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  • richardmitnick 5:03 pm on November 10, 2021 Permalink | Reply
    Tags: "Student’s research upends understanding of upper atmospheric wind", , , , Space physics, The cross-polar jet,   

    From The University of Alaska-Fairbanks (US) : “Student’s research upends understanding of upper atmospheric wind” 

    From The University of Alaska-Fairbanks (US)

    Nov. 9, 2021
    Rod Boyce
    rodcboyce@gmail.com
    907-474-7185

    Space physicist Mark Conde had been seeing something curious in his atmospheric research data since the 1990s.

    1
    Rajan Itani. Photo by Daniel Walker.

    Three years ago, he realized the odd behavior of extreme upper-level wind was a real phenomenon and not a problem with instrumentation. He chose to hand the mystery to his research student, Rajan Itani, who is pursuing a doctorate in physics at the University of Alaska Fairbanks.

    Itani confirmed that the cross-polar jet, a well-known wind in the upper atmosphere, sometimes inexplicably stops or is deflected or reversed when it reaches the region above Alaska. The finding upends previous understanding of the wind’s behavior and has implications for spacecraft orbits, space debris avoidance, ionospheric storm modeling and our understanding about the transport of air in the thermosphere. That portion of the atmosphere is far less dense, almost to a vacuum, compared to air at the Earth’s surface. And that means the occasional stalling of the cross-polar jet won’t be noticed on the surface or affect life here.

    Itani’s paper on the topic, co-authored by Conde, was published in September by the Journal of Geophysical Research: Space Physics and included in the editor’s highlights in the American Geophysical Union magazine Eos.

    Itani’s research at the UAF Geophysical Institute, with assistance from Conde and conducted mostly with data from UAF’s Poker Flat Research Range, focused only on the Alaska region. But it is likely that the cross-polar jet would also stall elsewhere on the globe at high latitudes as the wind emerges from the polar cap around midnight.

    Conde and Itani were studying the upper thermosphere, the region of atmosphere above 90 miles altitude.

    This cross-polar jet carries the thin air in this region over the North Pole from the Earth’s dayside to its nightside and delivers it toward the equator, where it dissipates. Sometimes, according to Itani’s research, the forces driving the wind aren’t strong enough to push it through the background atmosphere on the Earth’s night side.

    “All of the computer models say that this wind spills out quite some distance toward the equator and then eventually slows and blends into the background flow, just like traffic merging onto a highway,” said Conde, who is a professor in the UAF Department of Physics. “There should be quite a strong flow extending far equatorward, but we find that it basically just hits a wall over Alaska on some occasions. It really should continue and spill out just like the models say.”

    2
    Mark Conde. Photo by Daniel Walker.

    But what causes this stalling? That hasn’t been resolved yet. Itani’s paper does offer a correlation, however: A review of seven years of data shows a “strong influence” from solar activity. Thermospheric wind stalling is most likely to occur during solar minimum, the period of low disturbance on the sun’s surface.

    Conde had actually seen the wind stalling in data at various times since the late 1990s when he began studying the impact of auroral displays on thermospheric winds above Alaska.

    “Over the years as we’ve run multiple instruments and combined the data from those many instruments, I eventually just came to understand that what we were seeing was a real phenomenon,” he said.

    Conde published a paper in 2018 that noted the thermospheric wind stalling; however, Itani’s paper expands on that work in more detail.

    “Training the next generation of scientists is a major objective of the United States’ premier research institution, The National Science Foundation (US), which funded the work,” Conde said. “As a result, quite a bit of leading-edge research is done by graduate students. I am very pleased to see Rajan’s work in this area recognized by the American Geophysical Union.”

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The The University of Alaska-Fairbanks (US) is a public land-grant research university in College, Alaska; a suburb of Fairbanks. It is a flagship campus of the University of Alaska system. UAF was established in 1917 and opened for classes in 1922. Originally named the Alaska Agricultural College and School of Mines, it became the University of Alaska in 1935. Fairbanks-based programs became the University of Alaska Fairbanks in 1975.

    University of Alaska-Fairbanks is classified among “R2: Doctoral Universities – High research activity”. It is home to several major research units, including the Agricultural and Forestry Experiment Station; the Geophysical Institute, which operates the Poker Flat Research Range and several other scientific centers; the Alaska Center for Energy and Power; the International Arctic Research Center; the Institute of Arctic Biology; the Institute of Marine Science; and the Institute of Northern Engineering. Located just 200 miles (320 km) south of the Arctic Circle, the Fairbanks campus’ unique location favors Arctic and northern research. UAF’s research specialties are renowned worldwide, most notably Arctic biology, Arctic engineering, geophysics, supercomputing, Ethnobotany and Alaska Native studies. The University of Alaska Museum of the North is also on the Fairbanks campus.

