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By NASA
10 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Return to 2024 SARP Closeout Faculty Advisors:
Dr. Guanyu Huang, Stony Brook University
Graduate Mentor:
Ryan Schmedding, McGill University
Ryan Schmedding, Graduate Mentor
Ryan Schmedding, graduate mentor for the 2024 SARP Atmospheric Science group, provides an introduction for each of the group members and shares behind-the scenes moments from the internship.
Danielle Jones
Remote sensing of poor air quality in mountains: A case study in Kathmandu, Nepal
Danielle Jones
Urban activity produces particulate matter in the atmosphere known as aerosol particles. These aerosols can negatively affect human health and cause changes to the climate system. Measures for aerosols include surface level PM2.5 concentration and aerosol optical depth (AOD). Kathmandu, Nepal is an urban area that rests in a valley on the edge of the Himalayas and is home to over three million people. Despite the prevailing easterly winds, local aerosols are mostly concentrated in the valley from the residential burning of coal followed by industry. Exposure to PM2.5 has caused an estimated ≥8.6% of deaths annually in Nepal. We paired NASA satellite AOD and elevation data, model meteorological data, and local AirNow PM2.5 and air quality index (AQI) data to determine causes of variation in pollutant measurement during 2023, with increased emphasis on the post-monsoon season (Oct. 1 – Dec. 31). We see the seasonality of meteorological data related to PM2.5 and AQI. During periods of low temperature, low wind speed, and high pressure, PM2.5 and AQI data slightly diverge. This may indicate that temperature inversions increase surface level concentrations of aerosols but have little effect on the total air column. The individual measurements of surface pressure, surface temperature, and wind speed had no observable correlation to AOD (which was less variable than PM2.5 and AQI over the entire year). Elevation was found to have no observable effect on AOD during the period of study. Future research should focus on the relative contributions of different pollutants to the AQI to test if little atmospheric mixing causes the formation of low-altitude secondary pollutants in addition to PM2.5 leading to the observed divergence in AQI and PM2.5.
Madison Holland
Analyzing the Transport and Impact of June 2023 Canadian Wildfire Smoke on Surface PM2.5 Levels in Allentown, Pennsylvania
Madison Holland
The 2023 wildfire season in Canada was unparalleled in its severity. Over 17 million hectares burned, the largest area ever burned in a single season. The smoke from these wildfires spread thousands of kilometers, causing a large population to be exposed to air pollution. Wildfires can release a variety of air pollutants, including fine particulate matter (PM2.5). PM2.5 directly affects human health – exposure to wildfire-related PM2.5 has been associated with respiratory issues such as the exacerbation of asthma and chronic obstructive pulmonary disease. In June 2023, smoke from the Canadian wildfires drifted southward into the United States. The northeastern United States reported unhealthy levels of air quality due to the transportation of the smoke. In particular, Pennsylvania reported that Canadian wildfires caused portions of the state to have “Hazardous” air quality. Our research focused on how Allentown, PA experienced hazardous levels of air quality from this event. To analyze the concentrations of PM2.5 at the surface level, NASA’s Hazardous Air Quality Ensemble System (HAQES) and the EPA’s Air Quality System (AQS) ground-based site data were utilized. By comparing HAQES’s forecast of hazardous air quality events with recorded daily average PM2.5 with the EPA’s AQS, we were able to compare how well the ensemble system was at predicting total PM2.5 during unhealthy air quality days. NOAA’s Hybrid Single-Particle Lagrangian Integrated Trajectory model, pyrsig, and the Canadian National Fire Database were used. These datasets revealed the trajectory of aerosols from the wildfires to Allentown, Pennsylvania, identified the densest regions of the smoke plumes, and provided a map of wildfire locations in southeastern Canada. By integrating these datasets, we traced how wildfire smoke transported aerosols from the source at the ground level.
Michele Iraci
Trends and Transport of Tropospheric Ozone From New York City to Connecticut in the Summer of 2023
Michele Iraci
Tropospheric Ozone, or O₃, is a criteria pollutant contributing to most of Connecticut and New York City’s poor air quality days. It has adverse effects on human health, particularly for high-risk individuals. Ozone is produced by nitrogen oxides and volatile organic compounds from fuel combustion reacting with sunlight. The Ozone Transport Region (OTR) is a collection of states in the Northeast and Mid-Atlantic United States that experience cross-state pollution of O₃. Connecticut has multiple days a year where O₃ values exceed the National Ambient Air Quality Standards requiring the implementation of additional monitoring and standards because it falls in the OTR. Partially due to upstream transport from New York City, Connecticut experiences increases in O₃ concentrations in the summer months. Connecticut has seen declines in poor air quality days from O₃ every year due to the regulations on ozone and its precursors. We use ground-based Lidar, Air Quality System data, and a back-trajectory model to examine a case of ozone enhancement in Connecticut caused by air pollutants from New York between June and August 2023. In this time period, Connecticut’s ozone enhancement was caused by air pollutants from New York City. As a result, New York City and Connecticut saw similar O₃ spikes and decline trends. High-temperature days increase O₃ in both places, and wind out of the southwest may transport O₃ to Connecticut. Production and transport of O₃ from New York City help contribute to Connecticut’s poor air quality days, resulting in the need for interstate agreements on pollution management.
Stefan Sundin
Correlations Between the Planetary Boundary Layer Height and the Lifting Condensation Level
Stefan Sundin
The Planetary Boundary Layer (PBL) characterizes the lowest layer in the atmosphere that is coupled with diurnal heating at the surface. The PBL grows during the day as solar heating causes pockets of air near the surface to rise and mix with cooler air above. Depending on the type of terrain and surface albedo that receives solar heating, the depth of the PBL can vary to a great extent. This makes PBL height (PBLH) a difficult variable to quantify spatially and temporally. While several methods have been used to obtain the PBLH such as wind profilers and lidar techniques, there is still a level of uncertainty associated with PBLH. One method of predicting seasonal PBLH fluctuation and potentially lessening uncertainty that will be discussed in this study is recognizing a correlation in PBLH with the lifting condensation level (LCL). Like the PBL, the LCL is used as a convective parameter when analyzing upper air data, and classifies the height in the atmosphere at which a parcel becomes saturated when lifted by a forcing mechanism, such as a frontal boundary, localized convergence, or orographic lifting. A reason to believe that PBLH and LCL are interconnected is their dependency on both the amount of surface heating and moisture that is present in the environment. These thermodynamic properties are of interest in heavily populated metropolitan areas within the Great Plains, as they are more susceptible to severe weather outbreaks and associated economic losses. Correlations between PBLH and LCL over the Minneapolis-St. Paul metropolitan statistical area during the summer months of 2019-2023 will be discussed.
Angelica Kusen
Coupling of Chlorophyll-a Concentrations and Aerosol Optical Depth in the Subantarctic Southern Ocean and South China Sea (2019-2021)
Angelica Kusen
Air-sea interactions form a complex feedback mechanism, whereby aerosols impact physical and biogeochemical processes in marine environments, which, in turn, alter aerosol properties. One key indicator of these interactions is chlorophyll-a (Chl-a), a pigment common to all phytoplankton and a widely used proxy for primary productivity in marine ecosystems. Phytoplankton require soluble nutrients and trace metals for growth, which typically come from oceanic processes such as upwelling. These nutrients can also be supplied via wet and dry deposition, where atmospheric aerosols are removed from the atmosphere and deposited into the ocean. To explore this interaction, we analyze the spatial and temporal variations of satellite-derived chl-a and AOD, their correlations, and their relationship with wind patterns in the Subantarctic Southern Ocean and the South China Sea from 2019 to 2021, two regions with contrasting environmental conditions.
