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By NASA
3 min read
Buckle Up: NASA-Funded Study Explores Turbulence in Molecular Clouds
This image shows the distribution of density in a simulation of a turbulent molecular cloud. NASA/E. Scannapieco et al (2024) On an airplane, motions of the air on both small and large scales contribute to turbulence, which may result in a bumpy flight. Turbulence on a much larger scale is important to how stars form in giant molecular clouds that permeate the Milky Way.
In a new NASA-funded study in the journal Science Advances, scientists created simulations to explore how turbulence interacts with the density of the cloud. Lumps, or pockets of density, are the places where new stars will be born. Our Sun, for example, formed 4.6 billion years ago in a lumpy portion of a cloud that collapsed.
“We know that the main process that determines when and how quickly stars are made is turbulence, because it gives rise to the structures that create stars,” said Evan Scannapieco, professor of astrophysics at Arizona State University and lead author of the study. “Our study uncovers how those structures are formed.”
Giant molecular clouds are full of random, turbulent motions, which are caused by gravity, stirring by the galactic arms and winds, jets, and explosions from young stars. This turbulence is so strong that it creates shocks that drive the density changes in the cloud.
The simulations used dots called tracer particles to traverse a molecular cloud and travel along with the material. As the particles travel, they record the density of the part of the cloud they encounter, building up a history of how pockets of density change over time. The researchers, who also included Liubin Pan from Sun Yat Sen University in China, Marcus Brüggen from the University of Hamburg in Germany, and Ed Buie II from Vassar College in Poughkeepsie, New York, simulated eight scenarios, each with a different set of realistic cloud properties.
This animation shows the distribution of density in a simulation of a turbulent molecular cloud. The colors represent density, with dark blue indicating the least dense regions and red indicating the densest regions. Credit: NASA/E. Scannapieco et al (2024) The team found that the speeding up and slowing down of shocks plays an essential role in the path of the particles. Shocks slow down as they go into high-density gas and speed up as they go into low-density gas. This is akin to how an ocean wave strengthens when it hits shallow water by the shore.
When a particle hits a shock, the area around it becomes more dense. But because shocks slow down in dense regions, once lumps become dense enough, the turbulent motions can’t make them any denser. These lumpiest high-density regions are where stars are most likely to form.
While other studies have explored molecular cloud density structures, this simulation allows scientists to see how those structures form over time. This informs scientists’ understanding of how and where stars are likely to be born.
“Now we can understand better why those structures look the way they do because we’re able to track their histories,” said Scannapieco.
This image shows part of a simulation of a molecular cloud. The colors represent density, with dark blue indicating the least dense regions and red indicating the densest regions. Tracer particles, represented by black dots, traverse the simulated cloud. By examining how they interact with shocks and pockets of density, scientists can better understand the structures in molecular clouds that lead to star formation. NASA/E. Scannapieco et al (2024) NASA’s James Webb Space Telescope is exploring the structure of molecular clouds. It is also exploring the chemistry of molecular clouds, which depends on the history of the gas modeled in the simulations. New measurements like these will inform our understanding of star formation.
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By European Space Agency
With the initial images from each of the instruments aboard ESA’s EarthCARE satellite now in hand, it's time to reveal how these four advanced sensors work in synergy to measure exactly how clouds and aerosols influence the heating and cooling of our atmosphere.
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By NASA
Earth (ESD)Earth Home Explore Climate Change Science in Action Multimedia Data For Researchers 4 min read
Via NASA Plane, Scientists Find New Gamma-ray Emission in Storm Clouds
Tropical thunderstorm with lightning, near the airport of Santa Marta, Colombia. Credit: Oscar van der Velde There’s more to thunderclouds than rain and lightning. Along with visible light emissions, thunderclouds can produce intense bursts of gamma rays, the most energetic form of light, that last for millionths of a second. The clouds can also glow steadily with gamma rays for seconds to minutes at a time.
Researchers using NASA airborne platforms have now found a new kind of gamma-ray emission that’s shorter in duration than the steady glows and longer than the microsecond bursts. They’re calling it a flickering gamma-ray flash. The discovery fills in a missing link in scientists’ understanding of thundercloud radiation and provides new insights into the mechanisms that produce lightning. The insights, in turn, could lead to more accurate lightning risk estimates for people, aircraft, and spacecraft.
Researchers from the University of Bergen in Norway led the study in collaboration with scientists from NASA’s Marshall Space Flight Center in Huntsville, Alabama, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland, the U.S. Naval Research Laboratory, and multiple universities in the U.S., Mexico, Colombia, and Europe. The findings were described in a pair of papers in Nature, published Oct. 2.