    In addition to the Fairbanks campus, University of Alaska-Fairbanks encompasses six rural and urban campuses: Bristol Bay Campus in Dillingham; Chukchi Campus in Kotzebue; the Fairbanks-based Interior Alaska Campus, which serves the state’s rural Interior; Kuskokwim Campus in Bethel; Northwest Campus in Nome; and the UAF Community and Technical College, with headquarters in downtown Fairbanks. UAF is also the home of UAF eCampus, which offers fully online programs.

    In fall 2017, University of Alaska-Fairbanks enrolled 8,720 students. Of those students, 58% were female and 41% were male; 87.8% were undergraduates, and 12.2% were graduate students. As of May 2018, 1,352 students had graduated during the immediately preceding summer, fall and spring semesters.

    Research units

    University of Alaska-Fairbanks is Alaska’s primary research university, conducting more than 90% of University of Alaska system research. Research activities are organized into several institutes and centers:

    the Geophysical Institute, established in 1946 by an act of Congress, specializes in seismology, volcanology and aeronomy, among other fields.
    the International Arctic Research Center researches the circumpolar North and the causes and effects of climate change.
    the Institute of Northern Engineering, an arm of the College of Engineering and Mines, conducts research in many different areas of engineering.
    the Research Computing Systems unit, located within the Geophysical Institute, is the high-performance computing unit of UAF.
    the Alaska Agricultural and Forestry Experiment Station conducts research focused on solving problems related to agriculture and forest sciences.
    the Institute of Arctic Biology conducts research focused on high-latitude biological systems.
    the Robert G. White Large Animal Research Station conducts long-term research with muskoxen, reindeer and cattle.
    the Institute of Marine Science, a branch of the College of Fisheries and Ocean Sciences, investigates topics in oceanography, marine biology, and fisheries.
    the R/V Sikuliaq, a 261-foot ice-resistant ship outfitted with modern scientific equipment, is operated by the College of Fisheries and Ocean Sciences for the National Science Foundation (US).

     
  • richardmitnick 7:58 am on May 10, 2021 Permalink | Reply
    Tags: "Physicists describe new type of aurora", , Space physics, University of Calgary (CS), University of Iowa (US)   

    From University of Iowa (US) with University of Calgary (CA): “Physicists describe new type of aurora” 

    From University of Iowa (US)

    2021.05.06

    Richard Lewis
    Office of Strategic Communication
    319-384-0012
    richard-c-lewis@uiowa.edu

    Discovery comes from reanalysis of two-decade-old video.


    Physicists describe new type of aurora.
    The famed northern and southern lights still hold secrets. In a new study, physicists led by the University of Iowa (US) describe a new phenomenon they call “diffuse auroral erasers,” in which patches of the background glow are blotted out, then suddenly intensify and reappear.

    1
    Diffuse auroral erasers. Credit: David Knudsen via University of Iowa.

    For millennia, humans in the high latitudes have been enthralled by auroras—the northern and southern lights. Yet even after all that time, it appears the ethereal, dancing ribbons of light above Earth still hold some secrets.

    In a new study, physicists led by the University of Iowa report a new feature to Earth’s atmospheric light show. Examining video taken nearly two decades ago, the researchers describe multiple instances where a section of the diffuse aurora—the faint, background-like glow accompanying the more vivid light commonly associated with auroras—goes dark, as if scrubbed by a giant blotter. Then, after a short period of time, the blacked-out section suddenly reappears.

    The researchers say the behavior, which they call “diffuse auroral erasers,” has never been mentioned in the scientific literature. The findings appear in the Journal of Geophysical Research Space Physics.

    Auroras occur when charged particles flowing from the sun—called the solar wind—interact with Earth’s protective magnetic bubble. Some of those particles escape and fall toward our planet, and the energy released during their collisions with gases in Earth’s atmosphere generate the light associated with auroras.

    “The biggest thing about these erasers that we didn’t know before but know now is that they exist,” says Allison Jaynes, assistant professor in the Department of Physics and Astronomy at Iowa and study co-author. “It raises the question: Are these a common phenomenon that has been overlooked, or are they rare?

    “Knowing they exist means there is a process that is creating them,” Jaynes continues, “and it may be a process that we haven’t started to look at yet because we never knew they were happening until now.”


    Diffuse auroral erasers.

    It was on March 15, 2002, that David Knudsen, a physicist at the University of Calgary (CA), set up a video camera in Churchill, a town along Hudson Bay in Canada, to film auroras. Knudsen’s group was a little disheartened; the forecast called for clear, dark skies—normally perfect conditions for viewing auroras—but no dazzling illumination was happening. Still, the team was using a camera specially designed to capture low-level light, much like night-vision goggles.

    Though the scientists saw only mostly darkness as they gazed upward with their own eyes, the camera was picking up all sorts of auroral activity, including an unusual sequence where areas of the diffuse aurora disappeared, then came back.

    Knudsen, looking at the video as it was being recorded, scribbled in his notebook, “pulsating ‘black out’ diffuse glow, which then fills in over several seconds.”