In the Subantarctic Southern Ocean, a positive correlation (r²= 0.26) between AOD and Chl-a was found, likely due to dust storms following Austrian wildfires. Winds deposit dust aerosols rich in nutrients, such as iron, to the iron-limited ocean, enhancing phytoplankton photosynthesis and increasing chl-a. In contrast, the South China Sea showed no notable correlation (r² = -0.02) between AOD and chl-a. Decreased emissions due to COVID-19 and stricter pollution controls likely reduced the total AOD load and shifted the composition of aerosols from anthropogenic to more natural sources.
These findings highlight the complex interrelationship between oceanic biological activity and the chemical composition of the atmosphere, emphasizing that atmospheric delivery of essential nutrients, such as iron and phosphorus, promotes phytoplankton growth. Finally, NASA’s recently launched PACE mission will contribute observations of phytoplankton community composition at unprecedented scale, possibly enabling attribution of AOD levels to particular groups of phytoplankton.
Chris Hautman
Estimating CO₂ Emission from Rocket Plumes Using in Situ Data from Low Earth Atmosphere
Chris Hautman
Rocket emissions in the lower atmosphere are becoming an increasing environmental concern as space exploration and commercial satellite launches have increased exponentially in recent years. Rocket plumes are one of the few known sources of anthropogenic emissions directly into the upper atmosphere. Emissions in the lower atmosphere may also be of interest due to their impacts on human health and the environment, in particular, ground level pollutants transported over wildlife protected zones, such as the Everglades, or population centers near launch sites. While rockets are a known source of atmospheric pollution, the study of rocket exhaust is an ongoing task. Rocket exhaust can have a variety of compositions depending on the type of engine, the propellants used, including fuels, oxidizers, and monopropellants, the stoichiometry of the combustion itself also plays a role. In addition, there has been increasing research into compounds being vaporized in atmospheric reentry. These emissions, while relatively minimal compared to other methods of travel, pose an increasing threat to atmospheric stability and environmental health with the increase in human space activity. This study attempts to create a method for estimating the total amount of carbon dioxide released by the first stage of a rocket launch relative to the mass flow of RP-1, a highly refined kerosene (C₁₂H₂₆)), and liquid oxygen (LOX) propellants. Particularly, this study will focus on relating in situ CO₂ emission data from a Delta II rocket launch from Vandenberg Air Force Base on April 15, 1999, to CO₂ emissions from popular modern rockets, such as the Falcon 9 (SpaceX) and Soyuz variants (Russia). The findings indicate that the CO₂ density of any RP-1/LOX rocket is 6.9E-7 times the mass flow of the sum of all engines on the first stage. The total mass of CO₂ emitted can be further estimated by modeling the volume of the plume as cylindrical. Therefore, the total mass can be calculated as a function of mass flow and first stage main engine cutoff. Future CO₂ emissions on an annual basis are calculated based on these estimations and anticipated increases in launch frequency.
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Last Updated Nov 22, 2024 Related Terms
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By NASA
Associate Director for Mission Planning, Earth Sciences, and environmental scientist Robert J. “Bob” Swap makes a difference by putting knowledge into action.
Name: Robert J. “Bob” Swap
Title: Associate Director for Mission Planning, Earth Sciences
Organization: Earth Science Division (Code 610)
Robert Swap (right) and Karen St. Germain, NASA Earth science director (left) joined NASA’s Student Airborne Research Program, an eight-week summer internship program for rising senior undergraduates during summer 2023. Photo courtesy of Robert Swap What do you do and what is most interesting about your role here at Goddard?
I work with our personnel to come up with the most viable mission concepts and put together the best teams to work on these concepts. I love working across the division, and with the center and the broader community, to engage with diverse competent teams and realize their potential in address pressing challenges in the earth sciences.
Why did you become an Earth scientist?
In the mid to late ’70s, the environment became a growing concern. I read all the Golden Guides in the elementary school library to learn about different creatures. I grew up exploring and discovering the surrounding woods, fields, and creeks, both on my own and through scouting and became drawn to nature, its connectedness, and its complexity. The time I spent fishing with my father, a military officer who also worked with meteorology, and my brother helped cement that love. I guess you could say that I became “hooked.”
What is your educational background?
In 1987, I got a B.A. in environmental science from the University of Virginia. While at UVA, I was a walk-on football player, an offensive lineman on UVA’s first ever post-season bowl team. This furthered my understanding of teamwork, how to work with people who were much more skilled than I was, and how to coach. I received master’s and Ph.D. degrees in environmental science from UVA in 1990 and 1996, respectively.
As an undergraduate in environmental sciences, I learned about global biochemical cycling — meaning how carbon and nitrogen move through the living and nonliving systems — while working on research teams in the Chesapeake Bay, the Blue Ridge Mountains and the Amazon Basin.
Before graduating I had the good fortune to participate in the NASA Amazon Boundary Layer Experiment (ABLE-2B) in the central Amazon, which I used to kick off my graduate studies. I then focused on southern African aerosol emissions, transports and depositions for my doctoral studies that ultimately led to a university research fellow postdoc at the University of the Witwatersrand in Johannesburg, South Africa.
What are some of your career highlights?
It has been a crazy journey!
While helping put up meteorological towers in the Amazon deep jungle, we would encounter massive squall lines. These storms were so loud as they rained down on the deep forest that you could not hear someone 10 feet away. One of the neatest things that I observed was that after the storms passed, we would see a fine red dust settling on top of our fleet of white Volkswagen rental vehicles in the middle of the rainforest.
That observation piqued my interest and led to a paper I wrote about Saharan dust being transported to the Amazon basin and its potential implications for the Amazon, especially regarding nutrient losses from the system. Our initial work suggested there was not enough input from Northern Africa to support the system’s nutrient losses. That caused us to start looking to Sub-Saharan Africa as a potential source of these nutritive species.
I finished my master’s during the first Persian Gulf War, and finding a job was challenging. During that phase I diversified my income stream by delivering newspapers and pizzas and also bouncing at a local nightspot so that I could focus on writing papers and proposals related to my research. One of my successes was the winning of a joint National Science Foundation proposal that funded my doctoral research to go to Namibia and examine sources of aerosol and trace gases as part of the larger NASA TRACE-Southern African Atmosphere Fire Research Initiative – 92 (SAFARI-92). We were based at Okaukuejo Rest Camp inside of Namibia’s Etosha National Park for the better part of two months. We characterized conservative chemical tracers of aerosols, their sources and long-range transport from biomass burning regions, which proved, in part, that Central Southern Africa was providing mineral and biomass burning emissions containing biogeochemically important species to far removed, downwind ecosystems thousands of kilometers away.
When I returned to Africa as a postdoctoral fellow, I was able to experience other countries and cultures including Lesotho, Mozambique, and Zambia. In 1997, NASA’s AERONET project was also expanding into Africa and I helped Brent Holben and his team deploy instruments throughout Africa in preparation for vicarious validation of instrumentation aboard NASA’s Terra satellite platform.
I returned to UVA as a research scientist to work for Chris Justice and his EOS MODIS/Terra validation team. I used this field experience and the international networks I developed, which contributed to my assuming the role of U.S. principal investigator for NASA’s Southern African Regional Science Initiative. Known as SAFARI 2000, it was an effort that involved 250 scientists from 16 different countries and lasted more than three years. When it ended, I became a research professor and began teaching environmental science and mentoring UVA students on international engagement projects.
Around 2000, I created a regional knowledge network called Eastern/Southern Africa Virginia Network and Association (ESAVANA) that leveraged the formal and informal structures and networks that SAFARI 2000 established. I used my team building and science diplomacy skills to pull together different regional university partners, who each had unique pieces for unlocking the larger puzzle of how southern Africa acted as a regional coupled human-natural system. Each partner had something important to contribute while the larger potential was only possible by leveraging their respective strengths together as a team.
