U.S. Greenhouse Gas Center (US GHG) and Remote Detection Of Methane Emissions

0:00 Speaker 1: Powerful greenhouse gas. And scientists have tracked its growth in the atmosphere over the course of decades by making very precise measurements at a series of remote surface sites. That's what you see on the left-hand side of this plot. It's a time series from our colleagues at NOAA, which illustrates how methane concentrations have changed over the course of recent decades. You see that trajectory in upward concentrations of methane in And you also see that in the past decade, that rise is actually accelerating, which is causing additional concern for both scientists and policymakers.

0:33 Speaker 1: Now, it's important to understand how methane contributes to warming, and that's what you illustrated on the right-hand side. Even though methane is present in the atmosphere at much smaller concentrations than carbon dioxide, it's an incredibly powerful molecule at trapping heat. And that means that even though there might be about 200 times more carbon dioxide in the atmosphere than methane, methane is actually contributing as much as 16% of warming relative to the pre-industrial era. This is one reason why methane is such an important target for policymakers to be able to reduce emissions so that we can help to reduce the rate of warming in the atmosphere.

1:20 Speaker 1: So we know that methane is increasing in the atmosphere from surface sites. But one of the challenges that we have is those surface sites, which are mainly at remote places like Mauna Loa, Hawaii or the South Pole, don't always tell us why methane is increasing or all of the information that we need about the complex processes that contribute to methane emissions and removals. This slide illustrates an important effort by scientists around the world who bring together some of the most advanced models of methane from different perspectives to try to understand and illustrate how well we know the global budget of methane sources and sinks over recent decades.

2:01 Speaker 1: They use two different perspectives to bring together models. Some are using surface data information about the land surface or activity. We call those bottom-up estimates. And other perspectives are come from atmospheric concentrations themselves, those surface sites, or increasingly satellite data, which can help us understand from an atmospheric perspective the budget of sources and sinks. And so this slide just illustrates some of the major categories of emissions that are contributing to methane concentration rises and warming.

2:34 Speaker 1: And this is a complex mix of both human-caused emissions and natural sources like wetlands. For human cost emissions, the main sources are from fossil fuel production and use, things like oil and natural gas production, and agriculture emissions, both from animals and from soils and from things like rice paddies. On the natural side, we see about 30% of the greenhouse gas budget for methane is coming from wetlands. And so that's incredibly important for us to track and understand how natural systems and how we manage them is changing the balance of methane in the atmosphere.

3:15 Speaker 1: One thing to note is that while we have an estimate of these different sources and things, There's a lot of uncertainty in some of the components, and that makes it very difficult for policymakers to track and identify whether we're making the right emissions targets. It also makes it difficult for scientists like me to predict how methane concentrations are going to change over coming decades and over the next century. That's particularly challenging because some of the emissions of methane from sources like wetlands are temperature sensitive, which means a warming planet actually means more methane being emitted.

3:53 Speaker 1: So understanding using a combination of satellites and models how these different sources are contributing and how those changes are manifesting in the atmosphere over time is important for all of us in terms of setting realistic emissions targets and making sure that we can predict how greenhouse gases will decrease in coming years with action. This last slide showing why methane is so important right now illustrates the policy imperative that governments around the world are placing on limiting methane emissions.

4:28 Speaker 1: At COP26 in 2021 in Glasgow, the world announced the Global Methane Pledge, which is a partnership of 158 countries around the world who are pledging to reduce emissions of methane to limit the rate of rise in concentration and thus their contribution to warming by 2030. And this is one reason that having good quality satellite information is so important for policymakers. We as scientists need to be able to help policymakers document that the changes that they've made in policy in reducing emissions are effective so that we can track that transparently and show that information to the world.

5:09 Speaker 1: With the next set of slides, we're going to introduce you to an exciting new initiative in the U.S. called the Greenhouse Gas Center. So you might be asking yourself, what is the U.S. Greenhouse Gas Center, if you've never heard of that before.

5:24 Speaker 2: The U.S.

5:25 Speaker 1: Greenhouse Gas Center is part of an ambitious national strategy to advance integrated greenhouse gas monitoring and information system. This is actually part of a report. You can track this back and actually read this full strategy online. There's a number of prototype projects to illustrate the efficacy of greenhouse gas monitoring. But within that, one of the central flagship projects is the U.S. Greenhouse Gas Center, which is led in a partnership by NASA, the Environmental Protection Agency, the National Institute of Standards and Technology, and the National Oceanic and Atmospheric Administration.

6:02 Speaker 1: And it's charged with facilitating coordination across both federal and non-federal domestic and international entities to integrate and enhance greenhouse gas data and modeling capabilities from the US government and non-US government sources for scalable impact. So what does that actually mean in real world terms? Scalable impact means we want to make data that is useful to people and supports decision making. Facilitating coordination means that the Greenhouse Gas Center is more than a website.

6:33 Speaker 1: It's actually working to improve the quality and reliability of information about greenhouse gases. And integrating and enhancing greenhouse gas data and modeling capabilities means that we're working across this complex array of very capable federal agencies to bring people the consensus information that they increasingly need to make good decisions on behalf of all of us. Now, within the US, the Greenhouse Gas Center is one illustration of a new type of project that's really designed to make science that's more responsive to public needs.

7:05 Speaker 1: So this is an example of a pyramid that shows, if we work from the bottom, how Earth observations and foundational knowledge of the planet is collected by NASA and other federal agencies. is coordinated into model estimates that can bring together different types of satellite information. We can distribute that in the second from the top layer of the pyramid to the public in lots of different ways to enable them to make better decisions over all kinds of variable things like water quality, fire management, air quality, and greenhouse gases.

7:43 Speaker 1: And then we can communicate to the public in that top level the work that we're doing so that they understand and have trust in the way that science is informing decision making. And at the very top, we're working increasingly within NASA and other federal agencies to make sure that our concerns and our research is not just motivated by scientific curiosity, but out of a real need that society has to be able to navigate a changing planet. So there's many versions of this pyramid, depending on whether you're studying water quality, air quality, or some of these other variables.

8:18 Speaker 1: For greenhouse gases, this also illustrates a lot of the ways that we're approaching activities and coordination within the center. So at the bottom level of the pyramid, we're doing things like coordinating and evaluating satellite data, working across ground networks to make sure that we have better standards that help us have confidence in those data sets. and expanding airborne measurements and coordination to complement places where we need additional information or to be able to show that the satellite data are of the highest quality.

8:50 Speaker 1: The next level up from the bottom, we're taking all of those data sets that we collect. We're working to incorporate those into models to be able to create more operational greenhouse gas products, which complement the kinds of data products we've provided for air quality or weather prediction for many, many years. We're working also to standardize how we evaluate models and develop new methods for integrating them so that we can give a more consistent answer to the general public. When we get to that second to the top level of the pyramid, we're working on setting up a number of services to engage with stakeholder communities and to serve them.

9:31 Speaker 1: not just through conversations, but to be able to deliver new tools, including an integrated greenhouse gas center data portal, so that they can access data more readily and understand the types of data that they're seeing with much more clarity than we've had in the past. And at the very top of that pyramid, we're working on highlighting all of this work through exciting new public outreach and education initiatives, including saying, like the Earth Information Center, which has helped us increase the visibility of many of these data products in places like the Smithsonian Museum of Natural History in Washington, D.C.

