When the sky takes a midday dip: global patterns in ionospheric bite-outs

Aerospace Information Research Institute, Chinese Academy of Sciences

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Average noontime bite-outs intensities (Ibt) in 2014 and 2020. Using Ibt as the intensity metric, (a) and (b) represent the average noontime bite-outs intensities for 2014 and 2020, respectively, in units of TECu. The color scale indicates Ibt of the noontime bite-outs, with warmer colors representing higher value. The region with a value of 0 indicate that no noontime bite-out pattern occurred in those areas during that month.

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Credit: Satellite Navigation

Around midday, Earth’s ionosphere sometimes experiences sharp, short-lived dips in its electron density—an unusual phenomenon known as a noontime bite-out. A new study takes a global view of these midday disruptions, using finely detailed ionospheric maps to compare their behavior in years of high and low solar activity. The research reveals that noontime bite-outs are more widespread and frequent during solar minimum, especially in winter and at higher latitudes. With detailed tracking of timing, intensity, and duration, the study provides a clearer picture of this elusive phenomenon and offers fresh insights into the daily rhythms of space weather.

The ionosphere is a critical layer of Earth's upper atmosphere that affects radio communications and satellite navigation by reflecting and refracting electromagnetic signals. Among its many behaviors, one stands out for its peculiarity: a sudden midday dip in electron content. These noontime bite-outs, first observed decades ago, can disrupt signals and complicate space weather forecasting. While regional studies have documented the occurrence of bite-outs, their global distribution and causes remain unclear. Due to these uncertainties, there is a growing need to explore their full spatiotemporal characteristics using global, high-resolution datasets.

A research team from Hohai University and Beihang University has published (DOI: 10.1186/s43020-025-00164-x) the most comprehensive analysis to date of ionospheric noontime bite-outs, using five-minute resolution global ionospheric map (GIM) data. The study, released in Satellite Navigation in May 2025, compares bite-out events from 2014 and 2020—years representing solar maximum and minimum, respectively. By scanning latitudes from pole to pole, the team was able to examine how these electron density dips vary with solar activity, season, and geographic location.

The study reveals that noontime bite-outs are significantly more frequent during periods of low solar activity. In 2020, their occurrence extended to wider regions, especially in mid- and high-latitudes, compared to 2014. The team also discovered that winter months consistently show the highest occurrence rates, likely due to lower ionospheric electron content and weaker solar radiation. Using two different intensity metrics—a relative ratio and an absolute value—they showed how bite-outs manifest differently across regions. Most events peaked around 13:00 local time and lasted between 2.5 and 6 hours, with longer durations typically found in summer and during solar maximum years. The underlying causes vary by latitude: near the equator, plasma dynamics such as the fountain effect dominate, while in higher latitudes, poleward winds and neutral atmospheric processes play a larger role. This broad comparison establishes a new benchmark for understanding ionospheric dynamics on a planetary scale.

“This work marks a major advance in our ability to monitor and understand daily ionospheric fluctuations,” said Dr. Cheng Wang, senior author of the study. “For the first time, we have a global, time-resolved picture of how noontime bite-outs behave under different solar and seasonal conditions. These findings will be instrumental in future efforts to model space weather and mitigate its effects on navigation and communication systems.”

By clarifying when and where noontime bite-outs are likely to occur, the study paves the way for more resilient satellite-based systems. Communications and GNSS signals are particularly vulnerable to sudden ionospheric changes, and predictive models could benefit from this new understanding of midday dips. Moreover, the intensity metrics and global mapping approaches developed here offer tools for future studies on ionospheric variability. As solar activity continues to fluctuate, combining physical models with real-time data could unlock better forecasting tools—helping both scientists and engineers navigate the invisible landscape above.

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References

DOI

10.1186/s43020-025-00164-x

Original Source URL

https://doi.org/10.1186/s43020-025-00164-x

Funding information

This study has been funded by the National Key R&D Program of China (No. 2022YFB3904402) and the National Natural Science Foundation of China (No. 42474037).