I traveled extensively during this time and was supported in 2001 partially by a Fulbright Senior Specialist Award which allowed me to spend time at the University of Eduardo Mondlane in Maputo Mozambique to help them with hydrology ecosystem issues in the wake of massive floods. We kept the network alive by creating summer study abroad, service learning and intersession January educational programs that drew upon colleagues and their expertise from around the world that attracted new people, energy, and resources to ESAVANA. All of these efforts contributed to a “community of practice” focused on learning about the ethics and protocols of international research. The respectful exchange of committed people and their energies and ideas was key to the effort’s success. I further amplified the impact of this work by contributing my lived and learned experiences to the development of the first ever global development studies major at UVA.
In 2004, I had a bad car accident and as a result have battled back and hip issues ever since. After falling off the research funding treadmill, I had to reconfigure myself in the teaching and program consultant sector. I grew more into a teaching role and was recognized for it by UVA’s Z-Society 2008 Professor of the Year, the Carnegie Foundation for the Advancement of Teaching’s Virginia’s 2012 Professor of the Year, as well as my 2014 induction into UVA’s Academy of Teaching — all while technically a research professor. I was also heavily involved for almost a decade with the American Association for the Advancement of Science and its Center for Science Diplomacy and tasks related to activities such as reviewing the Inter-American Institute for Global Change Research and teaching science diplomacy in short courses for the World Academy of Sciences for the Advancement of Science in Developing Countries located in Trieste, Italy, and the Academy of Science of South Africa.
I worked in the Earth Sciences Division at NASA Headquarters from 2014 to early 2017 as a rotating program support officer as part of the Intergovernmental Personnel Act (IPA), where I supported the atmospheric composition focus area. One of my responsibilities involved serving as a United States Embassy science fellow in the summer of 2015, where I went to Namibia to support one of our Earth Venture Suborbital field campaigns. I came to Goddard in April 2017 to help revector their nascent global network of ground-based, hyperspectral ultraviolet and visible instruments known as the Pandora.
What is your next big project?
I am currently working with the NASA Goddard Earth Science Division front office to craft a vision for the next 20 years, which involves the alignment of people around a process to achieve a desired product. With the field of Earth System Science changing so rapidly, we need to position ourselves within this ever evolving “new space” environment of multi-sectoral partners — governmental, commercial, not-for-profit, and academic — from the U.S. and beyond to study the Earth system. This involves working with other governmental agencies, universities and industrial partners to chart a way forward. We will have a lot of new players. We will be working with partners we never imagined.
We need people who know how to work across these different sectors. One such attempt to “grow our own timber” involves my development of an experimental version of the first NASA Student Airborne Research Program East Coast Edition (SARP and SARP-East), where student participants from a diversity of institutions of higher learning can see the power and promise of what NASA does, how we work together on big projects, and hopefully be inspired to take on the challenges of the future. In other words, I am pushing an exposure to field-based, Earth system science down earlier into their careers to expose them to what NASA does in an integrated fashion.
What assets do you bring to the Earth Science Division front office?
In 2020, I came to the Earth science front office to help lead the division. I make myself available across the division to help inspire, collect, suggest, and coach our rank and file into producing really cool mission concept ideas.
Part of why the front office wanted me is because I use the skills of relationship building, community building, and science diplomacy to make things happen, to create joint ventures. Having had to support myself for over 20 years on soft money, I learned to become an entrepreneur of sorts — to be scientifically and socially creative — and I was forced to look inward and take an asset-based approach. I look at all the forms of capital I have at hand and use those to make the best of what I have got. In Appalachia, there is an expression: use everything but the squeal from the pig.
Lastly, I bring a quick wit with a good dose of self-deprecating humor that helps me connect with people.
How do you use science diplomacy to make things happen?
Two of the things that bind people together about science are the process of inquiry and utilizing the scientific method, both of which are universally accepted. As such, they allow us to transcend national and cultural divides.
Science diplomacy works best when you start with this common foundation. Starting with this premise in collaborative science allows for conversations to take place focusing on what everyone has in common. You can have difficult conversations and respectful confrontations about larger issues.
Scientists can then talk and build bridges in unique ways. We did this with SAFARI 2000 while working in a region that had seen two major wars and the system of Apartheid within the previous decade. We worked across borders of people who were previously at odds. We did that by looking at something apart from national identity, which was Southern Africa. We focused on how a large-scale system functions and how to make something that incorporates 10 different countries operate as a unit. We wanted to conduct studies showing how the region operated as a functional unit while dealing with transboundary issues. It took a lot of community and trust, and we began with the science community.
What drives you?
I want to put knowledge into action to make a difference. I realize it is not about me, it is about “we.” That is why I came to NASA, to make a difference. There is no other agency in the world where we can harness such a unique and capable group of people.
What do you do for fun?
I enjoy watching sports. I still enjoy hiking, fishing, and tubing down the river. My wife and I like long walks through natural settings with our rescues, Lady, our black-and-tan coonhound, and Duchess, our long-haired German Shepherd Dog. They are our living hot water bottles in the winter.
My wife and I also like to cook together.
Who would you like to thank?
Without a doubt, it starts with my wife, family, and children whom without none of what I have accomplished would have been possible. I have had the good fortune to be able to bring them along on some of my international work, including to Africa.
I am also very grateful to all those people during my school years who stepped in and who did not judge me initially by my less than stellar grades. They gave me the chance to become who I am today.
Who inspires you?
There is an old television show that I really liked called “Connections,” by James Burke. He would start with a topic, go through the history, and show how one action led to another action with unforeseen consequences. He would take something modern like plastics and link it back to Viking times. Extending that affinity for connections, the Resilience Alliance out of Sweden also influences me with their commitment to showing connections and cycles.
My mentors at UVA were always open to serving as a sounding board. They treated me as a colleague, not a student, as a member of the guild even though I was still an apprentice. That left an indelible impression upon me and I always try to do the same. My doctoral mentor Mike Garstang said that he already had a job and that this job was to let me stand on his shoulders to allow me to get to the next level, which is my model.
Another person who was very formative during my early professional career was Jerry Melillo who showed me what it was like to be an effective programmatic mentor. I worked with him as his chief staffer of an external review of the IAI and learned a lot by watching how he ran that activity program.
With respect to NASA, a number of people come to mind: Michael King, Chris Justice, and Tim Suttles, as well as my South African Co-PI, Harold Annegarn, all of whom, at one time or another, took me under their respective wings and mentored me through the whole SAFARI 2000 process. From each of their different perspectives, they taught me how NASA works, how to engage, how to implement a program, and how to navigate office politics. And my sister and our conversations about leadership and what it means to be a servant leader. To be honest, there are scores more individuals who have contributed to my development that I don’t have the space to mention here.
What are some of your guiding principles?
Never lose the wonder — stay curious. “We” not “me.” Seeking to understand before being understood. We all stand on somebody’s shoulders. Humility rather than hubris. Respect. Be the change you wish to see.
By Elizabeth M. Jarrell
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Conversations With Goddard is a collection of Q&A profiles highlighting the breadth and depth of NASA’s Goddard Space Flight Center’s talented and diverse workforce. The Conversations have been published twice a month on average since May 2011. Read past editions on Goddard’s “Our People” webpage.
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Last Updated Nov 19, 2024 EditorMadison OlsonContactRob Garnerrob.garner@nasa.govLocationGoddard Space Flight Center Related Terms
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By NASA
Anthocyanins protect seeds in space
After exposure to space outside the International Space Station, purple-pigmented rice seeds rich in anthocyanin had higher germination rates than non-pigmented white rice seeds. This result suggests that anthocyanin, a flavonoid known to protect plants from UV irradiation, could help preserve seed viability on future space missions.
Plants are key components for systems being designed to produce nutrients and recycle carbon for future sustained space habitation, but space has been shown to reduce seed viability. Tanpopo-3, part of a series of investigations from JAXA (Japan Aerospace Exploration Agency), examined the role of anthocyanins in maintaining seed viability. Results of this and previous experiments suggest that solar light in space is more detrimental to seeds than radiation.
