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NASA Employees Speak Against Cuts in Open Letter

EOS - Tue, 07/22/2025 - 17:49
body {background-color: #D2D1D5;} Research & Developments is a blog for brief updates that provide context for the flurry of news regarding law and policy changes that impact science and scientists today.

Nearly 300 current and former NASA employees have signed an open letter expressing concern that budget cuts to the agency will jeopardize safety, basic research, national security, and the nation’s economic health. 

The 21 July letter, titled “The Voyager Declaration,” in honor of the Voyager space probes, was addressed to Interim NASA Administrator Sean Duffy, who joined the agency on 9 July. 

“We are compelled to speak up when our leadership prioritizes political momentum over human safety, scientific advancement, and efficient use of public resources,” the letter states. “The consequences for the agency and the country alike are dire.”

The agency faces pressure to reduce its staff and a budget request proposing funding at levels described as an “extinction-level event for NASA science” by Casey Dreier, chief of space policy for the Planetary Society. 

 
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In the letter, signatories asked Duffy to protect NASA from proposed budget and staffing cuts and dissented to several planned or already-enacted changes including spacecraft decommissioning; abandonment of international space mission partnerships; and termination of diversity, equity, inclusion, and accessibility programming.

The letter’s authors also pointed out a “culture of organizational silence” promoted at the agency that, combined with suggested changes to NASA’s Technical Authority—a system of safety oversight—represents a “dangerous turn away from the lessons learned following the Columbia disaster.” The letter was dedicated to astronauts who lost their lives in spaceflight incidents and was signed by at least 4 astronauts.

“We’re scared of retaliation,” Monica Gorman, an operations research analyst at NASA’s Goddard Space Flight Center and a signatory of the letter, told the New York Times. She said staff “go to the bathroom to talk to each other, and look under the stalls to make sure that no one else is there before we talk.”

Staff at the National Institutes of Health and the EPA signed similar letters to their administrators in June. Some of the signatories of the EPA letter have since been placed on leave. Stand Up for Science, a nonprofit science advocacy organization, helped coordinate all three letters. 

—Grace van Deelen (@gvd.bsky.social), Staff Writer

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Abrupt climate shifts likely as global temperatures keep rising

Phys.org: Earth science - Tue, 07/22/2025 - 17:10
As temperatures, biodiversity losses, and sea levels rise globally, scientists are concerned about the likelihood of abrupt climatic shifts occurring, particularly within sensitive subsystems of the climate system such as the Amazon rainforest, Antarctic sea ice, and the Tibetan Plateau. Abrupt shifts can manifest as, for example, large and sudden changes in the rate of precipitation in a monsoon system, ice melt in Antarctica, or permafrost thaw in the Northern Hemisphere.

New Insights into How Rocks Behave Under Stress

EOS - Tue, 07/22/2025 - 14:24
Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Solid Earth

Understanding how rocks break in the brittle upper crust is critical for predicting earthquakes, managing reservoirs, and modeling subsurface mechanics. In JGR: Solid Earth, two new studies by Jacob et al. [2025] and Hurley et al. [2025] use cutting-edge synchrotron-based X-ray diffraction techniques to reveal how stress evolves at the grain scale inside sandstone samples under load.

In both studies, researchers applied increasing axial compression to small cores of sandstone rocks, while scanning them with high-energy X-rays at a synchrotron radiation facility. Jacob et al. [2025] employed a technique called scanning three-dimensional X-ray diffraction to obtain high-resolution maps of intra-granular stress in the sandstone. By combining stress mapping with stepwise compression, the team observed increasing stress heterogeneity accompanied by dynamic reorientation of local stresses. High-stress clusters emerged and formed spatially persistent structures. These patterns were found to correlate with zones of higher grain rotation and strain, forming potential precursors to failure.