About Satellite Navigation

Satellite Navigation (E-ISSN: 2662-1363; ISSN: 2662-9291) is the official journal of Aerospace Information Research Institute, Chinese Academy of Sciences. The journal aims to report innovative ideas, new results or progress on the theoretical techniques and applications of satellite navigation. The journal welcomes original articles, reviews and commentaries.

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Journal

Satellite Navigation

DOI

10.1186/s43020-025-00164-x 

Subject of Research

Not applicable

Article Title

Analysis of the global spatiotemporal characteristics of ionospheric noontime bite-outs

 

Scientists uncover a fungal protein critical to causing fusarium head blight in cereal crops

Researchers have discovered a secreted fungal protease FgTPP1 that suppresses plant immune defenses and could be the key to engineering Fusarium head blight-resistant cereal grains

American Phytopathological Society

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The PH-1-ΔFgtpp1-1 mutant did not show an observable virulence defect when wheat spikes were inoculated using the top-inoculation method. Yellow arrows indicate inoculation points. Wheat spikes infected with either the ΔFgtpp1-1 mutant (PH-1-ΔFgtpp1-1) or wild-type F. graminearum PH-1 strain showed similar disease symptoms (left). The number of diseased spikelets throughout the time courses for the ΔFgtpp1-1 mutant and wild-type F. graminearum PH-1 were similar (middle), and the area under the disease progress curve (AUDPC) values calculated for the mutant and wild type did not reveal significant differences (right). Violin plots show distribution of the AUDPC values (black dots), average AUDPC values, and confidence intervals (rectangles) for each fungal strain. The statistical analysis (t test) included pooled data from three independent replicates. Each replicate consisted of 12 plants, where 6 plants (one spike per plant) were inoculated with either ΔFgtpp1-1 mutant or wild-type F. graminearum PH-1 strains (the total number of plants inoculated was 17 and 18 for the ΔFgtpp1-1 mutant and wild-type F. graminearum PH-1 strain, respectively).

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Credit: Courtesy of Matthew Helm.

A breakthrough study published in Molecular Plant-Microbe Interactions® (MPMI) reveals how the destructive fungal pathogen Fusarium graminearum uses a specialized protein to weaken plant immune defenses and cause Fusarium head blight (FHB), a devastating disease that severely damages wheat and barley crops worldwide. These new insights into how F. graminearum attacks crops could lead to the development of genetically engineered disease-resistant grains.

This collaborative research team, led by Matthew Helm of the U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS), West Lafayette, Indiana, Roger Innes at Indiana University Bloomington, and Kim Hammond-Kosack at Rothamsted Research in the United Kingdom identified and functionally characterized a fungal protein called TPP1. This effector protease is secreted by F. graminearum during infection and plays a central role in helping the fungus overcome plant defenses by targeting the chloroplast—an essential part of the plant cell responsible not only for energy production but also for immune signaling.

“What excites us most is that this effector protease not only promotes disease but also targets a specialized plant cell structure known as the chloroplast, which is an unexpected and strategic location for disarming the plant’s immune system,” Helm said. He added, “This study could be transformational for developing disease-resistant crops.”

FHB continues to threaten global food security, causing significant yield losses and contaminating grain with mycotoxins that are harmful to humans and livestock. In this study, researchers showed that when the gene for TPP1 was knocked out, the fungus became significantly less virulent, confirming that this protein is essential for infection. The finding sheds light on a largely unexplored mechanism in fungal pathogenesis.

This is the first report to identify an effector protease from F. graminearum that targets the chloroplast and directly contributes to disease development by suppressing plant immune responses. “The discovery of TPP1’s role marks a significant advancement in our understanding of fungal pathogenesis. It also opens up exciting possibilities for using ‘decoy’ engineering strategies to develop wheat and barley varieties with built-in resistance,” the research team noted.

“In addition, TPP1 appears to be highly conserved across a broad group of fungal pathogens, making it potentially a prime target to deliver plant disease resistance against other problematic fungal species” said Hammond-Kosack.