The international research team made their discovery while flying a battery of detectors aboard a NASA ER-2 research aircraft. In July 2023, the ER-2 set out on a series of 10 flights from MacDill Air Force Base in Tampa, Florida. The plane flew figure-eight flight patterns a few miles above tropical thunderclouds in the Caribbean and Central America, providing unprecedented views of cloud activity.
The scientific payload was developed for the Airborne Lightning Observatory for Fly’s Eye Geostationary Lightning Mapper Simulator and Terrestrial Gamma-ray Flashes (ALOFT) campaign. Instrumentation in the payload included weather radars along with multiple sensors for measuring gamma rays, lightning flashes, and microwave emissions from clouds.
NASA’s high-flying ER-2 airplane carries instrumentation in this artist’s impression of the ALOFT mission to record gamma rays (colored purple for illustration) from thunderclouds.Credit: NASA/ALOFT team The researchers had hoped ALOFT instruments would observe fast radiation bursts known as terrestrial gamma-ray flashes (TGFs). The flashes, first discovered in 1992 by NASA’s Compton Gamma Ray Observatory spacecraft, accompany some lightning strikes and last only millionths of a second. Despite their high intensity and their association with visible lightning, few TGFs have been spotted during previous aircraft-based studies.
“I went to a meeting just before the ALOFT campaign,” said principal investigator Nikolai Østgaard, a space physicist with the University of Bergen. “And they asked me: ‘How many TGFs are you going to see?’ I said: ‘Either we’ll see zero, or we’ll see a lot.’ And then we happened to see 130.”
However, the flickering gamma-ray flashes were a complete surprise.
“They’re almost impossible to detect from space,” said co-principal investigator Martino Marisaldi, who is also a University of Bergen space physicist. “But when you are flying at 20 kilometers [12.5 miles] high, you’re so close that you will see them.” The research team found more than 25 of these new flashes, each lasting between 50 to 200 milliseconds.
The abundance of fast bursts and the discovery of intermediate-duration flashes could be among the most important thundercloud discoveries in a decade or more, said University of New Hampshire physicist Joseph Dwyer, who was not involved in the research. “They’re telling us something about how thunderstorms work, which is really important because thunderstorms produce lightning that hurts and kills a lot of people.”
More broadly, Dwyer said he is excited about the prospects of advancing the field of meteorology. “I think everyone assumes that we figured out lightning a long time ago, but it’s an overlooked area … we don’t understand what’s going on inside those clouds right over our heads.” The discovery of flickering gamma-ray flashes may provide crucial clues scientists need to understand thundercloud dynamics, he said.
Turning to aircraft-based instrumentation rather than satellites ensured a lot of bang for research bucks, said the study’s project scientist, Timothy Lang of NASA’s Marshall Space Flight Center in Huntsville, Alabama.
“If we had gotten one flash, we would have been ecstatic — and we got well over 100,” he said. This research could lead to a significant advance in our understanding of thunderstorms and radiation from thunderstorms. “It shows that if you have the right problem and you’re willing to take a little bit of risk, you can have a huge payoff.”
By James Riordon
NASA’s Earth Science News Team
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Last Updated Oct 02, 2024 EditorJenny MarderContactJames RiordonLocationMarshall Space Flight Center Related Terms
Earth Gamma Rays Goddard Space Flight Center View the full article
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By NASA
9 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The Atmospheric Aerosols group, from the 2024 Student Airborne Research Program (SARP) West Coast cohort, poses in front of the natural sciences building at UC Irvine, during their final presentations on August 12, 2024. NASA Ames/Milan Loiacono Faculty Advisors: Dr. Andreas Beyersdorf, California State University, San Bernardino & Dr. Ann Marie Carlton, University of California
Graduate Mentor: Madison Landi, University of California, Irvine
Madison Landi, Graduate Mentor
Madison Landi, graduate student mentor for the 2024 SARP Aerosols group, provides an introduction for each of the group members and shares behind-the scenes moments from the internship.