Hurley et al. [2025] combined X-ray tomography with three-dimensional X-ray diffraction and near-field high-energy diffraction microscopy to image stress and texture evolution in 3D. The researchers observed that larger grains showed more internal misorientation, possibly due to the presence of surface cements. By combining stress mapping with stepwise compression, the team showed that grain stresses demonstrated compressive stress alignment parallel to the loading direction and tensile stresses alignment orthogonal to the loading direction. This evolution was consistent with porosity evolution revealed by X-ray tomography, which showed pores closing parallel to the loading direction and opening normal to the loading direction.

Together, these studies reveal that rocks under stress behave more like collections of interacting grains than uniform solid blocks, showing similarities with inter-particle force transmission in granular materials. They also underscore the power of modern synchrotron tools in capturing these processes while performing rock deformation experiments, providing deeper insights into how brittle failure initiates in the Earth’s crust.

Citations:

Jacob, J.-B., Cordonnier, B., Zhu, W., Vishnu, A. R., Wright, J., & Renard, F. (2025). Tracking intragranular stress evolution in deforming sandstone using X-rays. Journal of Geophysical Research: Solid Earth, 130, e2025JB031614. https://doi.org/10.1029/2025JB031614

Hurley, R. C., Tian, Y., Thakur, M. M., Park, J.-S., Kenesei, P., Sharma, H., et al. (2025). Crystallographic texture, structure, and stress transmission in Nugget sandstone examined with X-ray tomography and diffraction microscopy. Journal of Geophysical Research: Solid Earth, 130, e2025JB031690. https://doi.org/10.1029/2025JB031690

—Yves Bernabé, Editor, JGR: Solid Earth

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Researchers use AI to identify landslides and target disaster response

Phys.org: Earth science - Tue, 07/22/2025 - 14:20
Researchers from the University of Cambridge are using AI to speed up landslide detection following major earthquakes and extreme rainfall events—buying valuable time to coordinate relief efforts and reduce humanitarian impacts.

Scientists use X-rays to remotely measure magnetic reconnection in near-Earth space

Phys.org: Earth science - Tue, 07/22/2025 - 13:50
The magnetosphere, formed by Earth's magnetic field, acts as a protective shield that deflects solar wind—the flow of charged particles constantly streaming from the sun toward our planet. This magnetic barrier protects our atmosphere and the technology we increasingly depend on in near-Earth space, such as communication satellites.

Groundwater Pollution in Karst Regions: Toward Better Models

EOS - Tue, 07/22/2025 - 13:12
Editors’ Vox is a blog from AGU’s Publications Department.

Karst groundwaters are vital resources, providing drinking water to nearly 10% of the world’s population. However, human activities and global change have deteriorated the karst water quality and dependent ecosystems.

A new article in Reviews of Geophysics explores contaminant transport in karst groundwaters and recent efforts to model it. Here, we asked the authors to give an overview of karst aquifers, how scientists model contaminant transport, and future research directions.

What are karst aquifers and where do they form?

Karst aquifers are underground water reservoirs that develop in soluble rocks like limestone or dolomite. Over thousands of years, these rocks dissolve to form complex underground networks of channels, caves, and fractures (Figure 1). These unique systems are found all over the world—from Florida to the Dinaric Alps—and they supply drinking water for nearly one in ten people globally while supporting ecosystem functioning.

Figure 1: Conceptual representations of transport processes in karst aquifer at differing spatial scales. a) 3D block diagram of a karst aquifer scale, b) aquifer scale, c) borehole scale, d) single-fracture scale, e) pore-scale level (described at the Representative Elementary Volume, REV). Here, contaminant degradation is described by the chemical transformation influenced by physical, chemical, and (biogeo)chemical processes. The figure only describes anthropogenic contamination by indicating diffuse (areal) and point sources because both are key contamination sources in karst aquifers. Credit: Çallı et al. [2025], Figure 1

Why are karst aquifers important to understand?

Karst aquifers are both vital and vulnerable. They respond quickly to environmental changes, and pollutants can spread rapidly through their distinctive underground networks. Because water moves so fast and through unpredictable pathways, it’s hard to know how long contaminants will persist or where they’ll go. Understanding them is key to ensuring safe drinking water and protecting the ecosystems that depend on them.