10:11 Speaker 1: So people can come and experience and understand the planet in a whole new way, the way that scientists have gotten to do for many, many years. And as we talk about the center, there are many sort of cross-cutting themes, but really focused on alignment with a variety of stakeholders who need good quality greenhouse gas information, working across the agencies and federal partners, and making use of open science principles so that people can have maximum confidence in the data that they see from the Greenhouse Gas Center.

10:44 Speaker 1: And to illustrate why we need to do this across agencies, There's a lot of words on this slide, and I don't expect anyone to read it, especially people who might not be familiar with U.S. government agencies. But this is illustrating that in the U.S., and in a lot of countries, you have different parts of the federal government doing really, really important foundational work that's not always connected. So each agency that's a partner with the Greenhouse Gas Center probably could make its own version of this pyramid.

11:13 Speaker 1: We all make our own observations. We have our own models that integrate those, and we have our own sets of websites and tools that help get the data out to the general public and stakeholders. And there's good reasons that we have different types of focus. NASA is a research organization. We tend to focus on airborne and space observations. It's in the name. So you can see a lot of focus there on developing and demonstrating new types of innovative satellite measurements. And that drives a lot of how we communicate to the public and how we motivate the models that we use, which are really grounded in those satellite observations.

11:50 Speaker 1: An organization like the Environmental Protection Agency, which in the U.S. is the entity that prepares the greenhouse gas inventory and works to make sure that that's communicated both nationally and internationally, works on a lot of detailed measurements that help us track emissions from things like stacks and ground-based stations. They have models that help track things like air quality exposure, which are the mandate at the EPA. So very different from an organization like NASA. And what we're trying to do through the Greenhouse Gas Center is really work across some of those silos and bring together the best of all of those tools across the federal government so that we can deliver information that is consistent and speaks with one voice to help serve stakeholders and the general public in a new way.

12:42 Speaker 1: So the U.S. Greenhouse Gas Center started and was motivated by three different types of use cases of really trying to collect and understand information about greenhouse gases at three different spatial scales and sectoral approaches. The first of those is improving availability of information of gridded anthropogenic emissions. That includes things like EPA's gridded methane emissions inventory over the United States. We are also working to understand and improve the quality of information on natural greenhouse gas sources and things like wetlands.

13:21 Speaker 1: And most relevant to this training to increase the availability of data from exciting new observations so that we can better track large emission events of methane and hopefully use those data sets to mitigate emissions and help slow the rise of methane concentrations in the atmosphere. And in communicating some of those data sets, we're really excited to be able to share with you our data portal, which is growing all of the time. So you'll see here links to get to the Greenhouse Gas Center webpage.

13:57 Speaker 1: In addition to the beautiful main page, we've got a lot of content under the hood. So if you look at data stories, you're going to find several in there that are focused on methane and explain in a lot more detail some of the observations that you're going to hear talked about throughout the training today. So I'll highlight one, tracking methane plumes from space and sky, which goes into a lot more granular detail of some of the remote sensing approaches from both satellites and aircraft. And there's this exciting tool that's growing all the time, which highlights all of the detections of these large methane emissions events that are detected from the emit sensor on the International Space Station.

14:38 Speaker 1: So this is a tool that we're actively developing and soliciting feedback from stakeholders, and we'd love your feedback as well. You can share that with us through the Greenhouse Gas Center data portal so that we can make this better and more useful all the time. So please, we invite you to go join us at the Greenhouse Gas Center data portal, learn more, share with us what you think, and thank you very much for being here. I'm very excited now to hand this off to Andrew so that he can tell you in more detail about some of the approaches we're using to improve the availability of remote sensing data to help track emissions of some of these very, very important sources.

15:21 Speaker 2: Great. Well, thank you, Leslie. My name is Andrew Thorpe.

15:24 Speaker 3: I'm at the Jet Propulsion Laboratory, and I will be discussing the next section on satellite.

15:28 Speaker 2: Observations of methane. There are a whole.

15:34 Speaker 3: Suite of technologies that are currently being used to detect point sources of methane. These can include in situ measurements as well as remote sensing measurements. But I think it's first important to talk about what is a methane point source. And you can see an example in this cartoon of a methane emission from a distinct location on the ground. And these types of emissions can come from different emission sectors, things like oil and gas emissions, from landfills, agriculture activities can all generate these point sources.

16:08 Speaker 3: The in-situ measurements as shown on the left there are directly measuring the air methane concentrations. And these types of instruments can be put in different types of payloads and things like towers, driving surveys. They can be put into drones that can fly around and measure the atmospheric concentrations of methane. Around a point source, aircrafts can also measure methane concentrations as well. For remote sensing technologies, if we start with ground-based technologies, there are camera systems that remotely sense methane and can provide imagery of methane plumes.

16:48 Speaker 3: And there's also aircraft instruments, both passive and active instruments, that can remotely sense greenhouse gas absorption features. And finally, there are satellite measurements, and that is really the focus of this presentation. There are a number of different instruments that are currently measuring methane emissions from space, and these can be categorized into two different groupings. There are the area flux mappers, as shown on the upper panel of this figure, as well as the point source imagers.

17:21 Speaker 3: And I'll be giving and highlighting an overview of some of the strengths and weaknesses of these types of instrument systems. If you're interested in learning more about this whole suite of instruments, I would I'll refer you to this CEOS webpage that does a very nice job of outlining all of these satellite capabilities with specific information about how they were designed and what they're focusing on, what types of gas species, including methane. So the area flux mappers are all shown in the upper panel of this figure, and I'll be focusing on both GOESAT and TRAPOMI, two of the more recent missions that are measuring methane globally.

18:06 Speaker 3: Both of these instruments have coarse spatial resolutions. That means that their image pixels are on the order of kilometers in scale. And because of this, they're really best suited for mapping global methane gradients and not point source observations. The example in the lower left for GOSAT2 has a 10 and a half diameter wide image footprint. And this provides, over time, a nice visualization of methane gradients globally, as you can see in this image. We've got some hotspots, for example, in parts of China, as parts of the middle part of the United States, as an example.

18:48 Speaker 3: But you can also see that there are some data gaps in this record, so it's not getting full coverage. And it takes quite a long time to get a full coverage of these areas, given it's only measuring one location at a time. Trapomi, in contrast, has a smaller spatial resolution. So that's five and a half by three and a half kilometer wide image pixels. And it has a very wide image swath. So it allows it to perform global mapping every day, which is pretty remarkable. And this is an image from a recent paper that shows those methane gradients, which are very nuanced across the globe.

19:28 Speaker 3: And again, you can see that we've got basically full coverage globally.

19:33 Speaker 2: Every day, which is very powerful.

19:38 Speaker 3: Point source imagers, in contrast, have very fine spatial resolution.

19:42 Speaker 2: So we're talking.

19:44 Speaker 3: About meters scale for image pixels. And because of this, they're ideally suited to identify distinct methane point sources. And you can see the whole suite of these types of instruments. Most recently, instruments like PRISLA NMAP EMET and the Carbon Mapper Panager-1 satellite, which recently launched, are all doing this type of methane measurements. Did want to focus on two examples of some of these instruments, including GHGSat and NMAP. GHGSat is a private company that is providing methane plume imagery, like what I'm showing in the lower left here.

20:24 Speaker 3: It has a 30 by 30 meter image pixel, and it has a coverage of 12 kilometers by 12 kilometer scenes. What this allows is the identification of point sources in a scene and ultimately in a mission quantification that's associated with this example. We'll be talking a little bit about the quantification in subsequent slides. NMAP has similar spatial resolution, 30 meters by 30 meters. This has a wider image slot so we can cover a larger area, 30 kilometers across as it stands over the surface of the earth.