Preflight image of the Tanpopo panel used to expose seeds and other samples to space. Tanpopo-3 team Low-cost, autonomous technology validated for space research
Researchers verified a pair of devices for conducting experiments in space that have multi-step reactions and require automatic mixing of solutions. This type of low-cost, autonomous technology expands the possibilities for space-based research, including work by commercial entities.
Ice Cubes #6- Kirara, an investigation from ESA (European Space Agency) developed by the Japan Manned Space Systems Corporation, used a temperature-controlled incubator to crystallize proteins in microgravity. The Kirara facility also enables production of polymers, including cellulose, which have different uses than protein crystals. This experiment synthesized and decomposed cellulose.
The Kirara incubator used for experiments in microgravity. United Arab Emirates/Sultan Alneyadi Insights from observations of an X-ray binary star
Researchers used Neutron star Interior Composition Explorer (NICER) to observe the timing of 15 X-ray bursts from 4U 1820–30, an ultracompact X-ray binary (UCXB) star. An X-ray binary is a neutron star orbiting a companion from which it takes matter. If confirmed with future observations, this result makes 4U 1820–30 the fastest-spinning neutron star known in an X-ray binary system and provides insights into the physics of neutron stars.
NICER makes high-precision measurements of neutron stars (the ultra-dense matter created when massive stars explode as supernovas) and other phenomena to increase our understanding of the universe. NICER has monitored 4U 1820–30 since its launch in June 2017. A short orbital period indicates a relatively small binary system, and 4U 1820–30 has the shortest known orbital period among low-mass X-ray binaries.
Animated image of a binary star system,NASA’s Goddard Space Flight Center/Chris SmithView the full article
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA’s EMIT collected this hyperspectral image of the Amazon River in northern Brazil on June 30 as part of an effort to map global ecosystem biodiversity. The instrument was originally tasked with mapping minerals over deserts; its data is now being used in research on a diverse range of topics. NASA/JPL-Caltech The imaging spectrometer measures the colors of light reflected from Earth’s surface to study fields such as agriculture, hydrology, and climate science.
Observing our planet from the International Space Station since July 2022, NASA’s EMIT (Earth Surface Mineral Dust Source Investigation) mission is beginning its next act.
At first the imaging spectrometer was solely aimed at mapping minerals over Earth’s desert regions to help determine the cooling and heating effects that dust can have on regional and global climate. The instrument soon added another skill: pinpointing greenhouse gas emission sources, including landfills and fossil fuel infrastructure.
Following a mission extension this year, EMIT is now collecting data from regions beyond deserts, addressing topics as varied as agriculture, hydrology, and climate science.
Imaging spectrometers like EMIT detect the light reflected from Earth, and they separate visible and infrared light into hundreds of wavelength bands — colors, essentially. Scientists use patterns of reflection and absorption at different wavelengths to determine the composition of what the instrument is observing. The approach echoes Isaac Newton’s prism experiments in 1672, in which the physicist discovered that visible light is composed of a rainbow of colors.
Perched on the International Space Station, NASA’s EMIT can differentiate between types of vegetation to help researchers understand the distribution and traits of plant communities. The instrument collected this data over the mid-Atlantic U.S. on April 23.NASA/JPL-Caltech “Breakthroughs in optics, physics, and chemistry led to where we are today with this incredible instrument, providing data to help address pressing questions on our planet,” said Dana Chadwick, EMIT’s applications lead at NASA’s Jet Propulsion Laboratory in Southern California.
New Science Projects
In its extended mission, EMIT’s data will be the focus of 16 new projects under NASA’s Research Opportunities in Space and Earth Science (ROSES) program, which funds science investigations at universities, research institutions, and NASA.
For example, the U.S. Geological Survey (USGS) and the U.S. Department of Agriculture’s (USDA) Agricultural Research Service are exploring how EMIT can assess climate-smart agricultural practices. Those practices — winter cover crops and conservation tillage — involve protecting cropland during non-growing seasons with either living plants or dead plant matter to prevent erosion and manage nitrogen.
Imaging spectrometers are capable of gathering data on the distribution and characteristics of plants and plant matter, based on the patterns of light they reflect. The information can help agricultural agencies incentivize farmers to use sustainable practices and potentially help farmers manage their fields.
“We’re adding more accuracy and reducing error on the measurements we are supplying to end users,” said Jyoti Jennewein, an Agricultural Research Service research physical scientist based in Fort Collins, Colorado, and a project co-lead.
The USGS-USDA project is also informing analytical approaches for NASA’s future Surface Biology and Geology-Visible Shortwave Infrared mission. The satellite will cover Earth’s land and coasts more frequently than EMIT, with finer spatial resolution.
Looking at Snowmelt
Another new project will test whether EMIT data can help refine estimates of snowpack melting rates. Such an improvement could inform water management in states like California, where meltwater makes up the majority of the agricultural water supply.
Imaging spectrometers like EMIT measure the albedo of snow — the percentage of solar radiation it’s reflecting. What isn’t reflected is absorbed, so the observations indicate how much energy snow is taking in, which in turn helps with estimates of snow melt rates. The instruments also discern what’s affecting albedo: snow-grain size, dust or soot contamination, or both.
For this work, EMIT’s ability to measure beyond visible light is key. Ice is “pretty absorptive at near-infrared and the shortwave infrared wavelengths,” said Jeff Dozier, a University of California, Santa Barbara professor emeritus and the project’s principal investigator.
Other ROSES-funded projects focus on wildflower blooming, phytoplankton and carbon dynamics in inland waters, ecosystem biodiversity, and functional traits of forests.
Dust Impacts
Researchers with EMIT will continue to study the climate effects of dust. When lofted into the air by windstorms, darker, iron-filled dust absorbs the Sun’s heat and warms the surrounding air, while lighter-colored, clay-rich particles do the opposite. Scientists have been uncertain whether airborne dust has overall cooling or warming effects on the planet. Before EMIT, they could only assume the color of particles in a region.
The EMIT mission is “giving us lab-quality results, everywhere we need to know,” said Natalie Mahowald, the mission’s deputy principal investigator and an Earth system scientist at Cornell University in Ithaca, New York. Feeding the data into Earth system computer models, Mahowald expects to get closer to pinpointing dust’s climate impact as Earth warms.
Greenhouse Gas Detection
The mission will continue to identify point-source emissions of methane and carbon dioxide, the greenhouse gases most responsible for climate change, and observations are available through EMIT’s data portal and the U.S. Greenhouse Gas Center.
The EMIT team is also refining the software that identifies and measures greenhouse-gas plumes in the data, and they’re working to streamline the process with machine-learning automation. Aligning with NASA’s open science initiative, they are sharing code with public, private, and nonprofit organizations doing similar work.
“Making this work publicly accessible has fundamentally pushed the science of measuring point-source emissions forward and expanded the use of EMIT data,” said Andrew Thorpe, the JPL research technologist heading the EMIT greenhouse gas effort.
More About EMIT
The EMIT instrument was developed by NASA’s Jet Propulsion Laboratory, which is managed for the agency by Caltech in Pasadena, California. Launched to the International Space Station in July 2022, EMIT is on an extended three-year mission in which it’s supporting a range of research projects. EMIT’s data products are available at the NASA Land Processes Distributed Active Archive Center for use by other researchers and the public.
To learn more about the mission, visit:
https://earth.jpl.nasa.gov/emit/
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Summary of the Second OMI–TROPOMI Science Team Meeting
Introduction
The second joint Ozone Monitoring Instrument (OMI)–TROPOspheric Monitoring Instrument (TROPOMI) Science Team (ST) meeting was held June 3–6, 2024. The meeting used a hybrid format, with the in-person meeting hosted at the National Center for Atmospheric Research (NCAR) in Boulder, CO. This was the first OMI meeting to offer virtual participation since the COVID-19 travel restrictions. Combining the onsite and virtual attendees, the meeting drew 125 participants – see Photo.