What are the main sources of contamination in karst aquifers?

Contaminants come from both natural and human-made sources. Industrial chemicals, agricultural runoff, sewage, and land use changes are common threats. Even natural elements like arsenic or uranium can pose risks if they dissolve into groundwater. Due to the thin soils and fast-moving water in karst aquifers, there’s little time or space for these pollutants to be filtered or degraded before they spread (Figure 1).

How do scientists monitor for contamination in karst aquifers?

Scientists use tracer tests—adding a harmless dye or chemical to water and tracking where it goes—to map water flow. They also analyze natural “tracers” like isotopes or chemical signals already in the water. These techniques help us understand how fast water travels, how long it stays underground, and how different sources mix (Figure 2). This information is essential for predicting contamination risks, and support efforts to protect karst water resources.

Figure 2: Monitoring spatiotemporal distributions of contaminant plumes across the karst systems. Here, the acronyms Adv, Dis, and Diff refer to advection (or advective flow), dispersion, and diffusion processes, respectively. Sp (sorption) and Rc (chemical reaction) indicate the impact of retardation and reactive processes on the movement of solute plume. In the figure, C0 and C refer to the initial solute concentration and the concentration of solute at a given time, respectively. Here, ti indicates the first detection time of solute of interest (e.g., at the observation well) and tobs refers to the observed concentrations at the time of interest. In the figure, the two-way red arrows indicate the solute/mass exchange between the conduit and the matrix. Credit: Çallı et al. [2025], Figure 3

What kinds of models are being developed to track the movement of contaminants within karsts?

Researchers are developing computer models that simulate how water and contaminants move through the complex karst network. These models range from simplified, large-scale representations to detailed simulations of karst flow through conduits and fractures (Figure 3). They help us explore different scenarios—like how a pollutant might spread after a flood or how land use changes affect water quality. Therefore, they are essential for effectively managing karst water quality and planning pollution prevention strategies.

Figure 3: Generic classification of karst simulation models based on the model parametrization considering process complexity and data requirement. a) Conceptualization of the karst aquifer physical boundaries depicted by the grey-shaded area with a blue-indicated karst conduit and conduit network (the blank circles also describe the swallets/sinkholes along the conduit network), b) Spatially lumped karst simulation models depicted based on the solute concentration distribution over different karst compartments including epikarst, conduit, and matrix, c) Spatially distributed karst simulation models described considering the spatial distribution of the solute concentration. The classification is adapted from Hartmann et al. [2014]. Herein, a tracer test is described only to demonstrate the spatial distributions of contamination plume across two main karst simulation approaches. Credit: Çallı et al. [2025], Figure 9

What are some of the challenges of karst transport modeling?

The biggest challenge is heterogeneity—karst systems are incredibly variable at all scales. We often lack detailed data on the shape of the underground conduits, flow speeds, or chemical conditions. This makes it difficult to build reliable models. Even small changes in how water moves can greatly affect contaminant behavior, so improving model accuracy is a major research focus.

What additional research, data, or modeling efforts are needed to overcome these challenges?

We need better field data—from tracer tests, groundwater monitoring, and mapping—to calibrate and validate models. Advances in remote sensing and machine learning also offer new tools. Future research should focus on integrating hydrological, chemical, and biological processes and on translating model results into actionable decisions. Collaboration across disciplines is key to (better) understanding, managing, and protecting karst water resources in a changing world.