21:02 Speaker 3: And this is an example of two methane plumes that were observed in one scene from NMAP. So how do we actually measure these point sources with these remote sensing instruments? Well, one class of instrument using passive remote sensing uses the.

21:21 Speaker 2: Sun, where photons are.

21:26 Speaker 3: Passing through the atmosphere, hitting the ground, and being reflected up into our imaging spectrometer. Along this light path, there are absorptions in the shortwave infrared that our instruments can measure. And this principle applies not only to the NASA JPL imaging spectrometers, but to the other point source imagers that I discussed in the previous slides. So for instruments like EMET, the methane spectral fingerprint is shown here at the spectral resolution of the instrument. 7.4 nanometer spectral sampling.

22:03 Speaker 3: And you can see distinct absorption features that are present between 2,200 and 2,400 nanometers. And we have a nice fit between our measured values and some modeled results to give us further confidence that we are in fact observing methane in our measurements. For over a decade, we've been using airborne imaging spectrometers to enable future observations from space for instruments like EMET. We've been using AVERIS in the 2000s for the first demonstration of this capability and have been expanding this to the Global Airborne Observatory, the AVERIS Next Generation Instrument, and most recently the AVERIS III Instrument.

22:49 Speaker 3: These allow us to map out methane point sources across different emission sectors, energy, waste, and agricultural emissions. And airborne instruments provide higher sensitivity and a lower detection limit relative to the satellite instruments, primarily because the image pixels are much smaller and you have less dilution of the greenhouse gas within an image pixel. So we typically think of instruments like AVERIS-3 of having a minimum detection limit of around 10 kilograms of methane per hour. And this will vary based on flight altitude and wind conditions, but This is a good sort of rule of thumb.

23:32 Speaker 3: In contrast, instruments like EMET are going to be less sensitive to methane emissions. These instruments, EMET has a sensitivity that's around a few hundreds of kilograms of methane per hour. And again, this varies based on things like wind condition and surface albedo. But one of the benefits of EMET is that it has a much wider coverage relative to the airborne instrument. That allows us to map out these emissions over larger areas. And now I'm going to be focusing on observations using EMET for methane point source detection.

24:16 Speaker 3: The Earth surface mineral dust source investigation includes an imaging spectrometer onboard the International Space Station that has an 80 kilometer wide image swath and a 60 meter spatial resolution, allowing us to identify methane emissions across different emission sectors. The figure on the right is from a recent paper that has highlighted some.

24:41 Speaker 2: Of those capabilities.

24:43 Speaker 3: And what's nice about this example is that this is a very complicated set of methane plumes from different emission sectors. If we focus on the large scale image there towards the north of the image, you can see a prominent methane plume from a landfill. And just to the south, there appears to be a wastewater treatment facility methane plume as well that is distinct. Towards the center of the image, we've got a possible natural gas leak from a pipeline, and you can see the pipeline location in gray there.

25:18 Speaker 3: And then all the way to the south in the image in the blue circle, you can see methane emissions from a power plant.

25:25 Speaker 2: And this is a natural gas fired power plant.

25:28 Speaker 3: So what's very nice about this one image from EMIT is that you can not only identify multiple emission sources, but you can attribute them to different emission sectors. And that's quite important to better understand where this methane is coming from. What's nice about EMIT is that we also have the capability of doing carbon dioxide emission retrievals. And you can see for that, power plant location. In the upper right, we have sort of a co-located and co-emitted methane and CO2 at that location.

26:01 Speaker 3: So this is sort of another exciting capability of EMET and something that we'll be looking at more going forward. So EMET methane observations can provide key information specifically by locating methane sources. In this overlay of EMET results on a higher resolution basemap image, we can take the methane plume away and you can start to see where these methane emissions are coming from as indicated by these white circles. The white circle on the top of the image is associated with a gas compressor station.

26:38 Speaker 3: And this is an area that we've seen lots of methane emissions from in the past and methane compressors in different countries have been known to leak methane, and we've observed them both with EMET and airborne campaigns in the United States with Averis Next Generation, Averis 3. And the example to the south of that white point is less clear, and what we think is going on there is that there's likely a buried natural gas pipeline at that location that is leaking, and you can see subtle evidence of that Just in the RGB image here, you can see sort of a line, a very faint line that's near this location.

27:20 Speaker 3: And this is another type of emission that we've seen repeatedly with both EMET and airborne instruments in California. So you can imagine sharing these results with people that are interested in using the results can be very powerful because it can lead to emission mitigation. And we have seen that over the years. and sharing the results with folks who are interested in the results can lead to folks following up with these emissions and ideally doing something about them. This is an overlay of all of the methane plumes that have been observed with EMET to date as published on the US Greenhouse Gas Center's web portal.

28:10 Speaker 3: And what's interesting is you can start to see that there are clusters of methane plumes in certain areas around the globe. So what we can do is we can compare emit methane plumes, which are referred to as top-down measurements from satellites, and compare these to bottom-up emissions inventories, like what I'm showing in the figure on the right for fossil fuel exploitation. The Permian Basin in the United States is known to be a significant methane emitter, the largest expected methane emissions in the United States.

28:50 Speaker 3: And you can see in the bottom-up inventory the expectation that we would have in methane emissions there. And in the EMET results, we do have a very high density of methane plumes at that location. In Turkmenistan, similarly, the bottom-up inventory shows expected methane emissions. And we're seeing a high density in the EMET methane plume locations. And then finally, for China, in this portion of China, we have coal methane emissions that are expected and have been calculated for the bottom-up inventory.

29:25 Speaker 3: And when we're looking at EMET results, we see that clustering of high density of these methane observations of methane plumes. What do the methane plumes look like at these locations?

29:42 Speaker 2: In the left from.

29:43 Speaker 3: The Permian Basin, you can see a small subset of the Permian, 100 by 100 square kilometers, a mixture of very large methane emissions and very small emissions. Some of these emissions are coming from gas compressor stations, Some are coming from individual well pads, from pieces of infrastructure like tanks or drilling rigs, things like that. In Turkmenistan, we've got an area of around 200 by 200 square kilometers. We know that Turkmenistan does emit significant methane emissions from these point sources based on a number of studies of these point source imaging systems, including EMET, but other instruments like GHGSAT and others have an end map and PRISMA.

30:32 Speaker 3: And they're really spectacular sets of methane blooms that are in many cases associated with pipelines that are associated with this part of Turkmenistan on.

30:42 Speaker 2: The western coast.

30:44 Speaker 3: The China coal methane emissions are shown for a small subset of the area here. And you can, again, see that the emissions are from different spatial scales. Some are very large and some are very small. But typically, these are associated with known pieces of infrastructure on the ground, specifically these coal mine ventilation shafts where they are getting sort of pumping out air to keep their workers safe, right, getting that air out of the mine. And that is an easy avenue for methane emissions to make it into the atmosphere where EMIC can observe them.

31:24 Speaker 3: We've been seeing emit methane emissions from the landfill sector. This animation shows a time series of methane plumes for a specific landfill in Jordan. This is a pretty spectacular set of methane plumes, all weather veining relative to the local wind conditions that change day to day, but the source of the emissions, the landfill remains consistent in this example. These methane plumes over time allow us to better understand emissions and their variability over time. And ultimately, if we are going to be estimating emission rates for these examples, it's really critical.

