what you see there on the right is an image which was used in this photo, which was used in this paper, the New York Times article, you see a city on the left. You see a huge mine on the right. It's a copper cobalt mine. The mine is as large as the city. So we started to look in the topomi data. Can we see that in our data, this nitrogen dioxide? And can we see it's from the mine and not from the city? And we turned out to be able to see that. So the large and the two blob we found was from the mine. So we looked at six mines in that area, and we calculated the emission, which I explained to you with a bloom and back into the pipe. And we combined that emission calculation with production of that mine, which we could find on the internet. So how much copper do they produce? And is there a correlation? And there is a strong correlation. So that's what we showed. And it's the first time that this type of calculation is done based on satellite data. So one of the things we are now advocating for from NCAR, UCAR, and we work with a very large community, national international community for that, is to have also geostationary satellites over the global south. So what you see here is the global atmosphere chemistry constellation. It's all the satellites, Europe, US, Asia. On the lower bar, you see all the polar satellites. So they fly from pole to pole. A central 5P, the one on the left is the one with Torobomi. But you see that we also launched geostationary satellites, the one over Asia is already there, GEMS. The one over United States was launched this year, Tempo, and the one over Europe will be launched this year or next year. But you also see that we have no plans for the global south whatsoever. And that's one of the things we are now starting to advocate for to get satellites there. So when you would have a satellite like that, let's see if we can get this working. Yeah. So this is the one over Asia. You have about every hour, you have a measurement during the day because we need the sun so at night we cannot measure. So that means that you really have a lot more measurements over Africa or South America and when you would have a geostationary satellite. So let's see if we can get out of the slide. Yeah. So we are working. We think that we need to set two geos over Africa's huge continent. One can measure Middle East and the northern part of Africa and the other one the middle part and the southern part. And so we initiate this, we work with scientists in the US, the United States and Europe, but the first thing we now are doing is trying to reach out to scientists in Africa. Because we really want to do this with the scientists in Africa for many, many reasons. One of the reasons is that with Topomi, my experience is that it's really difficult to interpret the data if you do not work with the people living in that specific country because it has such a high spatial resolution, you really need to know what's going on on the ground to understand what you see with the satellite instrument. Yeah, this was my last slide. So I hope that I convince you that the only on top of me instruments led to new findings in the air quality domain that we have new capability also for greenhouse gases, especially methane. It's important for COP 28. And we are building this air quality constellation and we need to add the global south to that. And I hope that you also convince that emission regulation, so the Montreal Protocol and the movie of Obama is effective. So when we control our emissions, we can be effective and we can measure that from space. About a hand for this great talk. And let's open the floor for questions. If you have a question in the audience, raise your hand. Welcome. Can I get here? Do we have questions in the audience first? PhD over here. Okay, if we don't, we have one. Okay, cool. I have a question on on it's kind of mechanics of the thing, but you said you download gigabytes of data per day. So I think you only have about two opportunities per orbit to download data. Is that right? So you don't have any issues? I mean, you have a couple of stations, one station near, I don't know, Norway and down, down in Antarctica to download data? Yeah, so usually for the polar satellites, you need two count stations on average. And there are located near the poles because there is broad band stage overlap. So you can basically download with one of the one is in Kuna, I believe, you can download 10 of the 14 orbits. And then and then they pushed you data down in during the crossing of about 10 minutes, you can receive the data. And so that works fairly consistently without any issues that that data rate? Yeah, yeah, yeah. We have an online question about data as well, which is, are the data these satellites collecting publicly available? Yes, I didn't tell that. But yes, they are. So only only data is public available via NASA. And the top only data is public available via the EU and ESA Copernicus sites and they are available. Most of the products are available within three hours of the measurement, with the exception of methane because that retrieval is complicated and takes more time. Any questions from the room before I move on to an online question. So we have a question from Edward, who said, you can use our light sources for spectroscopy from earth, but can you use the sun, the moon or other satellites as light sources? Well, in this case, we use the sun, you can also use the thermal infrared thermal radiation from the earth. So there are thermal infrared measurements will also measure air pollution, but not the type I talked about. We also have satellite measurements, which basically use the moon or even stars as a light source. And but when you, for example, use stars, then, of course, you measure the higher part of the atmosphere, you cannot really measure what's going on on ground, but you can measure 20 kilometers up to 80 kilometers altitude. So are there any satellites in orbit that use on orbit light source like laser to look down to the ground and look at sort of tomography? Yes. Yeah, yeah. So we have several lighters. They are usually used till now for clouds and and also also first suit to a meteor and a French development