—Kübra Özdemir Çallı (kuebra.oezdemir_calli@tu-dresden.de, 0000-0003-0649-6687), Institute of Groundwater Management, TU Dresden, Germany; and Andreas Hartmann (andreas.hartmann@tu-dresden.de, 0000-0003-0407-742X), Institute of Groundwater Management, TU Dresden, Germany

Citation: Çallı, K. Ö., and A. Hartmann (2025), Groundwater pollution in karst regions: toward better models, Eos, 106, https://doi.org/10.1029/2025EO255022. Published on 22 July 2025. This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s). Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Abrupt Climate Shifts Likely as Global Temperatures Keep Rising

EOS - Tue, 07/22/2025 - 12:54
Source: AGU Advances

As temperatures, biodiversity losses, and sea levels rise globally, scientists are concerned about the likelihood of abrupt climatic shifts occurring, particularly within sensitive subsystems of the climate system such as the Amazon rainforest, Antarctic sea ice, and the Tibetan Plateau. Abrupt shifts can manifest as, for example, large and sudden changes in the rate of precipitation in a monsoon system, ice melt in Antarctica, or permafrost thaw in the Northern Hemisphere.

Terpstra et al. sought to identify abrupt shifts that might occur in the future, focusing on climate subsystems discussed in the 2023 Global Tipping Points Report. The team examined outputs from 57 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6). All the models simulated a climate change scenario over 150 years, with carbon dioxide concentration increasing by 1% annually until it reached 4 times preindustrial levels.

They then applied a method called Canny edge detection, which was originally created to identify edges in computer images, to the modeled climate data. In this case, they used it to detect edges, or points in time and space, where abrupt changes occurred within a decade across 82 variables, such as sea surface salinity, soil moisture content, and carbon mass in vegetation and soil. Prior research used a similar method to scan for edges in climate data, but not at the subsystem scale.

Although the researchers observed large variations among the model scenarios, 48 of the 57 showed an abrupt shift in at least one subsystem over the modeled period. Monsoon systems were outliers: Only one model indicated an abrupt shift in the Indian summer monsoon, and none indicated abrupt shifts in the South American and West African monsoons.

They also found that the more global warming a model simulated, the higher the likelihood was of abrupt shifts happening. At 1.5°C above average preindustrial temperatures, the target limit set by the Paris climate agreement, the researchers found that 6 out of 10 studied climate subsystems showed large-scale abrupt shifts across multiple models. (AGU Advances, https://doi.org/10.1029/2025AV001698, 2025)

—Sarah Derouin (@sarahderouin.com), Science Writer

Citation: Derouin, S. (2025), Abrupt climate shifts likely as global temperatures keep rising, Eos, 106, https://doi.org/10.1029/2025EO250270. Published on 22 July 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

New model indicates 320 million trees are killed by lightning each year—considerable biomass loss

Phys.org: Earth science - Tue, 07/22/2025 - 11:30
Lightning has a greater impact on forests than previously thought. Researchers at the Technical University of Munich (TUM) have developed new model calculations that, for the first time, estimate the global influence of lightning on forest ecosystems.

Overlooked climate-change danger: Wildfire smoke

Phys.org: Earth science - Tue, 07/22/2025 - 11:30
Loretta Mickley first started thinking about smoke in the summer of 2002.

Naval Postgraduate School launches sustainable buoy to advance research

Phys.org: Earth science - Tue, 07/22/2025 - 11:10
Located about 3 miles offshore and 5 miles north of the Naval Postgraduate School is a first-of-its-kind ocean-sensing buoy. With 5G technologies and solar panels built in, the buoy has the capabilities to collect oceanographic and meteorological data 24 hours a day, seven days a week for the next three years.

Seismic imaging of pure quasi-P-wave in the VTI media by using the optical flow to calculate phase-velocity direction