32:07 Speaker 2: To have more than just one observation.

32:10 Speaker 3: And we'll be talking a little bit more about emission quantification later on in this talk, but it is quite critical to have repeat mapping of these methane plumes over time I will say that of the landfills that we've seen with EMIT, it does appear that these emissions do appear to be persistent.

32:30 Speaker 2: They seem to be there all the time.

32:36 Speaker 3: This is another fascinating example from a different emission sector. This is from agriculture in the San Joaquin Valley in California. And what's notable about this example is that this is representing more of an area source enhancement relative than a.

32:53 Speaker 2: Point source observation.

32:54 Speaker 3: And what we think is happening here is that we are seeing sort of the combined inputs of a number of point sources in the area and a regional enhancement.

33:05 Speaker 2: That's associated with the agriculture in the area.

33:08 Speaker 3: And in aggregate, we're able to see that enhancement as manifested as the sort of area-wide enhancement. So I did want to just highlight that example because I think it's a very exciting example that we're going to be looking at in more detail going forward. Even method emissions can be unexpected and provide actionable information. These two examples are good examples of methane plumes that we shared with stakeholders and that led to some follow-up. The example on the left is a methane plume in Kansas.

33:49 Speaker 3: And this is the largest methane plume that was observed in the United States. And I was surprised to see an example.

33:56 Speaker 2: Like this in Kansas.

33:58 Speaker 3: That was one of the reasons that we followed up with the EPA and shared this result, the information about the emission location, the methane plume itself, the time that it was observed. And the EPA was able to follow up and confirm that there was a pipeline issue at this location that required a repair and explaining why there was a methane emission at that location. The example on the right is a methane plume over water in the Gulf of Mexico. It's very difficult to observe methane plumes over water with EMET because we can't point the instrument and we can't optimize for sun glint.

34:41 Speaker 3: The water is very dark in the areas of the footwave infrared where we do our methane retrievals, but we did just have enough glint in our scene here to see this methane plume. It was a bit unexpected to me. We shared these results with our NOAA colleagues, and the rig source was verified and confirmed and verified by also other measurements from different satellite instruments.

35:12 Speaker 2: It's important to.

35:13 Speaker 3: Understand EMET's satellite coverage, and this is what I am showing in.

35:18 Speaker 2: Blue in this figure.

35:19 Speaker 3: You can see that there is a latitudinal cutoff, and that's dictated by the orbit of EMET on the International Space Station. So we are just not getting observations at high latitudes. Why is this important? Well, if you look at the distribution of methane point sources alone, you can see that we have no methane plumes observed at high latitudes. And it's quite important to know that we also do not have observations from EMET in those high latitudes. So that's just a caveat and something that is important to note with any instrument system.

35:59 Speaker 3: You need to know where you've had observations, where you've seen methane plumes, and if there are areas where you're not seeing methane plumes, Can that be explained because you just don't have measurements in those areas? So in some of the previous slides, I talked a little bit about methane enhancement observations with EMET. We are making these level 2b methane enhancement maps available through.

36:30 Speaker 2: The LP DAC, and you can see an example of that.

36:34 Speaker 3: This is generated for an entire EMET observation or granule, 80 kilometers wide in this example. And there are a number of these that are sort of stitched together to make a cohesive image, but these are delivered sort of granule by granule. Within that methane enhancement map, there's actually a small methane point source that is hard to see.

37:01 Speaker 2: In this slide.

37:02 Speaker 3: But you can clearly see it in the other level 2B data product, this methane plume image, which is also delivered as a standalone data product. The methane plume images are made available also through the U.S. Greenhouse Gas Center web portal and the EMET Visions web portal as well, and that will be discussed in part two of this training. We're also making full-scene CO2 enhancement maps available, as well as the CO2 delineated plumes for the level 2b data product as well. Those are also available through the LP DAC.

37:43 Speaker 3: And we're currently working on emission quantification, both for methane and CO2. So these aren't yet available, but will be made available also through the LP DAC. We also have AVERIS data, the airborne version of EMET. And this data is flowing to the Oak Ridge National Laboratory, ORNLDAC, and you can check out that using this link. And I did want to emphasize that all of our results are open source. The data is open and our code bases are also publicly available so anyone can replicate any of our data products.

38:23 Speaker 3: I did want to talk a little bit about emission estimates. And these are generated using our methane enhancement maps, which represent methane enhancements above backgrounds per pixel within the scene. The methane plume of interest is shown in the area in the red box there. And you can see that we have delineated that methane plume. And we're delivering that as a methane level to be data product. We can then use that delineated methane plume to calculate an emission rate. And we do that using the equation that's shown in the upper right here, where the emission rate in kilograms per hour is derived by first calculating an integrated mass enhancement in the units of kilograms.

39:16 Speaker 3: And that's basically summing up all of the methane present within that methane plume in terms of.

39:23 Speaker 2: Kilograms of methane.

39:25 Speaker 3: We then can multiply that by wind speed and divide it by a plume length to estimate that emission rate in kilograms per hour. So once you have an emission rate, there's the obvious question of, is it correct? And so one of the ways that we've been validating our emission rate calculation methodologies is using methane control releases, where you have a known methane release on the ground. In this example that I'm showing in the figure in the lower right, we're using aircraft instrument average next generation.

39:59 Speaker 3: We are flying the area and we're using this method to estimate emission rates.

40:04 Speaker 2: And then we're.

40:05 Speaker 3: Comparing our derived emission rates with the known values, which are shown in the figure in the lower right at 47.5 kilograms and 101.7 kilograms. Those are those horizontal gray lines.

40:18 Speaker 3: So these types of controlled release experiments allow us to validate this approach. So what's the importance of these large methane emission events to methane emissions more broadly? We know that large point sources are responsible for the majority of observed airborne methane emissions from campaigns with adverse next generation. And you can see that demonstrated in this figure on the left, where on the x-axis, we've got the distribution of point source emissions in terms of kilograms per hour.

40:56 Speaker 3: At 100 kilograms an hour, if you follow that dashed line upward, it intersects the blue and the red lines at a percentage on the order of 80 to 90%. So that indicates that methane emissions that are above 100 kilograms per hour are really disproportionate in their contribution to the observed methane plumes in the area. And that means that there's a small number of emissions that you can identify, share with folks, and potentially mitigate. We also know that from other airborne surveys, like this AVERIS NextGen and Global Airborne Observatory campaign, that the point source emissions represent a significant contribution of the total regional fluxes of the area.

41:44 Speaker 3: and this is on average around 40%. So what I'm showing in this image shows regional total methane flux values as defined by the Kripomi satellite in blue, and that represents the basin scale total emissions of methane, including the point source contribution, but they're all sort of aggregated together. And then if you look at the red bars, you can see that for a number of different airborne flight campaigns in the United States, you can see that the point source contribution is significantly lower than the regional total.

42:23 Speaker 2: Methane flux for that specific area.

42:27 Speaker 3: So this again indicates that point sources are important relative to these basin scale emission estimates. And again, it offers the potential for follow-up and mitigation. NASA's Open Source Science Initiative has expanded the use of EMET data over the last few years. And these are a few stakeholders that have indicated an intent to use EMET data or exploring this capability, both EMET radiance data, methane observations, and other aspects of the EMET mission. And this is very exciting to see the expanded use of EMET going forward.

43:15 Speaker 3: So these satellite observations of large emission events do have strengths and weaknesses, and I did want to highlight.

43:21 Speaker 2: A few of these here.