With implications for both the plant-microbe and broader host-microbe research fields, this foundational work brings researchers one step closer to long-term goals of reducing crop loss and ensuring food security. It lays the groundwork for bioengineering more resilient wheat and barley varieties, which is an urgent need in the face of a changing climate and rising global food demand. “Our ultimate goal,” the authors said, “is to protect global food supplies by reducing crop losses from Fusarium head blight. This study is an important step toward that goal.”

For additional details, read “The Fusarium graminearum Effector Protease FgTPP1 suppresses Immune Responses and Facilitates Fusarium Head Blight Disease,” published in MPMI.

Follow the authors on X at:

Namrata Jaiswal: @Namrata_biolab

Martin Darino: @DarinoMartin

Reynaldi Darma: @rey_darm_

Matthew Helm: @mattdhelm19

Follow the authors on LinkedIn at:

Namrata Jaiswal: www.linkedin.com/in/namrata-jaiswal-33363291/

Martin Darino: https://www.linkedin.com/in/martin-darino-06a677197/

Reynaldi Darma: https://www.linkedin.com/in/reynaldi-darma-2124bb98/

Matthew Helm: https://www.linkedin.com/in/matthew-helm-ph-d-0b322838/

Roger Innes: https://www.linkedin.com/in/roger-innes-2481061b/

About Molecular Plant-Microbe Interactions® (MPMI) 

Molecular Plant-Microbe Interactions® (MPMI) is a gold open access journal that publishes fundamental and advanced applied research on the genetics, genomics, molecular biology, biochemistry, and biophysics of pathological, symbiotic, and associative interactions of microbes, insects, nematodes, or parasitic plants with plants. MPMI is published in collaboration by The American Phytopathological Society and the International Society for Molecular Plant-Microbe Interactions.
 

Follow us on X @MPMIjournal, Bluesky @mpmijournal.bsky.social, and visit https://apsjournals.apsnet.org/journal/mpmi to learn more.

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Journal

Molecular Plant-Microbe Interactions

DOI

10.1094/MPMI-08-24-0103-FI 

Article Title

The Fusarium graminearum Effector Protease FgTPP1 Suppresses Immune Responses and Facilitates Fusarium Head Blight Disease

UMass Amherst research discovery could lead to a natural tick repellent

Secret ingredient: Donkey skin secretion

University of Massachusetts Amherst

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Microbiologist Stephen Rich is executive director of the New England Center of Excellence in Vector-borne Diseases, based at UMass Amherst. 

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Credit: UMass Amherst

University of Massachusetts Amherst researchers have made a promising discovery that could lead to the development of a natural and effective tick repellent. They have shown that a naturally occurring compound secreted by the skin of donkeys effectively repels adult Ixodes scapularis ticks – the most frequent human-biting tick in the U.S. Commonly known as the deer tick, this species of arthropods is responsible for spreading Lyme disease, anaplasmosis and babesiosis – bacterial infections that can sometimes cause serious and long-lasting illness. 

“There is a strong public desire for ‘natural’ means of killing and repelling ticks,” says microbiologist Stephen Rich, executive director of the New England Center of Excellence in Vector-borne Diseases (NEWVEC) at the University of Massachusetts Amherst, one of four universities funded by the Centers for Disease Control and Prevention (CDC) to lead vector-borne disease research.   

Different tick species feed off different vertebrates, explains Eric Siegel, lead author of the research published in the journal PLOS One and a doctoral student at NEWVEC. “Some animals are good hosts, and some are bad,” he says.

The sebaceous glands of horses and donkeys create secretions that keep their skin moist and include allomones, or chemical substances that affect the behavior of other plant and animal species. Previous research has shown that ticks that feed off horses but not donkeys will be repelled from horses when the horses’ smell is masked using one of the compounds secreted by donkey skin, known as (E)-2-octenal.

“It’s one of the different smells that you find on a donkey that you don’t find on a horse,” Siegel says. “So to ticks, the horse doesn’t smell like the host they’re used to. The ticks don’t like it, and so they won’t feed on it. Our assessment that we can repel ticks with this compound means that in theory we could either put it on ourselves or put it on dogs, and the ticks will not want to go near it.”