Geophysical Journal International - Tue, 07/22/2025 - 00:00
SummaryIncorporating anisotropy in seismic imaging is important to produce correct locations and amplitudes of subsurface reflectors. The pure quasi-P-wave equation has a good accuracy to describe wave propagation in the anisotropic media, but it requires complicated computation strategies. To mitigate this issue, we present a novel pure quasi-P-wave equation in the vertical transverse isotropic (VTI) media with a nonlinear scalar operator, which is determined by the anisotropic parameters and the phase-velocity vector. Inaccurately calculating the directions of wave propagation results in incorrect phase-velocity vector and accumulated simulation error. Here, we utilize the optical flow to accurately calculate the direction of wave propagation while maintaining computational efficiency. Then, we optimize the wavefield simulation workflow and accelerate the calculation of optical flow. Numerical experiments show that the proposed wavefield simulation method can accurately describe wave propagation in the VTI media with good computational efficiency. Finally, we apply the proposed method to reverse-time migration to correct the anisotropic effects in seismic imaging. Numerical tests for benchmark models and a land survey demonstrate the feasibility and adaptability of the proposed method.

Seismic study reveals hidden megathrust earthquake risk off British Columbia

Phys.org: Earth science - Mon, 07/21/2025 - 14:30
A new study published in Science Advances has revealed the first detailed images of a newly developing subduction zone off the coast of British Columbia's Haida Gwaii archipelago.

New map reveals 332 Antarctic submarine canyons, five times more than before

Phys.org: Earth science - Mon, 07/21/2025 - 14:20
Submarine canyons are among the most spectacular and fascinating geological formations to be found on our ocean floors, but at an international level, scientists have yet to uncover many of their secrets, especially those located in remote regions of Earth like the North and South Poles.

Ocean nutrient ratios shift, challenging the long-standing Redfield Ratio model

Phys.org: Earth science - Mon, 07/21/2025 - 13:50
A new study published in Nature Geoscience has revealed that the global ocean's chemical makeup is undergoing a transformation, with key nutrient ratios critical to marine life shifting away from the long-accepted Redfield Ratio over the past decades.

Curved fault slip captured on CCTV during Myanmar earthquake

Phys.org: Earth science - Mon, 07/21/2025 - 13:40
Dramatic CCTV video of fault slip during a large earthquake in Myanmar thrilled both scientists and casual observers when it was posted to YouTube. But it was on his fifth or sixth viewing, said geophysicist Jesse Kearse, that he spotted something even more exciting.

Living with climate change: How to adapt to rising sea levels and changing rainfall patterns at the North Sea coast

Phys.org: Earth science - Mon, 07/21/2025 - 13:13
The trek across the North Sea island of Norderney—a barrier island in the German North Sea—is around five kilometers long. Designed by Lena Thissen, a researcher from the University of Oldenburg, Germany, together with a social scientist from the University of Hamburg, the "Freshwater Lens Walk" is all about a hidden treasure: the island's freshwater supply.

New Research Shows More Extreme Global Warming Impacts Looming for the Northeast

EOS - Mon, 07/21/2025 - 12:00

This article originally appeared on Inside Climate News, a nonprofit, non-partisan news organization that covers climate, energy, and the environment. Sign up for its newsletter here.

A pair of new climate studies suggest an intensification of strong storms called nor’easters and other disruptive extremes affecting the East Coast of North America on an overheated planet.

Nor’easters generally form within about 100 miles of the East Coast between North Carolina and Massachusetts, often when cooler air from Canada meets warm, moist air over Gulf Stream waters. Those contrasting air masses can start to spin with a nudge from the jet stream, fueling storms that can produce damaging winds, coastal flooding and intense, disruptive snowfall in the winter.

The strongest nor’easters are already significantly windier and rainer than they were in the middle of the 20th century, said University of Pennsylvania climate scientist Michael Mann, a coauthor of a study published on 14 July in the Proceedings of the National Academy of Sciences.

A 2022 study showed a similar trend of intensification for storms forming over the Atlantic and hitting Europe, and that the track of those storms is moving northward, potentially putting unsuspecting areas more at risk.

Mann said the increases in the intensity and precipitation rates of the strongest nor’easters have likely been fueled by increases in ocean temperatures and the increased moisture capacity of a warming atmosphere.