OMI flies on NASA’s Earth Observing System (EOS) Aura platform, launched July 15, 2004. TROPOMI flies on the European Space Agency’s (ESA)–Copernicus Sentinel-5 Precursor platform. OMI has collected nearly 20 years of data and TROPOMI now has amassed 5 years of data.
Meeting content was organized around the following four objectives:
discussion of the final reprocessing of OMI data (called Collection 4) and of data preservation; discussion of OMI data continuity and enhancements using TROPOMI measurements; development of unique TROPOMI products [e.g., methane (CH4)], applications (e.g., tracking emissions – and using them as indicators of socioeconomic and military activities), and new focus regions (e.g., Africa); and leverage synergies between atmospheric composition (AC) and greenhouse gas (GHG) missions, which form the international constellation of low Earth orbit (LEO) and geostationary orbit (GEO) satellites. The remainder of this article summarizes the highlights from each day of the meeting.
Photo. Group photo of the in-person participants at the OMI–TROPOMI Science Team meeting. Photo credit: Shaun Bush/NCAR’s Atmospheric Chemistry Observations & Modeling DAY ONE
The topics covered on the first day of the meeting included OMI instrument performance, calibration, final Collection 4 reprocessing, and plans for data preservation.
OMI and Data Products Update
Pieternel Levelt [Royal Netherlands Meteorological Institute (KNMI)—OMI Principal Investigator (PI) and NCAR’s Atmospheric Chemistry Observations & Modeling (ACOM) Laboratory—Director] began her presentation by dedicating the meeting to the memory of Johan de Vries, whose untimely death came as a shock to the OMI and TROPOMI teams – see In Memoriam: Johan de Vries for a celebration of his accomplishments and contributions to the OMI-TROPOMI team. She then went on to give a status update on OMI, which is one of two currently operating instruments on EOS Aura [the other being the Microwave Limb Sounder (MLS)]. OMI is the longest operating and stable ultraviolet–visible (UV-VIS) spectrometer. It continues to “age gracefully” thanks to its design, contamination control measures undertaken after the launch, and stable optical bench temperature. Lessons learned during integration of OMI on the Aura spacecraft (e.g., provide additional charged couple device shielding) and operations (i.e., monitor partial Earth-view port blockages) guided the development and operations of the follow-on TROPOMI mission.
Continued monitoring of OMI performance is crucial for extending science- and trend-quality OMI records to the end of the Aura mission (currently expected in 2026). Antje Ludewig [KNMI] described the new OMI Level-1B (L1B) processor (Collection 4), which is based on TROPOMI data flow and optimized calibrations. The processor has been transferred to the U.S. OMI ST, led by Joanna Joiner [NASA’s Goddard Space Flight Center (GSFC)]. Matthew Bandel [Science Systems and Applications, Inc. (SSAI)] described NASA’s new OMI monitoring tools.
Sergey Marchenko [SSAI] discussed OMI daily spectral solar irradiance (SSI) data, which are used for monitoring solar activity and can be compared with the dedicated Total and Spectral Solar Irradiance Sensor (TSIS-1) on the International Space Station. Continuation of OMI measurements will allow comparisons with the upcoming NASA TSIS-2 mission. Antje Inness [European Centre for Medium-range Weather Forecasts (ECMWF)] described operational assimilation of OMI and TROPOMI near-real time data into the European Copernicus Atmosphere Monitoring Service (CAMS) daily analysis/forecast and re-analysis – see Figure 1.
In Memoriam: Johan de Vries
Johan de Vries
June 10, 1956 – May 8, 2024 Johan de Vries [Airbus Netherlands—Senior Specialist Remote Sensing] passed away suddenly on May 8, 2024, after a distinguished career. As a member of the Ozone Monitoring Instrument (OMI)–TROPOspheric Monitoring Instrument (TROPOMI) program, Johan conceptualized the idea of using a two-dimensional (2D) charged couple detector (CCD) for the OMI imaging spectrometer. This “push-broom” design led to high-spatial resolution spectra combined with high-spatial resolution and daily global coverage capability. His pioneering design for OMI has now been repeated on several other U.S. and international atmospheric composition measuring instruments – in both low and geostationary orbits – that are either in orbit or planned for launch soon. This achievement ensures that Johan’s legacy will live on for many years to come as these push-broom Earth observing spectrometers result in unprecedented data for environmental research and applications. The OMI and TROPOMI teams express their deepest condolences to de Vries family and colleagues over this loss.
Figure 1. An example of TROPOMI pixel nitrogen dioxide (NO2) observations over Europe on September 8, 2018 [top] and the corresponding super observations [bottom] for a model grid of 0.5 x 0.5o. Cloudy locations are colored grey. TROPOMI super observations are tested for use in the European Centre for Medium Range Weather Forecasting (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) data assimilation framework and will also be used for combined OMI–TROPOMI gridded datasets. Figure credit: reprinted from a 2024 paper posted on EGUSphere. Updates on OMI and TROPOMI Level-2 Data Products
The U.S. and Netherlands OMI STs continue to collaborate closely on reprocessing and improving OMI and TROPOMI L2 science products. During the meeting, one or more presenters reported on each product, which are described in the paragraphs that follow.
Serena Di Pede [KNMI] discussed the latest algorithm updates to the Collection 4 OMI Total Column Ozone (O3) product, which is derived using differential absorption spectroscopy (DOAS). She compared results from the new algorithm with the previous Collection 3 and with both the TROPOMI and OMI NASA O3 total column (Collection 3) algorithms. Collection 4 improved on previous versions by reducing the retrieval fit error and the along-track stripes of the product.
Juseon “Sunny” Bak and Xiong Liu [both from Smithsonian Astrophysical Observatory (SAO)] gave updates on the status of the Collection 4 O3 profile products.
Lok Lamsal [GSFC/University of Maryland, Baltimore County (UMBC)] and Henk Eskes [KNMI] compared Collection 3 and Collection 4 of the nitrogen dioxide (NO2) products.
Zolal Ayzpour [SAO] discussed the status of the OMI Collection 4 formaldehyde (HCHO) product.
Hyeong-Ahn Kwon [SAO] presented a poster that updated the Glyoxal product.
Omar Torres [GSFC] and Changwoo Ahn [GSFC/SSAI] presented regional trend analyses using the re-processed OMI Collection 4 absorbing aerosol product – see Figure 2.
Figure 2. Reprocessed OMI records (from Collection 4) of monthly average aerosol optical depth (AOD) at 388 nm derived from the OMI aerosol algorithm (OMAERUV) over Western North America (WNA): 30°N–50°N, 110°W–128°W) [top] and over Eastern China (EC): 25°N–43°N, 112°E–124°E) [bottom]. A repeatable annual cycle over WNA occurred with autumn minimum at around 0.1 and a spring maximum in the vicinity of 0.4 during the 2005–2016 period. After 2017 much larger AOD maxima in the late summer are associated with wildfire smoke occurrence. Over EC (bottom) the 2005–2014 AOD record depicts a large spring maxima (0.7 and larger) due to long-range transport of dust and secondary pollution aerosols followed by late autumn minima (around 0.3). A significant AOD decrease is observed starting in 2015 with reduced minimum and maximum values to about 0.2 and 0.5 respectively. The drastic change in AOD load over this region is associated with pollution control measures enacted over the last decade. Figure credit: Changwoo Ahn/GSFC/SSAI and Omar Torres/GSFC Updates on EOS Synergy Products
Several presenters and posters during the meeting gave updates on EOS synergy products, where OMI data are combined with data from another instrument on one of the EOS flagships. These are described below.
Brad Fisher [SSAI] presented a poster on the Joint OMI–Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products.