Maya Niyogi
A Comparative Analysis of Tropospheric NO2: Evaluating TEMPO Satellite Data Against Airborne Measurements
Maya Niyogi, Johns Hopkins University
Nitrogen dioxide (NO2) plays a major role in atmospheric chemical reactions; the inorganic compound both contributes to tropospheric ozone production and reacts with volatile organic compounds to create health-hazardous particulate matter. The presence of NO2 in the atmosphere is largely due to anthropogenic activity, making NO2 at the forefront of policy decisions and scientific monitoring. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite launched in 2023 with the goal of monitoring pollution across North America. The publicly-accessible data became available for use in May 2024, however parts of the data remain unvalidated and in beta, creating a need for an in situ validation of its data products. Here we analyze TEMPO’s tropospheric NO2 measurements and compare them to aloft NO2 measurements collected during the NASA Student Airborne Research Project (SARP) 2024 airborne campaign. Six of the campaign flights recording NO2 performed a vertical spiral, providing vertical column data that was adjusted to ambient conditions for comparison against the corresponding TEMPO values. Statistical analyses indicate we have reasonable evidence to conclude that TEMPO satellite data and the flight-collected data record similar values. This research fills a critical knowledge gap through the utilization of aloft NO2 measurements to validate NASA’s newly-launched TEMPO satellite. It is expected that future users of TEMPO data can apply these results to better inform project creation and research.
Benjamin Wells
Investigating the Atmospheric Burden of Black Carbon Over the Past Decade in the Los Angeles Basin
Benjamin Wells, San Diego State University
Black Carbon is a primary aerosol emitted directly into the atmosphere as a result of biomass burning and incomplete combustion of fossil fuels. During the pre-industrial revolution, the main source of black carbon was natural sources whereas currently, the main source is anthropogenic activities. When black carbon is released into the atmosphere, it is a dominant absorber of solar radiation and leads to a significant warming effect on Earth’s climate. In addition to its harmful effects associated with climate change, ambient black carbon inhalation is correlated with adverse health effects such as respiratory and cardiovascular disease, cancer, and premature mortality. In this study, we analyze aloft black carbon measurements in 2016 and 2024 acquired on NASA SARP research flights and compare these concentrations to black carbon measurements taken during the 2010 CalNex field campaign. Both field campaigns flew similar flight paths over the Los Angeles basin allowing us to conduct a critical comparative analysis on vertical and spatial profiles of the atmospheric burden of black carbon over the past 14 years. During the CalNEX study, mass concentrations of black carbon ranged from 0.02 μg/m3 to 0.531 μg/m3, meanwhile 2024 SARP measurements demonstrate concentrations as elevated as 7.83 μg/m3 within the same region. Moreover, similar flight paths conducted during SARP 2024 and 2016 allow for further analysis of aloft black carbon concentrations over a period of time. The results of this study examines and analyzes the changing spatial and temporal characteristics of black carbon throughout the years, leading to an increase of adverse effects on both the climate and public health.
Devin Keith
Tracking Methane and Aerosols in relation to Health Effects in the San Joaquin Valley
Devin Keith, Mount Holyoke College
The San Joaquin Valley (SJV) is located in central California and is one of the most productive agricultural regions in the country for dairy, nuts, and berries, producing more than half of California’s $42 billion output. Due to the SJV’s close proximity to the Sierra Nevada Mountain Range to the East and predominantly Easterly winds, air pollution often accumulates because it is trapped by the geography. Significant chemical constituents of trapped particulate matter are ammonium (NH4), chloride (Cl), sulfate (SO4), nitrate (NO3), black carbon, and organic carbon. The particle size measured in this study is less than 1 micron in diameter, and due to their size, can easily penetrate the respiratory tract leading to adverse health effects such as: asthma, chronic obstructive pulmonary disease, and cardiovascular disease. We employ airborne data collected during the SARP 2024 mission onboard NASA’s P-3 research plane to observe spatial and temporal trends of NH4, Cl, SO4, NO3, and black carbon. Further, we analyze measurements from SARP 2016 flights and compare the atmospheric burden of pollution in the SJV across time. To investigate observations in the context of the public health impacts, we utilize data collected by the California Office of Environmental Health Hazards Assessment and find asthma and cardiovascular disease rates are higher in the SJV hotspots identified here. Per capita health impacts are greater than other California regions such as Los Angeles and San Francisco. The SJV exhibits higher rates of poverty than other communities, which may reveal an environmental justice issue that is difficult to explicitly quantify especially where measurements are sparse.