“There are two reasons to look at the most intense nor’easters,” Mann said via email. “First, from an impact standpoint, they do the most damage, including coastal erosion, destruction and paralyzing snowfalls. The 1962 Ash Wednesday storm, with 84 mile per hour gusts, is a great example. In today’s dollars, it did $21 billion worth of damage.”

And just last February, a classic nor’easter described at the time as a “bomb cyclone” dropped several feet of snow over parts of Virginia and North Carolina and caused damaging flooding along parts of the Massachusetts coast, Eastern Long Island, and the Jersey Shore.

Mann said the increases in the intensity and precipitation rates of the strongest nor’easters have likely been fueled by increases in ocean temperatures and the increased moisture capacity of a warming atmosphere.

The researchers tracked 900 nor’easters back to 1940 in combination with a careful reanalysis of historical climate conditions surrounding the storms, including notable events like the Perfect Storm in 1991, Storm of the Century in 1993, and Snowmaggedon in 2010.

In the very strongest storms, the wind speeds have increased about 5.4%, from 69 to 71 mph, “but since destructive potential goes as the wind speed cubed, that’s a roughly 17% increase in destructive potential,” Mann said.

Overall, he added, a lot of research suggests that extra warming in the Arctic, which reduces the temperature contrast between high latitudes and midlatitudes, will lead to less storminess overall, but the destructive potential of intensifying nor’easters warrants attention.

Compared to other types of storms, nor’easters feed more off the heat of the ocean, which remains considerable in winter, “So those storms that can make it past the obstacles to development have the potential to grow stronger than they otherwise would have,” he said. “While we don’t see any evidence of increased intensity for the ‘average’ nor’easter, the strongest ones are clearly getting stronger.”

“My interest in these storms, and how they’re being impacted by climate change has been inspired by two personal experiences,” he said, first noting the March 1993 “storm of the century,” which caused 270 deaths and $12.2 billion worth of damage across 26 states, according to the National Ocean and Atmospheric Administration.

Mann said the storm disrupted a spring break road trip in Florida, where the temperature in St. Augustine dropped from the 70s to 40s in a few hours.

“We drove past Okefenokee Swamp later that day and it was snowing,” Mann said. “Then we stopped off in Southern Georgia for the night and temperatures dropped to the mid 20s. We froze. I will never forget that.”

“The strongest nor’easters can have impacts comparable to category 1 and 2 hurricanes, with effects encompassing a larger area.”

He said he remembers another infamous nor’easter, Snowmaggedon, from February 2010 because a U.S. senator who rejects science that proves human-caused warming used the occasion to build what he called an igloo in an attempt to cast doubt on climate science. At the same time, Mann said he ended up stuck in a hotel room for three days with several feet of snow blocking most roads in Pennsylvania.

As such storms grow stronger in a warming world, said Anthony Broccoli, an atmospheric scientist at Rutgers University who was not involved in the new study but who also researches nor’easters, “it will be important to remember that the strongest nor’easters can have impacts comparable to category 1 and 2 hurricanes, with effects encompassing a larger area.”

With sea level rise accelerating along the East Coast, Broccoli added that nor’easters “will lead to greater coastal flooding even without any changes in storm intensity.”

The increased thermal energy from warming oceans is likely driving the trend toward stronger nor’easters, and there could be other large-scale changes to ocean currents and winds that could shift the tracks of nor’easters, potentially raising unexpected risks in new areas, he said.

The new research doesn’t mean that temperatures are getting colder, but that the frigid air that still does form over the Arctic in winter will still make its way south, showing up perhaps more frequently in unexpected regions, or with increased unusual seasonal extremes that can damage crops.

The Arctic Connection

Large-scale changes affecting nor’easters and cold weather extremes in the United States likely include accelerated warming of the Arctic region, climatologist Judah Cohen said in an email interview. Cohen, a visiting scientist at MIT and director of seasonal research with Atmospheric and Environmental Research, published an 11 July study in Science Advances that bolsters evidence for a climate connection.