43:23 Speaker 3: One of the first strengths is these technologies are really capable in their ability to observe point source emissions and identify the location of the emission sources. They allow for quantification and attribution of the emissions to different sectors, be it oil and gas, agriculture, or waste, as an example. These mapping capabilities lead to improved understanding of anthropogenic emissions, and that's really quite an exciting capability. And finally, making these results publicly available can inform mitigation strategies.

43:59 Speaker 3: So many of these methane emissions are pretty unexpected or have been unexpected in the past, and by providing these results and making them publicly available, people can start to think intelligently about Why are we seeing methane emissions where we are? Are there opportunities to reduce these types of methane emissions? On the flip side, there are limitations. These technologies can only observe large methane point sources, not very, very small emissions. So we have to be clear about that. The individual instruments have limited spatial coverage and temporal revisit.

44:37 Speaker 3: Talked a little bit about that with EMET, with the ISS orbit not getting to high latitudes as an example. So that's something that that you need to be aware of when you're looking at any type of point source imaging system. Then finally, an observation reflects only a snapshot in time, and repeat observations are required to better understand if the emissions are intermittent, that is to say, if we only see them sometimes, or if they're always there, if they're persistent.

45:11 Speaker 3: So with that, I'd like to hand this off to Melanie, who's going to summarize this training.

45:21 Speaker 4: Thanks, Andrew. Let's take a minute to review some of the key points from part one of our training. Methane is a potent greenhouse gas, and scientists have observed its growth in the atmosphere over recent decades. Scientists have additionally observed that this increase has accelerated in recent years. Despite the fact that CO2, or carbon dioxide, is about 200 times more abundant in the atmosphere than methane, methane still contributes as much as 16% of warming relative to the pre-industrial era.

45:55 Speaker 4: So it's an important target for policymakers to reduce emissions to reduce this rate of warming. Despite the fact that observations clearly show an increase in methane concentrations, more measurements are needed to understand the sources and sinks of methane to understand how effective mitigation strategies will be. And satellite observations are a key part of showing the effectiveness of policy changes. We learned that the U.S. Greenhouse Gas Center, led by NASA, EPA, NIST, and NOAA, are part of a national strategy to advance an integrated greenhouse gas measurement, monitoring, and information system.

46:37 Speaker 4: The goals of the U.S. Greenhouse Gas Center involve making data that supports decision making, improving the quality and reliability of information, and ultimately providing users with consensus information to enable climate change mitigation. We were also introduced to the U.S. Greenhouse Gas Center portal, which contains data stories, explanations of available data, alongside visualization tools. We'll learn more and see a demonstration of this portal in part two of this training. Point source observations of methane can be made using in situ or remotely sensed measurements.

47:22 Speaker 4: Satellite observations have less sensitivity than airborne observations, but satellite observations have wider spatial coverage. There are two primary types of satellite sensors that measure methane, area flux mappers and point source imagers. Area flux mappers have coarser spatial resolution on the order of 3.5 to 10.5 kilometers using the examples that were shown here today. These are best suited for mapping global methane gradients. Point source imagers have finer spatial resolution on the order of about 30 meters using the example shown here.

47:59 Speaker 4: and are best suited to identify distinct methane point sources. Point sources are emissions of methane from a distinct location on the ground and can come from different emission sectors such as oil and gas, landfills, or agricultural activities. The emit sensor onboard the International Space Station is a point source imager with 60 meter spatial resolution. Because of the orbit of the ISS, IMIT cannot observe methane plumes at high latitudes. IMIT methane observations can be used to locate methane sources associated with known pieces of infrastructure, which can lead to mitigation activities, discover unexpected or unexpected emission sources not in inventories such as pipeline leaks or new sources, or track methane point source emissions over time.

48:59 Speaker 4: we learned that emit data products include methane enhancement maps and methane plumes, where methane enhancements are enhancements of methane above the background of their scene. And future emit data products will include methane emission rates. In part two, we'll learn about several platforms that can be used to access or visualize EMIT observations, specifically the U.S. Greenhouse Gas Center portal, which we heard about earlier in this session, as well as the EMIT Visions portal and NASA Earth Data Search.

49:39 Speaker 4: Quick reminder, this training series will have one homework assignment. You can access the homework from the training webpage starting November 21st and answers should be submitted via Google form by December 5th. Certificates of completion will be issued to participants who attend both live trainings and submit the homework before that deadline. Certificates will be issued by email about two months after today's training. This slide shows the contact information for myself and today's speakers, as well as links to the RSET website, our YouTube channel and Twitter, or X, and our sister programs, Develop and Surveyor.

50:21 Speaker 4: Finally, here are some links to resources that were mentioned during today's training,

50:30 Speaker 4: as well as information for publications that were referenced in the slides you saw today. Thank you so much for joining us today. We'll now transition over to the question and answer portion of today's training. So we'll just take a minute for the questions to come up and we'll step through these one by one. Quick thank you again to our guest speakers. I'll read these questions out loud and I invite our guest experts to unmute and speak over some of the answers that have been written here. So first we'll start with question one.

51:16 Speaker 4: How are new point sources discovered? Does one work from area sources down to point sources or does one use other databases such as gas pipelines to nominate candidates?

51:31 Speaker 1: Great.

51:32 Speaker 3: So I'm happy to take that one. Can you hear me? Great, so this is a really great question. So in some cases we are using these global mappers to look at areas of the world that might be of interest and then doing some follow on analyses informed by EMIT results. But most typically what we're doing is we're actually just looking at all of the data that comes in as part of the EMIT mission. And we have a team of scientists that are looking at these results, identifying methane plumes. And we are then using additional information as part of our quality checks on this data before we publish these.

52:17 Speaker 3: And that includes using information like higher spatial resolution, true color imagery for context. I showed an example of that in the slides. And we also can use infrastructure databases in some examples to better understand what's going on.

52:33 Speaker 2: On the ground.

52:37 Speaker 1: Great, thank you.

52:39 Speaker 4: Question two, how are different types of sectors identified and attributed when they're located maybe in the same small area?

52:54 Speaker 3: I'm happy to take this one as well. So, I think slide 32 is a nice example, I think, to try to answer your question. So in that example, we had one snapshot from EMIT, right? And then in that snapshot, we had multiple methane plumes that were coming from different emission sources, right? So you might recall from that slide that there was a methane emission from a landfill. We also had methane from a power plant from the energy sector. We also had methane from a natural gas pipeline. also energy sector emission.

53:37 Speaker 3: And then we also had a smaller methane plume from a wastewater treatment facility. And so I think this is really the power of this technology is that you see a plume, and in most cases you can identify where that methane is coming from, and then you can tie it to an emission sector, which is a really, a capability that's pretty distinct with these types of technologies.

54:03 Speaker 4: Okay, question three. At what point in the end-to-end tasking collecting detection pipeline is wind data taken into account, either modeled or real-time? For example, is tasking suspended in fire wind periods, or is wind incorporated in some post-processing stage?

54:27 Speaker 1: Andrew, do you want me to take that one, or do you want.

54:28 Speaker 2: To take that one? Please. Leslie, thank you for offering.

54:30 Speaker 1: Yes, thanks. Sure. That's kind of in between our areas of expertise. So this is a really good question. Winds are incredibly important in terms of interpreting the data that we get from sensors like emit. But, you know, one thing we know at NASA, no satellite does it all. No satellite makes all of the observations.

54:46 Speaker 2: That we need.