In the lab, Siegel and team showed that they could prevent deer ticks from moving from point A to point B when octenal is placed between the points. “It was as effective or more so than DEET, and it was even more effective with male ticks than females,” Siegel says.

The experiments were carried out in 2023, when a group of high school students were participating in a 10-week summer program in Rich’s Laboratory of Medical Zoology.  “A cool part of this paper is that four of the authors were high school students,” says Rich, senior author. The co-authors are Sophia Goodnow, Elizabeth MacLeod, Sarah Nicolson and Lucy Thompson. “They set up and did the preliminary experiments on their own,” Siegel says. 

The researchers are collaborating with Gearjump Technologies, which addresses complex global problems in healthcare, vector control and plant protection, to work on the development of a deer tick repellent with octenal as the active ingredient. In addition to repelling ticks from people, octenal might be turned into something that could control deer tick populations in the outdoors. 

“One avenue is, can we substitute the use of pesticides and use this in the environment to repel ticks?” Siegel says. 

NEWVEC was funded in 2022 with a $10 million, five-year award from the CDC. It brings together academic communities, public health practitioners, mosquito control and extension professionals, and wildlife biologists, as well as residents and visitors across the Northeast. Academic partners include Vermont State University, the University of Maine, University of New Hampshire, University of Rhode Island and Western Connecticut State University. 

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Journal

PLOS One

DOI

10.1371/journal.pone.0317975 

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Exploiting a natural instance of vertebrate-posed chemical aposematism for tick bite prevention: Repellency of Ixodes scapularis with (E)-Oct-2-enal

 

Pennington Biomedical Research Center’s June Small Shifts focus: adding more fruits and vegetables to diets

Pennington Biomedical Research Center

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Pennington Biomedical Research Center in Baton Rouge, La.

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Credit: Madison Page, PBRC

Pennington Biomedical Research Center announces the June Small Shifts campaign focus is adding more fruits and vegetables to diets. This month’s shift encourages individuals and families to make simple, sustainable changes that can lead to lasting improvements in overall health and wellness.

Fruits and vegetables are rich in essential nutrients, fiber, and antioxidants that support energy, mood, and immune function. By incorporating more of these nutrient-packed powerhouses into daily meals and snacks, people can make a big impact with just a small shift. Whether it's adding a handful of berries to breakfast, snacking on carrot sticks, or incorporating a side salad into a lunch, small changes can lead to big benefits.

Here are a few easy ways to start adding more fruits and vegetables now:

• Smoothie Boost: Start the day with a vibrant fruit and vegetable smoothie. Try blending spinach, banana, and berries for a delicious and nutritious kick-start to your morning.
• Snack Smart: Keep sliced vegetables like carrots, cucumbers, and bell peppers on hand for quick, healthy snacks.
• Mealtime Makeover: Add an extra serving of vegetables to meals. Stir fresh or frozen vegetables into soups, stews, and pasta dishes.
• Fruit First: Swap out a usual dessert for a piece of fruit or a fruit salad.

Pennington Biomedical encourages the public to join the movement by sharing their own fruit-and-veggie-inspired creations on social media using the following hashtag: #SmallShifts.

To learn more about the campaign and get additional tips, visit https://www.pbrc.edu/smallshifts.

About the Pennington Biomedical Research Center

The Pennington Biomedical Research Center is at the forefront of medical discovery as it relates to understanding the triggers of obesity, diabetes, cardiovascular disease, cancer and dementia. Pennington Biomedical has the vision to lead the world in promoting metabolic health and eliminating metabolic disease through scientific discoveries that create solutions from cells to society. The center conducts basic, clinical, and population research, and is a campus in the LSU System.

The research enterprise at Pennington Biomedical includes over 600 employees within a network of 44 clinics and research laboratories, and 16 highly specialized core service facilities. Its scientists and physician/scientists are supported by research trainees, lab technicians, nurses, dietitians, and other support personnel. Pennington Biomedical is a globally recognized state-of-the-art research institution in Baton Rouge, Louisiana. For more information, see www.pbrc.edu.