Cohen said that, as far as he’s concerned, the new paper is “preaching to the choir,” because its conclusions are consistent with his own research showing that “Arctic change can lead to episodic increases in severe winter weather in the U.S. east of the Rockies including extreme cold and disruptive snowfalls.”

The temperature contrast between the Arctic and the midlatitudes is one of the main forces that creates key winds at different altitudes, like the jet stream and polar vortex, and moves weather systems around the Northern Hemisphere.

Cohen’s work over recent years suggests that accelerated warming of the Arctic “stretches” the polar vortex—like elongating a round rubber band—into positions that let cold polar air spill southward more frequently.

He noted that two of the most recent nor’easters specifically named in the new paper by Mann and his coauthors, in March 1993 and January 2018, occurred during stretched polar vortex events. The new paper, he said, “provides a medley of possible causes but doesn’t settle on any one cause.”

His own recent paper, he said, shows “for the first time that stretched polar vortex events are overwhelmingly associated with extreme cold and heavy snowfall in the Eastern U.S.,” compared to other polar vortex configurations.

Often the polar vortex flows in a tight coil around the North Pole, containing the Arctic air, but Cohen’s study, and other research, suggest a trend to more frequent stretched polar vortexes and the associated cold-air outbreaks and storm impacts. Taken altogether, he said the new research helps explain regional “winter cooling trends and an increased number of heavy snowfalls in the Eastern U.S. over the past two and a half decades.”

—Bob Berwyn (@bberwyn), Inside Climate News

Nonlinear kinetic simulations of Jeans instability in a magnetized dusty plasma

Physical Review E (Plasma physics) - Mon, 07/21/2025 - 10:00

Author(s): Masaru Nakanotani, Luis Lazcano Torres, Gary P. Zank, and Edward Thomas, Jr.

The Jeans instability in a magnetized dusty plasma is considered a fundamental process in space, where magnetic fields are common. We investigate the Jeans instability in a magnetized dusty plasma using 1D and 2D particle-in-cell simulations, in which dust grains are treated as particles and the Poi…


[Phys. Rev. E 112, 015208] Published Mon Jul 21, 2025

Spontaneous Potential Surveys in Surface Fresh Waters for Engineering and Environmental Applications

Geophysical Journal International - Mon, 07/21/2025 - 00:00
AbstractGeophysicists using the spontaneous potential method measure differences in electrical potential without providing an active source of current. Most spontaneous potential surveys have been carried out on land or in marine environments. In the present paper, I evaluate the use of the spontaneous potential method in surface fresh water for small-scale environmental and engineering applications. In one survey reported here, the electrical potential between an electrode at the river edge and one suspended from a bridge was used to measure a high resolution profile across a river. In another, electrical potentials were measured between sets of electrodes mounted on a canoe. In both surveys, significant and consistent anomalies were detected particularly near bridge structures, and simple modeling in terms of point sources and line sources was undertaken to better characterize the causes of the anomalies. The possibility of an induction-induced voltage difference across the river caused by Earth’s magnetic field and flow in the river was also investigated. The absence of this potential is attributed to significant electrical conduction through the riverbed. The present work demonstrates the utility of spontaneous potential as a technique for detecting and characterizing anomalies of environmental and engineering interest in fresh water environments.

Modeling P wave reflections on MTZ discontinuities from distant oceanic sources

Geophysical Journal International - Mon, 07/21/2025 - 00:00
AbstractWe investigate the modeling of P-wave reflections on the mantle transition zone (MTZ) discontinuities (Pv410p* and Pv660p*) using ambient seismic noise generated by distant oceanic sources. Using ray theory and waveform simulations, we assess biases in arrival times and amplitude ratios when interpreting noise correlations as Green‘s functions. Our results show that source distribution and the b-caustic effect strongly influence signal recovery. Simulations based on realistic oceanic models (WAVEWATCH III) demonstrate that appropriate source conditions significantly reduce biases. This approach enables reliable imaging of the MTZ, particularly in regions like the greater Alpine area with favorable microseismic source distribution.

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