54:47 Speaker 1: So a lot of times we're taking wind information from things like weather models or other sensors, maybe even in some cases aircraft observations in the area if they happen to be available. and using those to estimate emissions, which many stakeholders need to have more quantifiable information than just the concentrations that are detected immediately by emit. And it's important to note that the wind conditions, as the question is asking, they don't affect how we collect the data with an instrument like emit.

55:18 Speaker 1: They are coming into play in that post-processing and when Andrew and his team are providing those kinds of emissions estimates. One thing to note is that NASA and the whole EMIT team are really, really careful and dedicated to providing only the highest quality data possible. And so there are times where when we don't have high confidence of a plume detection or when we don't have high confidence of the emissions that are estimated because of environmental conditions like wind, we may not provide that data because we don't have the greatest confidence in the data quality.

55:53 Speaker 1: And there are some of these kinds of conditions that we can anticipate. For example, higher winds can make the detection of emissions more challenging because you have the emissions spreading over a larger area away from the source. And so that's really a place where we're bringing together all these different types of observations, but also in a lot of cases, bringing in, in some cases, additional resources like airplanes, like ground-based networks to really try to make sure that we can validate the data sets that we collect both directly from AMID and the emissions that we estimate and to have the utmost confidence in the quality of the data that we provide.

56:30 Speaker 1: Thank you.

56:34 Speaker 4: Excellent. Thank you.

56:37 Speaker 1: Question four.

56:40 Speaker 4: How can we track the stubble burning? for example, in India in real-time scenarios. Can we trace critical zones via this?

56:52 Speaker 4: This sounds like a specific example.

56:56 Speaker 2: Yeah, absolutely.

56:57 Speaker 3: And I can take a first stab at this. And I don't know if Leslie's got some thoughts to build off.

57:02 Speaker 2: Of my answer.

57:04 Speaker 3: I wasn't too familiar with the specifics of stubble burning. I did a little bit of Google searching. a little earlier today, but it seems like it's biomass burning, probably in agricultural environments typically, right? So, of course, we'll have methane and CO2 emissions to some degree, but I do want to state that these technologies are really best suited for point source observations, usually from anthropogenic sources like oil and gas emissions or from a landfill as an example. I suspect that this type of emission is going to be below the detection limit of EMIT, which is typically in the hundreds of kilograms per hour for methane.

57:50 Speaker 3: And for CO2 is typically limited to stationary source combustion from things like power plants and refineries, so very large concentrated point sources. So I think probably not something that we're going to be able to see with EMIT, but.

58:06 Speaker 2: There are some.

58:07 Speaker 3: Additional, you know, there is, there is a, if you're interested in looking at spectra from EMIT, you know, that over these areas, I'm sure given the coverage that we've got, you know, over India as an example, there's probably examples of maybe some smoke plumes that are associated with some stubble burning and stuff like that. And maybe there'll be some interesting analyses that come of that. But I think for methane and CO2, probably not be the right focus.

58:44 Speaker 1: Excellent.

58:45 Speaker 4: And I think we'll learn more about open source tools available for dealing with spectral level emit data. I think we'll hear more about that in part two. Okay, question five. How can I estimate methane emissions from mud volcanoes using emit and map in PRISMA? So it sounds like another specific source example.

59:10 Speaker 1: Yeah, and I can take this unless you'd like to, Andrew.

59:12 Speaker 3: Please, Leslie, go for it.

59:16 Speaker 1: Mud volcanoes are fun. Yeah, this is basically the same answer as Andrew gave, the great answer for the previous question, right, is that different satellites do different things well. There are some satellites that that collect maybe higher accuracy, but very coarse data. MIT really shines because it's giving you this great spatial information, and it's giving us information about a whole bunch of different parts of the electromagnetic spectrum. So MIT does methane, it does all these other amazing things really well.

59:47 Speaker 1: But that means there are these trade-offs where sometimes we can't see these very small localized sources that are fairly subtle enhancements on the background. So like Andrew's saying, the real strength of EMIT and these other sensors is their ability to detect what is a very, very big perturbation on top of a more subtle background. And so sometimes in order to understand the whole budget of some of these kinds of area sources that are a bit more subtle, scientists combine information from some of the other sensors that Andrew highlighted, like TROBOMI or like GOSAT, which might give us a bigger picture.

1:00:23 Speaker 1: It may not be able to pinpoint the exact sort of mud volcano or field residue that the questioners are asking about, but they help us understand in terms of the budget how those kinds of sources contribute and what fraction of sources are made up from some of these more natural kinds of phenomenon versus human-caused emissions. And I do also want to note that You know, NASA and other space agencies are actively working, along with private industry, are actively working to develop and improve techniques that allow us to get to more and more subtle sources.

1:00:56 Speaker 1: So you see some of those examples in the great work that the team does with the avarice instrument. Now, those are still going to struggle, I think, with some of these very subtle types of emission sources. But we are always working to improve and to refine our techniques so that we can see more and more of the big picture of emissions.

1:01:19 Speaker 4: Excellent.

1:01:20 Speaker 2: Thanks.

1:01:21 Speaker 4: So question six. Is there any other data available about plumes besides their shape, density, and persistence? Could, for example, isotope concentrations and shape be used to attribute to a sector on large scales so that not every plume requires manual attribution?

1:01:39 Speaker 1: Yeah.

1:01:44 Speaker 3: So this is a really great question. So I just want to clarify that just for EMID and NABIRS3, we don't have a sufficiently fine spectral resolution to distinguish sort of between isotopes in our trace gas retrieval. So I think that's unfortunately not an option. There are some instruments like these area flux mappers that are able to distinguish between certain isotopes given their spectral resolutions. So certainly there's a number of studies out there that you can perhaps refer to. Maybe I can even include a few in these after our conversation just to provide a little bit more context on some of those examples.

1:02:30 Speaker 3: But I guess the second point of your question is, yeah, about sort of the challenges of manual attribution. And it's a really good sort of question to bring up. So as I said, a little bit earlier, we do have a team of scientists that are currently working to do manual identification of these point sources. In parallel, we are developing approaches that would leverage machine learning to do this plume identification in a more automated way. We have a version that's currently being developed and being tested that will Help us go in that direction, but this is a hard problem and it's something that we've been focusing on for a number of years.

1:03:18 Speaker 3: So it's something that we'll be continuing to develop and roll out in the coming years. I think there are some nice examples. I think I showed the example from an agricultural emission where it was more of an area source rather than a.

1:03:35 Speaker 2: Distinct point source.

1:03:37 Speaker 3: We're not seeing a tremendous number of examples like that. But it's definitely possible when you see kind of a regional gradient that seems to be associated with maybe the collective contributions of lots of smaller point sources. In that example, we know that in that part of California, we have a lot of these things called confined feedlot operations that basically have a lot of dairy cows, waste lagoons, and these waste lagoons generate methane. We see that in our airborne surveys. It's much harder to see with EMIT.

1:04:13 Speaker 3: And in that example, we think that we're seeing sort of the contribution of multiple point sources that are in aggregate kind of show up as this more diffuse cloud in an area. So there's definitely examples like that in our datasets.

1:04:32 Speaker 1: Great.

1:04:33 Speaker 4: Thank you. Question seven. What was the timeframe for the Kansas pipeline detection between the detection and an agency like EPA being notified?

1:04:49 Speaker 2: Yep.