Lily Lyons
Investigating the Effects of Aerosols on Photosynthesis Using Satellite Imaging
Lily Lyons, Brandeis University
Aerosols in the atmosphere can affect the way sunlight travels to the ground by absorbing or scattering light. Sunlight is a critical component in plant photosynthesis, and the way light scatters affects productivity for vegetation and plant growth. When plants absorb sunlight, the chlorophyll in their leaves releases the excess energy as infrared light, which can be measured from space via satellite. To better understand how aerosol loading in the atmosphere affects plant photosynthesis, this study examines locations in Yosemite, Sequoia, Garrett, and Talladega national forests, and compares aerosol optical depth (AOD), normalized difference vegetation index (NDVI), and solar induced fluorescence (SIF) in these areas. Yosemite and Sequoia act as proxies for the old growth sequoia grove ecosystems, and Talladega and Garrett act as proxies for the Appalachian mixed mesophytic forest ecosystem. Our results show that within 2015-2020 during July, SIF and NDVI levels are significantly greater in mixed mesophytic forests than in sequoia groves. Using linear regression plots, we determined the correlation between SIF, NDVI and AOD to be weak in the given locations. Greater SIF in mixed mesophytic forests could suggest that the presence of a prominent and biodiverse understory is positive for the overall primary productivity of an ecosystem. This study is a good starting point for analyzing diverse ecosystems using SIF, NDVI and satellite data as proxies for photosynthesis, and broadening the scope of biomes examined for their SIF. Furthermore, it highlights the need for further investigation of aerosol impact on the trajectory and amount of sunlight that reaches certain plants.
Ryleigh Czajkowski
Validating the Performance of CMAQ in Simulating the Vertical Distribution of Trace Gases
Ryleigh Czajkowski, South Dakota School of Mines and Technology
Air quality modeling simulates atmospheric processes and air pollutant transport to better understand gas-and particle-phase interactions in the atmosphere. The Environmental Protection Agency’s (EPA) Community Multiscale Air Quality (CMAQ) model couples meteorological, emission, and chemical transport predictions to simulate air pollution from local to hemispheric scales. CMAQ provides scientists and regulatory agencies with important assistance in air quality management, policy enactment, atmospheric research, and creating public health advisories. Recently, a new update to CMAQ (v5.4) was released, utilizing new chemistry mechanisms and incorporating a new atmospheric chemistry model. This study evaluates the performance of the latest model update by analyzing multiple time series of vertical distributions of formaldehyde (CH2O) and methane (CH4) in the Los Angeles Basin and Central Valley regions of California. It compares data from aloft measurements taken during NASA SARP 2017 flights with model predictions to evaluate accuracy. Our study analyzes CMAQ’s capabilities in capturing the vertical dispersion of CH2O and CH4 in different regions, offering insights into the effectiveness of CMAQ for air quality management and the analysis of trace and greenhouse gas dynamics. Using NASA airborne data, this research utilizes a diversified data set to validate the model, providing a more comprehensive evaluation of its capabilities, and thus providing valuable insight into future developments of CMAQ.
Alison Thieberg
Estimating Aerosol Optical Properties Using Mie Theory and Analyzing Their Impact on Radiative Forcing in California
Alison Thieberg, Emory University
Anthropogenic aerosols, unlike greenhouse gasses, provide a net cooling effect to the Earth’s surface. Particles suspended in the atmosphere have the ability to scatter incoming solar radiation, preventing that radiation from heating up the surface. These aerosols like black carbon, ammonium nitrate, ammonium sulfate, and organics are byproducts of both natural and anthropogenic activities. Measuring radiative forcing as a result of these aerosols over time can provide insight on how anthropogenic industries are altering our Earth’s temperature. This study analyzes the changes in radiative forcing from aerosols in central and southern California using data collected from NASA SARP flights from 2016-2024. Aerosol size, composition, and single scattering albedo were used to estimate the aerosol characteristics and to calculate the aerosols’ radiative forcing efficiency. Our results show that aerosols are found to have less of a cooling effect over time when looking at the change in radiative forcing in California from 2016 to 2024. When narrowing in on specific geographic regions, we observe the same trends in the Central Valley with the area becoming warmer as a result of aerosols. However, more southern regions like Los Angeles and the Inland Empire have become cooler from aerosols during this time period. The overall decrease in the cooling effect of California’s aerosols could indicate that the average size of particulates is changing or that the aerosol composition could be shifting to a greater concentration of absorbing aerosols rather than scattering aerosols. This study shows how aerosols influence radiative forcing and their subsequent impacts across regions in California from multiple years.
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Last Updated Sep 25, 2024 Related Terms
General View the full article
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By Space Force
As Delivered by Chief of Space Operations U.S. Space Force Gen. Chance Saltzman on September 17, 2024
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