to do to use lighters for that. But one very famous one is Calypso. It's a French US collaboration. It's it's flying. It flew. It stopped now in the same and not far from the only satellite. So we had a whole train of satellites passing one spot on earth within 10 minutes or something like that. And Calypso was part of that. And that measured aerosol. So you but when you have that, you can really measure the aerosol vertical information. So you know exactly what altitude the aerosols are or the clouds. So it's used for that. But it's with that you don't have data cover coverage. I'm going to ask Pedro's question. He is writing to us from Mexico and he wants to know if there are seminars or events where people can learn how to use this data. Very good question. It's one of one of my ambitions here at this Institute to to to get a series developed so that people can really use the data and know how to use it. Because that is you need quite some knowledge to really use it effectively and correctly. It's not easy. I know that humans that has courses and how to use this data, but they are usually directed at scientists scientists level. And I'm not sure to what extent they are. They are open, but I'm not sure how well that is is outcast that people can find it. Let's go with question and data reporting. Will you be reporting to policymakers in order to inform future policy? Not for the for the ocean hole. That's formally we do that formally. So every year there's a meeting. They use the only the top only the grown the OMS all the satellite data we have. And they are used to assess if the Montreal protocol is still effective if the ocean layer is recovering if you see that recovering continuing. So that's a formal process. But for air quality and greenhouse gases, I think it might start now for methane. But it's not not formally accepted yet because methane and all the other trace gases the formal requirements for how much you may have is connected to calm based measurements. All of the questions are online today. So we have another question online that's one from Bernadette and she wants to know if all trace gases are concerning and as a follow up, why is nitrogen dioxide so important? If all trace gases are concerning, that's a tricky question. Well, let's let's say oxygen. You could also use a trace gas is something we need. So yeah, I'm not sure if everything is concerning in that aspect. You too is not directly toxic, for example, but it is the strongest greenhouse gas. And yeah, it's important because it has a huge, huge impact on climate change. And it's it's still the most important trace gas we should try to, yeah, minimize to cope with climate change. The challenge with CO2 is that there are many challenges. What one is that it's lifetime is so long, it's hundreds of years. So if you would stop all CO2 emissions now, then still that effect you will only notice generations from from here. When you reduce methane, we have effect in 10 years. So it doesn't mean that you should not reduce CO2. We have to do it. But we also should look a little bit broader so that we have some compensation in years to come. Our last question on mine. Can you comment on the need for geostationary measuring satellites over South America in addition to South Africa to Africa? Yeah, well, that is that's on our list. So we first want to try to get them over Africa. And it's that will be a long advocacy process. But also South America is on our list to get the geostationary satellite over and Australia would also be good. But the population increase in South America is from different order than in Africa. And that's why we we have our first priority for Africa. Are there any more questions in the room? Peter, now do you have any advice for aspiring scientists in the audience on how to have such a successful career in the sciences? Stole my question. Well, work hard. Yeah, I think one of the most to catch whatever successful career. The most important for that is that you're really, really interested in what you do. Because it will take a lot of hours. That that's the bottom line. And when you look at my work fields, my my lab at KMI, for example, but also lab here. There are all kinds of people that with different backgrounds. We have metamacist, mathematicians, we have chemists, we have physicists, we have museologists, we have geoscience experts, you know, and all of that with all the different backgrounds, you can work in this field. So it's not like you have to have only one choice at university or whatever. And then you can you have to do aerospace engineering, for some, but it's not a requirement. I didn't do it. I studied chemistry and then physics. And I end up in this field. So it's it's a very broad field to some extent, broadly receiving scientists from all capacity. But the most two important things I think is usually to really be interested and only then you can you have the stamina to work a lot. If there are no more questions, let's go ahead and give Dr. Peter Nelovell another round of applause for that excellent talk. And with that, I'm going to go through the message at the end. Thank you all again for attending this incredible lecture on air quality as a chemist. I have never felt happier at a lecture as part of our Explorer series. I hope to see you all again on April 24th for our next event on the intricate relationship between climate and climbing routes. This is going to be a different event and it's very exciting for us. If you're interested in more Explorer series events, definitely check out our website for upcoming lectures and conversations, as well as to view recordings of past events, including the one from today. If you are 18 years of older, please take a moment to fill out our three to five minute anonymous survey to help us better understand the impact of the program and how we can improve our next event. The survey will close on Monday, February 12th. You can find a survey by scanning the QR code. You can also ask a staff member if you would like to use one of our tablets to take the survey. And with that, I hope to see you all next time. Have a great rest of your evening. Thank you so much for coming again. This was great.