1:04:50 Speaker 3: So, that, excuse me, is a good question as well. So, as I said in the notes here, I don't know exactly what we were able to do for that example. I know that it was a very high priority to get that to that team given our work in the U.S. Greenhouse Gas Center and the fact that we are working directly with the EPA as part of that project with Leslie and the rest of the NASA team. Typically, we can share methane plume imagery with stakeholders within a few days of the EMIT observation. And this depends on obviously getting the data off of the ISS and then getting it processed and then getting it analyzed by our team as well.

1:05:33 Speaker 3: So you have to take all of that into consideration But typically, we are able to look at these results, the methane plume imagery, within a few days of them being measured on the EMET instrument on the International Space Station.

1:05:47 Speaker 2: Okay.

1:05:52 Speaker 4: Question eight has to do with permafrost. Is there a plan to address the missing area in northern latitudes, particularly to observe the methane emissions from thawing permafrost? And another sort of general, can you provide some general information on anticipated methane release from melting permafrost? Has it been detected yet? Will it be visible only by area flux increases, or would there be point sources?

1:06:18 Speaker 1: Yeah, I can take this unless you'd like to, Andrew.

1:06:20 Speaker 2: Please do, yeah.

1:06:24 Speaker 1: Yeah, so this is a good question, and it's getting to a couple of the limitations that we have with the emit instrument. that you're keying on is just the fact that the space station, because of its orbit, it's got what we call processing orbit, doesn't observe high latitudes. I think it goes up to about 55 degrees north and south. And so that means it misses a lot of these areas where we are, as scientists, concerned about understanding how high-latitude ecosystems and soils may be affected by warming.

1:06:54 Speaker 1: The other challenge that we have in those kinds of systems is that they're dark for large parts of the year. And instruments like EMIT are passive. They rely on a spectra of radiation in sunlight. And that means that in some of those shoulder seasons, it's particularly hard, even if you did have an instrument that has global coverage and sees over the poles, it's hard to distinguish those kinds of emissions when you have seasonal coverage and to... distinguish that from other types of phenomenon that might be related to temperature.

1:07:28 Speaker 1: So there's a couple of things that make it really, really hard for us to study permafrost with the emit instrument. I will say that in terms of other technology, as we mentioned, NASA is constantly working to develop and demonstrate new techniques. There's also a great instrument that's coming online in the next few years from a German space agency called Merlin. Merlin is actually a LIDAR. That means it carries its own light source. And so that means it can see during all year round, like during dark seasons.

1:07:58 Speaker 1: So that's going to be particularly interesting for us understanding high latitude ecosystems. One of the other things we also do in areas like this where we know our satellites are having a particular challenge with seeing is to have large scale field campaigns, airborne measurements. NASA has just, I think, wrapped up a long term experiment in Alaska, trying to monitor systems so that we can track these kinds of changes. In terms of permafrost emissions and the big picture of how those have been detected yet, I would say it's still a very active area of research.

1:08:36 Speaker 1: We certainly see some of these emissions at localized sites, but one of the challenges we see is that these kinds of permafrost emissions are very heterogeneous. They depend on surface topography. They depend on soil type, vegetation type. And so it's tough for us to measure maybe on the ground emissions at just one site and be able to extrapolate that to how permafrost is changing globally. And so that's where scientists are increasingly looking to this mix of ground truth, instruments that tell us about very localized sources, which are still going to be much weaker than point sources like you've seen demonstrated today.

1:09:14 Speaker 1: and some of these kinds of sensors like MERLIN that give us broader coverage and might be able to help us detect a sort of more subtle change in the area emissions that could be related to permafrost or other kinds of sources like changes in wetland emissions.

1:09:36 Speaker 2: Okay.

1:09:38 Speaker 4: Moving on to question nine. Are there undetected plants? Could you talk about how to find plumes that might be below the detection limit of EMIT?

1:09:50 Speaker 2: Yep, absolutely.

1:09:51 Speaker 3: So yes, there are certainly plumes that, if we're talking about EMIT, that EMIT is not going to be able to observe. The minimum detection limit for EMIT is on the order of hundreds of kilograms per hour, and that depends on the local wind conditions. So we know that there's going to be a distribution of emissions that are below that detection limit. And we've seen that with airborne surveys as an example. So if you were to fly airborne instrument like Everest three over, let's say the Permian basin in the United States, right?

1:10:29 Speaker 3: There will be some plumes that are observed that are smaller than what EMIT can see. And you'd see that absence in the EMIT results if you flew the same area at the same time. And we've actually done some of those flights in the past as part of our CalVal activities.

1:10:44 Speaker 2: And we see that.

1:10:45 Speaker 3: So we certainly know that there's a set of smaller emissions that we can observe with EMIT that can be observed with something like AVERIS-3 as an aircraft instrument. And then that being said, even below that detection limit of Averis 3, which is on the order of tens of kilograms per hour, there'll be smaller emissions, right, that are coming from, let's say, oil and.

1:11:08 Speaker 2: Gas operations as well.

1:11:10 Speaker 3: So there's definitely opportunities to use other technologies to get at these even smaller emissions, which are also important.

1:11:25 Speaker 4: Okay, question 10. would it be possible to detect an underground crude oil leak using remotely sensed methane data?

1:11:38 Speaker 2: Yep.

1:11:39 Speaker 3: So I think it's possible, but probably challenging. So if there was associated significant amounts of methane that were associated with the crude oil liquid, It's possible that we would be able to see that, but again, probably would be pretty challenging to do given the detection limits that I was discussing, I guess, in that last question. I do want to emphasize that the pipeline examples that I shared in the presentation were, from my understanding, they were natural gas pipelines, so much more potential methane larger emission rates than what you would expect from something like a crude oil leak.

1:12:26 Speaker 3: But I guess I've learned over many years to never say never. So we can't say that we'll never be able to do it, but it's probably going to be quite challenging.

1:12:40 Speaker 2: Okay.

1:12:40 Speaker 4: Question 11. Is it reliable to rely solely on satellite data in studies of methane emissions, air quality, or dust And can such data be considered valid in research without verification from on-the-ground measurements?

1:13:01 Speaker 1: This is a really good question. Andrew, do you want to take it or do you want.

1:13:05 Speaker 2: Me to?

1:13:06 Speaker 1: Please do. Okay. Yeah, it's a really good question. It's an insightful question. And I will say one of the things that people should know is that even when you're just using a satellite data product, we put a lot of care into how we evaluate and validate that data, which often is using a lot of different types of data sets from in situ measurements. We might use profiles of methane. In the case of some of these methane point sources, Andrew and team actually work really closely with people who do controlled releases of methane so that they can test things like emissions estimates.

1:13:42 Speaker 1: So even if you think you're just downloading a satellite data product, There's a ton of care and work that's gone into using different types of measurements to make sure that we have confidence in those data sets and that we can quantify things like uncertainty so that you know how much confidence we have in them. And so I will say that I think there's a– and I think different people have different opinions on this. I think that there are, in a lot of cases, the ability to use very high-quality, well-validated data data sets from remote sensing independent of other types of observations, but there are different viewpoints on that.

1:14:22 Speaker 1: For example, in some EPA regulations, including some that have been enacted over the past year or so, they're opening the door to use of more and more remote sensing information, but often when it's combined with other types of measurements. For scientific analyses, I think there are a lot of cases where we're comfortable using those kinds of data sets, but also have different methods for showing the quality, showing the traceability to other types of measurements that are well validated. So there's a little bit of a judgment call here about whether or not it's appropriate for a particular use case to use the satellite data independently.