Wenhan Qin [GSFC/SSAI] presented a poster on the MODIS–OMI Geometry Dependent Lambertian Equivalent Surface Reflectivity (GLER) product.
Jerry Ziemke [GSFC and Morgan State University (MSU)] presented on the OMI–MLS Tropospheric Ozone product that showed post-COVID tropospheric O3 levels measured using this product, which are consistent with similar measurements obtained using other satellite O3 data – see Figure 3.
Figure 3. Anomaly maps of merged tropospheric column O3 (TCO) satellite data (Dobson Units) for spring–summer 2020–2023. In this context, an anomaly is defined as deseasonalized O3 data. The anomaly maps are derived by first calculating seasonal climatology maps for 2016–2019 (i.e., pre-COVID pandemic) and then subtracting these climatology maps from the entire data record.
Note: The sensors used in this analysis include: the Ozone Mapping and Profiler Suite (OMPS)/ Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) and Cross-track Infrared Sounder (CrIS) on the Joint Polar Satellite System (JPSS) missions, which currently include the joint NASA–NOAA Suomi National Polar-orbiting Partnership (Suomi NPP), NOAA-20, and NOAA-21; the Earth Polychromatic Imaging Camera (EPIC)/MERRA-2 on the Deep Space Climate Observatory (DSCOVR); the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS), both on EOS Aura; the Infrared Atmospheric Sounding Interferometer (IASI)/ Fast Optimal Retrievals on Layers (FORLI), IASI/SOftware for Fast Retrievals of IASI Data (SOFRID), and IASI/Global Ozone Monitoring Experiment–2 (GOME2). IASI flies on the European MetOp-A, -B, and -C missions. The OMPS/MERRA-2 and EPIC/MERRA-2 products subtract coincident MERRA-2 stratospheric column O3 from total O3 to derive tropospheric column O3. Figure credit: Jerry Ziemke/GSFC and Morgan State University (MSU) Updates on Multisatellite Climate Data Records
The OMI ST also discussed refining and analyzing multisatellite climate data records (CDRs) that have been processed with consistent algorithms. Several presenters reported on this work, who are mentioned below.
Jenny Stavrakou [Koninklijk Belgisch Instituut voor Ruimte-Aeronomie, Royal Belgian Institute for Space Aeronomy (BIRA–IASB)], reported on work focusing on the OMI and TROPOMI HCHO CDR and Huan Yu [BIRA–IASB)] reported harmonized OMI and TROPOMI cloud height datasets based on improved O2-O2 absorption retrieval algorithm.
Lok Lamsal [GSFC/UMBC, Goddard Earth Sciences Technology and Research (GESTAR) II], Henk Eskes, and Pepijn Veefkind [KNMI] reported on the OMI and TROPOMI NO2 CDRs – see Figure 4.
Si-Wan Kim [Yonsei University, South Korea] reported on OMI and TROPOMI long-term NO2 trends.
Figure 4. OMI nitrogen dioxide (NO2) time series bridging the first GOME mission (which flew on the European Remote Sensing Satellite–2 (ERS–2) from 1995–2011 with limited coverage after 2003) and measurements from the two currently operating missions – OMI (2004–present) and TROPOMI (2017–present) – offer consistent climate data records that allow for studying long-term changes. This example shows tropospheric NO2 column time series from three instruments over Phoenix, AZ. The overlap between the OMI and TROPOMI missions allows for intercomparison between the two, which is crucial to avoid continuity-gaps in multi-instrument time series. The ERS-2 (GOME) had a morning equator crossing time (10:30 AM), while Aura (OMI) and Metop (TROPOMI) have afternoon equator crossing times of 1:45 PM and 1:30 PM respectively. Figure credit: Lok Lamsal/GSFC/University of Maryland, Baltimore County (UMBC) Update on Aura’s Drifting Orbit
Bryan Duncan [GSFC—Aura Project Scientist] closed out the first day with a presentation summarizing predictions of Aura’s drifting orbit. Overall, the impact of Aura’s drift is expected to be minor, and the OMI and MLS teams will be able to maintain science quality data for most data products. He thanked the OMI/TROPOMI ST and user community for expressing their strong support for continuing Aura observations until the end of the Aura mission in mid–2026.
DAY TWO
The second day of the meeting focused on current and upcoming LEO and GEO Atmospheric Composition (AC) missions.
TROPOMI Mission and Data Product Updates
Veefkind presented an update on the TROPOMI mission, which provides continuation and enhancements for all OMI products. Tobias Borssdorf [Stichting Ruimte Onderzoek Nederland (SRON), or Netherlands Institute for Space Research] explained how TROPOMI, with its innovative shortwave infrared (SWIR) spectrometer, measures CH4 and carbon monoxide (CO). This approach continues measurements that began by the Measurements of Pollution in the Troposphere (MOPITT) instrument on Terra.
Hiren Jethva [NASA Airborne Science Program] and Torres presented new TROPOMI near-UV aerosol products, including a new aerosol layer optical centroid height product, which takes advantage of the TROPOMI extended spectral range – see Figure 5.
Figure 5. Global gridded (0.10° x 0.10°) composite map of aerosol layer optical centroid height (AH) retrieved from TROPOMI O2-B band observations from May–September 2023. Figure credit: Hiren Jethva/NASA Airborne Science Program GEMS–TEMPO–Sentinel-4 (UVN): A Geostationary Air Quality Constellation
TROPOMI global observations serve as a de facto calibration standard used to homogenize a new constellation of three missions that will provide AC observations for most of the Northern Hemisphere from GEO. Two of the three constellation members are already in orbit. Jhoon Kim [Yonsei University—PI] discussed the Geostationary Environmental Monitoring Spectrometer (GEMS), launched on February 19, 2020 aboard the Republic of Korea’s GEO-KOMPSAT-2B satellite. It is making GEO AC measurements over Asia. The GEMS team is working on validating measurements of NO2 diurnal variations using ground-based measurements from the PANDORA Global Network over Asia and aircraft measurements from the ASIA–AQ field campaign.
Liu discussed NASA’s Tropospheric Emission Monitoring of Pollution (TEMPO) spectrometer, launched on April 7, 2023, aboard a commercial INTELSAT 40E satellite. From its GEO vantage point, TEMPO can observe the Continental U.S., Southern Canada, Mexico, and the coastal waters of the Northwestern Atlantic and Northeastern Pacific oceans.
Gonzales Abad [SAO] presented the first measurements from TEMPO. He explained that TEMPO’s design is similar to GEMS, but GEMS includes an additional visible and near infrared (VNIR) spectral channel (540–740 nm) to measure tropospheric O3, O2, and water vapor (H2Ov). TEMPO can perform optimized morning scans, twilight scans, and scans with high temporal resolution (5–10 minutes) over selected regions. Abad reported that the TEMPO team released L1B spectra and the first provisional public L2 products (Version 3), including NO2, HCHO, and total column O3. Andrew Rollins [National Oceanic and Atmospheric Administration’s (NOAA) Chemical Sciences Laboratory (CSL)] reported that the TEMPO team is working on validation of provisional data using both ground-based data from PANDORA spectrometers and data collected during several different airborne campaigns completed during the summer of 2023 and compiled on the AGES+ website.
Ben Veihelmann [ESA’s European Space Research and Technology Center—PI] explained that ESA’s Copernicus Sentinel-4 mission will be the final member of the GEO AC constellation. Veefkind summarized the Sentinel-4 mission, which is expected to launch on the Meteosat Third Generation (MTG)-Sounder 1 (MTG-S1) platform in 2025. The mission is dedicated to measuring air quality and O3 over Europe and parts of the Atlantic and North Africa. Sentinel-4 will deploy the first operational UV-Vis-NIR (UVN) imaging spectrometer on a geostationary satellite. (Airbus will build UVN, with ESA providing guidance.) Sentinel-4 includes two instruments launched in sequence on MTG-S1 and MTG-S2 platforms designed to have a combined lifetime of 15 years. The mission by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) will operate Sentinel-4, and the Deutsches Zentrum für Luft- und Raumfahrt (DLR) or German Aerospace Center will be responsible for operational L2 processing.