GROK

Study finds teachers, students together can form own social constructions of thinking

Findings go beyond how teachers convey information to students, how class culture forms how students think about topics critically, engage with material

University of Kansas

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LAWRENCE — There is an old saying that teachers don’t tell students what to think, but what to think about. A new study from the University of Kansas found that even beyond helping students understand how to think through complex topics, a classroom can work with a teacher to develop its own social construction of thinking.

Teaching students how to think in critical, reflective and deliberate ways has long been an important part of public and literacy education. But there is a common assumption that teachers provide the knowledge and students are recipients on how to form these processes of thinking. 

Min-Young Kim, assistant professor of curriculum and teaching at KU, led a study in which she observed how a teacher in an eighth grade English language arts class engaged students in constructing how they thought about literature. Kim found the students and teacher socially constructed how they think about a poem through a process called “languaging.” The teacher held them accountable for how they think, and the process facilitated the students’ engagement and connection with the material.

A growing body of literature has focused on the nature of knowledge in various academic subjects, but there has been little study on how thinking processes are formed in each.

“As a learning community, every classroom is constructing what thinking means, even though they have curriculum, materials and other things they share,” Kim said. “I wanted to understand that better. How do we facilitate thinking as a learning community? Not many studies have examined that.”

To probe the question, Kim observed an eighth grade English language arts class as the teacher and students studied Henry Wadsworth Longfellow’s poem “The Witnesses.” Over several class sessions, the students read the poem, analyzed it, discussed their thoughts on the author’s intent, their reactions to it and more.

“Here and there the teacher used the term ‘thinking aloud’ in her classroom and framed thinking in different ways,” Kim said. “As the class moved on, I saw that thinking is something constructed, and I wanted to research that more and interviewed the teacher about thinking processes and how she teaches them.” 

Through observation and the interviews, Kim found the framework of “languaging” — using gestures, facial expressions and other forms of nonverbal communication along with speaking about the material — to be more useful than traditional views of language to construct how they thought about the poem.

In addition to the modeling of a way of thinking, the teacher held the students accountable for what they thought and how by asking them why they had certain thoughts, ideas and reactions or how they came to their conclusions. That led to students articulating their thoughts, explaining why they came to certain methods of thinking and how together they formed a method of thinking about the material and modeled it not only through their linguistic repertoire, but through posture, gestures and expressions.

Lastly, Kim noted that the teacher acknowledged the students’ ideas and contributions. She said yes to their ideas and added to them. In essence, this made the entire class co-authors in the construction of how they thought through and about the poem, Kim wrote in the study, which was published in the journal Reading Research Quarterly.

The findings show that languaging thinking aloud engages the students on a deeper level and makes them the authors of how the class thinks about the subject matter, instead of simply being told how to think about it.

“I am arguing in this study that with languaging thinking practice, students are not passive receivers. It’s not just transfer, but students are part of constructing what they think about in the class,” Kim said. “It’s more than the assumption of knowledge transfer. Instead, it’s a dynamic construction. They articulated their thinking practices, and the teacher acknowledged them.”

Kim, who has also studied how teachers teach argumentation, said future research could further examine how students use similar practices to construct how they think about class material in small group settings. Similar studies could also go beyond English to classes including science, history, arts, physical education and more to better understand how classroom culture influences how students thinking about various subject matter. 

Traditionally, research has focused on instruction and how best to convey knowledge to students, but not how they can contribute to the ways the class thinks about topics and thereby becomes more engaged in the material.

“I think this paper gives us a tool or framework to look at how we can analyze thinking construction in many different kinds of classrooms and what kind of thinking practices take place and what more needs to be done to engage students in the social construction of how they think,” Kim said.

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Journal

Reading Research Quarterly

DOI

10.1002/rrq.70008 

Method of Research

Observational study

Subject of Research

People

Article Title

Unpacking the Social Construction of Thinking Practices in the Secondary English Classroom: A Languaging Perspective