1:15:01 Speaker 1: But I think in a lot of cases, like detecting a very large enhancement about the background, like Andrew's talked a great deal about, We know and have a great deal of confidence in the way that those instruments perform, and we know that those detections are very, very reliable, especially because we go through a lot of care of quality control and screening before the data is released to the public. So that would be my take. I don't know, Andrew, if you have any other thoughts on this, but this is an interesting one and certainly one that's a little bit of a judgment call.

1:15:31 Speaker 3: Yeah, no, I agree with everything that you said. I think, you know, I would just emphasize that, you know, we– as Leslie said, right, the technologies are rooted on key studies that have leveraged in-situ measurements for validation, and that's the controlled releases, but also things like, on the point source side, like literally when I was in graduate school, right, I was driving around with a thermal camera in an oil and gas field verifying plumes that were observed with the avarice next-gen instrument, right, and things like that, and we've done that with satellite observations as well, and I think that provides a nice foundation for showing that you have to make the case that what you're seeing from space or from an aircraft melds with reality with what's seen on the ground.

1:16:20 Speaker 3: But that being said, right, there are people that are publishing very good studies that are really just focusing on, let's say, identifying methane point sources, let's say, in the Permian Basin, right, and doing really interesting and sort of transformative formational science, right, that aren't necessarily, they don't necessarily have a ground crew in the field, right, doing.

1:16:47 Speaker 2: Inner comparisons, right, in the way that I did in graduate school.

1:16:50 Speaker 3: I think that's okay, but what they are doing is that they're citing previous papers, right, and they're talking about controlled release experiments that have been published in the past to provide the level of, I guess, scientific context that's required, right, to publish these kinds of studies.

1:17:11 Speaker 2: Thanks.

1:17:13 Speaker 4: Okay, question 12. Is the EMIT or other satellite sensor able to retrieve methane and CO2 emissions from wildfires? Have any results been demonstrated for this emission sector?

1:17:30 Speaker 3: And you can see it as a work in progress, trying to type out an answer here. But for EMIT,

1:17:41 Speaker 3: We've always been very, very interested in wildfires for both CO2 and methane emissions.

1:17:53 Speaker 2: I think sort of going back to some of the previous.

1:17:57 Speaker 3: Answers, it's very hard to do this for wildfires because the emissions are less point source-like and they're more diffuse sort of area-wide emissions. It's something that we're looking at a few examples, but it's really pushing our capability. So I would hesitate to say that we think we can do this from an instrument like EMIT. There are certainly other instruments out there that have published papers showing CO2 emissions from wildfires, but it's just not something that we've demonstrated with EMIT.

1:18:43 Speaker 4: Okay, question 13. It was a bit strange to see that methane contribution to heat imbalance has been relatively constant.

1:18:51 Speaker 1: It's. 4 watts per meter.

1:18:54 Speaker 4: Can you comment? This sounds like a question about the introduction.

1:18:58 Speaker 1: Yeah, and I can chime in just really briefly. I think this has to do a lot with the context of that plot. So that's an estimate from NOAA on the combined heating influence of different gases. And what they're looking at is the relative warming sense the pre-industrial period. And so what happens is even though you see a lot of those kind of wiggles on the methane graph where we're kind of zooming in to show you the concentration changes, when we add that up and we put that in the global context of radiative forcing along with other gases, that's where that appears very subtle.

1:19:34 Speaker 1: And it's a good lesson in the way that we present different graphs and whether they're zooming in to highlight recent changes or to show the big picture of warming that's happened. So really that's just what you're seeing is the, I think, difference in how those different graphs and the y-oxys are showing up. Gotcha.

1:19:57 Speaker 4: Okay, question 14. When a dam is storing water, does the submerged vegetation potentially generate significant methane?

1:20:12 Speaker 2: Well, I think... Yeah, go for it, Andrew. First stab at this one.

1:20:16 Speaker 3: So I think it's definitely possible that submerged vegetation can actually, in some cases, provide like a pathway for methane.

1:20:32 Speaker 2: So I'm talking more in.

1:20:33 Speaker 3: The context of some previous studies that I was a part of in the Arctic with the Avarice Next Generation Instrument that was actually able to find these localized hot spots of methane that were associated with permafrost slumping. And we had a colleague go into the field and verify with some in-situ measurements what we were seeing in the aircraft. And in that example, I know that there's a certain type of vegetation, and I don't know the name off the top of my head, that kind of acts as like a soda straw where the methane from the subsurface can get into the atmosphere.

1:21:08 Speaker 3: I'm not sure about in a dam if similar types of vegetation exist. That being said, I think dams are known to be significant methane emitters, right? And it's something that is of great interest to the broader community is looking at dams and figuring out can we see methane emissions that we suspect are at these locations. And to date, we've been looking at a few dams with emit We've seen some interesting results, but nothing definitive. So we haven't published any of those results. I think this is something that with future instruments that are coming online, we'll likely do a little bit better job of this going forward.

1:21:56 Speaker 3: I don't know, Leslie, if you've got any additional thoughts there.

1:22:01 Speaker 1: No, I think you handled it perfectly. It's a challenging environment. It's also challenging to make those kinds of observations in a scene that has water in it, just for a variety of reasons related to maroon and something. So I think Andrew's totally right. This is one of those things where it's work in progress, but also recognizing this is something we're hearing increasingly from stakeholders, that it's a challenge for them to be able to quantify emissions from those kinds of man-made sources.

1:22:24 Speaker 1: And so it is certainly something NASA's working on, even though I think it's a really tough measurement to make and interpret. especially the vegetation under the water.

1:22:36 Speaker 4: Okay, maybe we have time for maybe one or two quick questions. Can you scroll down to question 18? I thought this might be, so in a lot of the images shown during today's training, they had units of PPM per meter. Can you comment about what that means for image interpretation?

1:22:59 Speaker 2: Yes, absolutely.

1:23:00 Speaker 3: So this is a really great question. So it is, the units are actually PPM dot M, so not divided by M. And the idea here is that this technology is really measuring an enhancement above background. And what we don't know is where in the atmosphere that enhancement is located in our atmospheric column. just because of the spectral sampling interval to 7.4 nanometers with EMET doesn't allow us to say anything about where that methane is. It's sort of a total column value. So what we've done over a number of years is to use this nomenclature to indicate what is the enhancement in terms of parts per million in a one meter layer.

1:23:51 Speaker 3: And if you can adjust that by scaling what your assumption is.

1:23:57 Speaker 2: If you assume.

1:23:59 Speaker 3: That that gas is concentrated near the ground in a one meter layer, that's what that PPM-dot-M value would be. If you wanted to rescale that to a plume that was 500 meters off, you could scale that and that number would decrease proportionately. But that's the distinction there. You can also convert that unit, and I can refer, maybe I can follow up with a specific reference, but you can also convert that unit into a mass unit, something like moles per square meter. And we basically, that's a prerequisite for how we do our emission rate estimation, right?

1:24:47 Speaker 3: We have to go from a PPMN.M unit to a mass unit, unit and then use that by combining that with a wind speed, a plume light to estimate the emission rate.

1:25:01 Speaker 2: Excellent.

1:25:02 Speaker 4: Well, that takes us to the end of our time today. Thank you so much to our guests for your thoughtful presentation and your thorough answers to these questions. For the questions that we didn't get to, we'll address them offline and we'll post this entire transcript to the training page within about a week of the training. Thank you so much for joining us today, and we hope that you will join us on Thursday for part two. Thank you so much, everyone.