These three GEO AC missions, along with the upcoming ESA/EUMETSAT/Copernicus LEO (morning orbit, 9:30 a.m.) Sentinel-5 (S5) mission, will complete a LEO–GEO satellite constellation that will enable monitoring of the most industrialized and polluted regions in the Northern Hemisphere into the 2030s. Sentinel-5 will not continue the OMI–TROPOMI data record in the early afternoon; however, it will be placed in the morning orbit and follow ESA’s Global Ozone Monitoring Experiment (GOME) and EUMETSAT GOME-2 missions. By contrast, GEO AC observations over the Southern Hemisphere are currently not available. Several presenters described ongoing projects for capacity building for LEO satellite air quality data uptake and emission monitoring in Africa and advocated for the new geostationary measurements.
Synergy with Other Current or Upcoming Missions
Attendees discussed the synergy between upcoming AC, GHG, and ocean color missions. Current trends in satellite AC measurements are toward increased spatial resolution and combined observations of short-lived reactive trace gases – which are important for air quality (AQ) monitoring – and long-lived GHG – which are important for climate monitoring and carbon cycle assessments. Some trace gases (e.g., O3 and CH4) are both polluters and GHG agents. Others [e.g., NO2 and sulfur dioxide (SO2 )] are aerosol [particulate matter (PM)] and O3 precursors and are used as proxies and spatial indicators for anthropogenic CO2 and CH4 emissions.
Yasjka Meijer [ESA—Copernicus Anthropogenic Carbon Dioxide Monitoring (CO2M) Mission Scientist]) reviewed the plans for CO2M, which includes high-resolution measurements [~4 km2 (~1.5 mi2)] of CO2 , CH4 , and NO2.
Jochen Landgraf [SRON] described ESA’s new Twin Anthropogenic Greenhouse Gas Observers (TANGO) mission, which has the objective to measure CO2 , CH4 , and NO2 at even higher spatial resolution [~300 m (~984 ft)] using two small CubeSat spectrometers flying in formation.
Hiroshi Tanimoto [National Institute for Environmental Studies, Japan] described the Japan Aerospace Exploration Agency’s (JAXA) Global Observing SATellite for greenhouse gases and water cycle (GOSAT-GW) mission, which includes the Total Anthropogenic and Natural Emission mapping SpectrOmeter (TANSO-3) spectrometer to simultaneously measure CO2 , CH4, and NO2 with ~1–3 km (~0.6–1.8 mi) spatial resolution in focus mode. GOSAT-GW will also fly the Advanced Microwave Scanning Radiometer 3 (AMSR3).
Joanna Joiner [GSFC—Geostationary Extended Operations (GeoXO) Project Scientist and ACX Instrument Scientist] described the plans for the next-generation U.S. geosynchronous satellite constellation, which will consist of three satellites covering the full Earth disk: GEO-East, GEO-West, and GEO-Central. (By contrast, the current Geostationary Operational Environmental Satellite (GOES) series has two satellites: GOES–East and GOES–West.) GEO-Central will carry an advanced infrared sounder (GXS) for measuring vertical profiles of many trace gases, temperature and humidity, and a new UV-VIS spectrometer (ACX), which is a follow-on to TEMPO for AQ applications. Both GXS and ACX instruments will be built by BAE Systems, which acquired Ball Aerospace and Technology, and will also build the GeoXO ocean color spectrometer (OCX).
Andrew Sayer [UMBC] described NASA’s Plankton, Aerosols, Clouds, and ocean Ecosystem (PACE), which launched on February 8, 2024. The PACE payload includes a high-spatial resolution [~1 km (~0.6 mi) at nadir] Ocean Color Instrument (OCI), which is a UV-Vis-NIR spectrometer with discrete SWIR bands presenting additional opportunities for synergistic observations with the AC constellation. Sayer presented OCI “first light” aerosol data processed using the unified retrieval algorithm developed by Lorraine Remer [UMBC].
The second day concluded with a joint crossover session with NASA’s Health and Air Quality Applied Sciences Team (HAQAST) followed by a poster session. Several OMI–TROPOMI STM participants presented on a variety of topics that illustrate how OMI and TROPOMI data are being used to support numerous health and AQ applications. Duncan, who is also a member of HAQAST team, presented “20 years of health and air quality applications enabled by OMI data.” He highlighted OMI contributions to AQ and health applications, including NO2 trend monitoring, inferring trends of co-emitted species [e.g., CO2, CO, some Volatile Organic Compounds (VOCs)], validation of new satellite missions (e.g., TEMPO, PACE), and burden of disease studies.
DAY THREE
Discussions on the third day focused on advanced retrieval algorithms, leading to new products and new applications for OMI and TROPOMI data. Several presentations described applications of TROPOMI CH4 data and synergy with small satellites.
Advanced Retrieval Algorithms and New Data Products
Ilse Aben [SRON] described TROPOMI global detection of CH4 super-emitters using an automated system based on Machine Learning (ML) techniques – see Figure 6. Berend Schuit [SRON] provided additional detail on these methods. He introduced the TROPOMI CH4 web site to the meeting participants. He explained how TROPOMI global CH4 measurements use “tip-and-cue” dedicated satellites with much higher spatial resolution instruments [e.g., GHGSat with ~25-m (~82-ft) resolution] to scan for individual sources and estimate emission rates. Most CH4 super-emitters are related to urban areas and/or landfills, followed by plumes from gas and oil industries and coal mines.
Figure 6. Methane plume map produced by SRON shows TROPOMI large CH4 emission plumes for the week of the OMI–TROPOMI meeting (June 3–6, 2024). Figure credit: Itse Aben/Stichting Ruimte Onderzoek Nederland (SRON) Alba Lorente [Environmental Defense Fund—Methane Scientist] introduced a new MethaneSAT satellite launched in March 2024, which aims to fill the gap in understanding CH4 emissions on a regional scale [200 x 200 km2 (~77 x 77 mi2)] from at least 80% of global oil and gas production, agriculture, and urban regions. Alex Bradley [University of Colorado, Boulder] described improvements to TROPOMI CH4 retrievals that were achieved by correcting seasonal effects of changing surface albedo.
Daniel Jacob [Harvard University] presented several topics, including the highest resolution [~30 m (~98 ft)] NO2 plume retrievals from Landsat-8 – see Figure 7 – and Sentinel-2 imagers. He also discussed using a ML technique trained with TROPOMI data to improve NO2 retrievals from GEMS and modeling NO2 diurnal cycle and emission estimates. He introduced the ratio of ammonia (NH3) to NO2 (NH3/NO2) as an indicator of particulate matter with diameters less than 2.5 µm (PM2.5) nitrate sensitivity regime. Jacob emphasized the challenges related to satellite NO2 retrievals (e.g., accounting for a free-tropospheric NO2 background and aerosols).
Figure 7. Landsat Optical Land Imager (OLI) image, obtained on October 17, 2021 over Saudi Arabia, shows power plant exhaust, which contains nitrogen dioxide (NO2) drifting downwind from the sources (the two green circles are the stacks). The ultra-blue channel (430–450 nm) on OLI enables quantitative detection of NO2 in plumes from large point sources at 30-m (~98-ft) resolution. This provides a unique ability for monitoring point-source emissions of oxides of nitrogen (NOx). The two stacks in the image are separated by 2 km (~1.2 mi). Figure credit: Daniel Jacob – repurposed from a 2024 publication in Proceedings of the National Academies of Sciences (PNAS) Steffen Beirle [Max Planck Institute for Chemistry, Germany] explained his work to fit TROPOMI NO2 column measurements to investigate nitric oxide (NO) to NO2 processing in power plant plumes. Debra Griffin [Environment and Climate Change Canada (ECCC)] used TROPOMI NO2 observations and ML random forest technique to estimate NO2 surface concentrations. Sara Martinez-Alonso [NCAR] investigated geographical and seasonal variations in NO2 diurnal cycle using GEMS and TEMPO data. Ziemkecombined satellite O3 data to confirm a persistent low anomaly (~5–15%) in tropospheric O3 after 2020. Jethva presented advanced OMI and TROPOMI absorbing aerosol products. Yu described improved OMI and TROPOMI cloud datasets using the O2-O2 absorption band at 477 nm. Nicholas Parazoo [Jet Propulsion Laboratory (JPL)] described TROPOMI Fraunhofer line retrievals of red solar-induced chlorophyll fluorescence (SIF) near O2-B band (663–685 nm) to improve mapping of ocean primary productivity. Liyin He [Duke University] described using satellite terrestrial SIF data to study the effect of particulate pollution on ecosystem productivity.
New Applications
Zachary Fasnacht [SSAI] used OMI and TROPOMI spectra to train a neural network to gap-fill MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) ocean color data under aerosol, sun glint, and partly cloudy conditions. This ML method can also be applied to PACE OCI spectra. Anu-Maija Sundström [Finnish Meteorological Institute (FMI)] used OMI and TROPOMI SO2 and O3 data as proxies to study new particle formation events. Lindsey Anderson [University of Colorado, Boulder] described how she used TROPOMI NO2 and CO measurements to estimate the composition of wildfire emissions and their effect on forecasted air quality. Heesung Chong [SAO] applied OMI bromine oxide (BrO) retrievals to the NOAA operational Ozone Mapping and Profiling Suite Nadir Mapper (OMPS-NM) on joint NOAA–NASA Suomi-National Polar-orbiting Partnership (Suomi NPP) satellite with the possibility to continue afternoon measurements using similar OMPS-NM instruments on the four Joint Polar Satellite System missions (JPSS-1,-2,-3,-4) into the 2030s. (JPSS-1 and -2 are now in orbit and known as NOAA-20 and -21 respectively; JPSS-4 is planned for launch in 2027, with JPSS-3 currently targeted for 2032.)
Kim demonstrated the potential for using satellite NO2 and SO2 emissions as a window into socioeconomic issues that are not apparent by other methods. For example, she showed how OMI and TROPOMI data were widely used to monitor air quality improvements in the aftermath of COVID-19 lockdowns. (Brad Fisher [SSAI] presented a poster on a similar topic.)
Cathy Clerbaux [Center National d’Études Spatiale (CNES), or French Space Agency] showed how her team used TROPOMI NO2 data to trace the signal emitted by ships and used this information to determine how the shipping lanes through the Suez Canal changed in response to unrest in the Middle East. Iolanda Ialongo [FMI] showed a similar drop of NO2 emissions over Donetsk region due to the war in Ukraine. Levelt showed how OMI and TROPOMI NO2 data are used for capacity-building projects and for air quality reporting in Africa. She also advocated for additional geostationary AQ measurements over Africa.
DAY FOUR
Discussions on the final day focused on various methods of assimilating satellite data into air quality models for emission inversions and aircraft TEMPO validation campaigns. The meeting ended with Levelt giving her unique perspective on the OMI mission, as she reflected on more than two decades being involved with the development, launch, operation, and maintenance of OMI.
Assimilating Satellite Data into Models for Emissions
Brian McDonald [CSL] described advance chemical data assimilation of satellite data for emission inversions and the GReenhouse gas And Air Pollutants Emissions System (GRA2PES). He showed examples of assimilations using TROPOMI and TEMPO NO2 observations to adjust a priori emissions. He also showed that when TEMPO data are assimilated, NOx emissions adjust faster and tend to perform better at the urban scale. Adrian Jost [Max Planck Institute for Chemistry] described the ESA-funded World Emission project to improve pollutant and GHG emission inventories using satellite data. He showed examples of TROPOMI SO2 emissions from large-point sources and compared the data with bottom-up and NASA SO2 emissions catalogue.
Ivar van der Velde [SRON] presented a method to evaluate fire emissions using new satellite imagery of burned area and TROPOMI CO. Helene Peiro [SRON] described her work to combine TROPOMI CO and burned area information to compare the impact of prescribed fires versus wildfires on air quality in the U.S. She concluded that prescribed burning reduces CO pollution. Barbara Dix [University of Colorado, Boulder, Cooperative Institute for Research in Environmental Sciences] derived NOx emissions from U.S. oil and natural gas production using TROPOMI NO2 data and flux divergence method. She estimated TROPOMI CH4 emissions from Denver–Julesburg oil and natural gas production. Dix explained that the remaining challenge is to separate oil and gas emissions from other co-located CH4 sources. Ben Gaubert [NCAR, Atmospheric Chemistry Observations and Modeling] described nonlinear and non-Gaussian ensemble assimilation of MOPITT CO using the data assimilation research testbed (DART).
Andrew (Drew) Rollings [CSL] presented first TEMPO validation results from airborne field campaigns in 2023 (AGES+ ), including NOAA CSL Atmospheric Emissions and Reactions observed from Megacities to Marine Aeras (AEROMMA) and NASA’s Synergistic TEMPO Air Quality Science (STAQS) campaigns.
A Reflection on Twenty Years of OMI Observations
Levelt gave a closing presentation in which she reflected on her first involvement with the OMI mission as a young scientist back in 1998. This led to a collaboration with the international ST to develop the instrument, which was included as part of Aura’s payload when it launched in July 2004. She reminisced about important highlights from 2 decades of OMI, e.g., the 10-year anniversary STM at KNMI in 2014 (see “Celebrating Ten Years of OMI Observations,” The Earth Observer, May–Jun 2014, 26:3, 23–30), and the OMI ST receiving the NASA/U.S. Geological Survey Pecora award in 2018 and the American Meteorological Society’s Special award in 2021.
Levelt pointed out that in this combined OMI–TROPOMI meeting the movement towards using air pollution and GHG data together became apparent. She ended by saying that the OMI instrument continues to “age gracefully” and its legacy continues with the TROPOMI and LEO–GEO atmospheric composition constellation of satellites that were discussed during the meeting.
Conclusion
Overall, the second OMI–TROPOMI STM acknowledged OMI’s pioneering role and TROPOMI’s unique enhancements in measurements of atmospheric composition:
Ozone Layer Monitoring: Over the past two decades, OMI has provided invaluable data on the concentration and distribution of O3 in the Earth’s stratosphere. This data has been crucial for understanding and monitoring the recovery of the O3 layer following international agreements, such as the Montreal Protocol. Air Quality Assessment: OMI’s high-resolution measurements of air pollutants, such as NO2, SO2, and HCHO, have significantly advanced our understanding of air quality. This information has been vital for tracking pollution sources, studying their transport and transformation, and assessing their impact on human health and the environment. Climate Research: The data collected by OMI has enhanced our knowledge of the interactions between atmospheric chemistry and climate change. These insights have been instrumental in refining climate models and improving our predictions of future climate scenarios. Global Impact: The OMI instrument has provided near-daily global coverage of atmospheric data, which has been essential for scientists and policymakers worldwide. The comprehensive and reliable data from OMI has supported countless research projects and informed decisions aimed at protecting and improving our environment. OMI remains one of the most stable UV/Vis instruments over its two decades of science and trend quality data collection. The success of the OMI and TROPOMI instruments is a testament to the collaboration, expertise, and dedication of both teams.
Nickolay Krotkov
NASA’s Goddard Space Flight Center
Nickolay.a.krotkov@nasa.gov
Pieternel Levelt
National Center for Atmospheric Research, Atmospheric Chemistry Observations & Modeling
levelt@ucar.edu
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Last Updated Nov 12, 2024 Related Terms
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