    “What surprised me, and what made me write it in the notebook, is when a patch brightened and turned off, the background diffuse aurora was erased. It went away,” says Knudsen, a Fort Dodge, Iowa, native who has studied aurora for more than 35 years and is a co-author on the study. “There was a hole in the diffuse aurora. And then that hole would fill back in after a half-minute or so. I had never seen something like that before.”

    The note lay dormant, and the video unstudied, until Iowa’s Jaynes handed it to graduate student Riley Troyer to investigate. Jaynes learned about Knudsen’s recording at a scientific meeting in 2010 and referenced the eraser note in her doctoral thesis on diffuse aurora a few years later. Now on the faculty at Iowa, she wanted to learn more about the phenomenon.

    “I knew there was something there. I knew it was different and unique,” says Jaynes, assistant professor in the Department of Physics and Astronomy. “l had some ideas how it could be analyzed, but I hadn’t done that yet. I handed it to Riley, and he went much further with it by figuring out his own way to analyze the data and produce some significant conclusions.”

    2
    Notes written by David Knudsen, a physicist at the University of Calgary, in 2002 make mention of a “pulsating ‘black out’ diffuse glow, which then fills in over several seconds.”

    Troyer, from Fairbanks, Alaska, took up the assignment with gusto.

    “I’ve seen hundreds of auroras growing up,” says Troyer, who is in his third year of doctoral studies at Iowa. “They’re part of my heritage, something I can study while keeping ties to where I’m from.”

    Troyer created a software program to key in on frames in the video when the faint erasers were visible. In all, he cataloged 22 eraser events in the two-hour recording.

    “The most valuable thing we found is showing the time that it takes for the aurora to go from an eraser event (when the diffuse aurora is blotted out) to be filled or colored again,” says Troyer, who is the paper’s corresponding author, “and how long it takes to go from that erased state back to being diffuse aurora. Having a value on that will help with future modeling of magnetic fields.”

    Jaynes says learning about diffuse auroral erasers is akin to studying DNA to understand the entire human body.

    “Particles that fall into our atmosphere from space can affect our atmospheric layers and our climate,” Jaynes says. “While particles with diffuse aurora may not be the main cause, they are smaller building blocks that can help us understand the aurora system as a whole, and may broaden our understanding how auroras happen on other planets in our solar system.”

    Study co-authors are Sarah Jones, from NASA Goddard Space Flight Center (US) and who was part of Knudsen’s team in Churchill, and Trond Trondsen, with Keo Scientific Ltd., who built the camera that filmed the diffuse aurora.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The University of Iowa (US) is a public research university in Iowa City, Iowa. Founded in 1847, it is the oldest and the second-largest university in the state. The University of Iowa is organized into 12 colleges offering more than 200 areas of study and seven professional degrees.

    On an urban 1,880-acre campus on the banks of the Iowa River, the University of Iowa is classified among “R1: Doctoral Universities – Very high research activity”. The university is best known for its programs in health care, law, and the fine arts, with programs ranking among the top 25 nationally in those areas. The university was the original developer of the Master of Fine Arts degree and it operates the Iowa Writer’s Workshop, which has produced 17 of the university’s 46 Pulitzer Prize winners. Iowa is a member of the Association of American Universities, the Universities Research Association, and the Big Ten Academic Alliance.

    Among American universities, the University of Iowa was the first public university to open as coeducational, opened the first coeducational medical school, and opened the first Department of Religious Studies at a public university. The University of Iowa’s 33,000 students take part in nearly 500 student organizations. Iowa’s 22 varsity athletic teams, the Iowa Hawkeyes, compete in Division I of the NCAA and are members of the Big Ten Conference. The University of Iowa alumni network exceeds 250,000 graduates.

     
  • richardmitnick 1:58 pm on March 2, 2017 Permalink | Reply
    Tags: , , Jicamarca Radio Observatory, , , Space physics   

    From Eos: “After Decades, High-Altitude Observations Revived at Jicamarca” 

    AGU bloc

    AGU
    Eos news bloc

    Eos

    3.2.17
    Mark Zastrow

    1
    Dipoles of the telescope at Jicamarca Radio Observatory near Lima, Peru. Construction of the observatory was completed in 1962, around the time this photo was taken. Credit: Alastair Philip Wiper/VIEW

    When the Jicamarca Radio Observatory made its first observations of Earth’s ionosphere in the early 1960s, it was one of the most impressive facilities in the nascent field of space physics. Its massive square array of dipole antennas was laid out in the Peruvian desert east of Lima, nearly 300 meters on each side. The enormous radar facility was designed to probe the ionosphere directly above Earth’s equator; electrons in the ionosphere scatter the radar beams, but a faint return signal gives an indication of their density.

    In its initial observing runs, scientists included measurements at very high altitudes, an exercise meant to map out the space surrounding Earth. They also pushed the facility to its limits, requiring powerful radar pulses from all four of its transmitters and many people to operate them. Soon, however, high-altitude operations were canceled; the last runs occurred in 1965.

    As the facility began to focus on more popular areas of research, the unpublished high-altitude records languished. Many were lost. The details of the observations and analysis—such as which filtering methods, if any, were used—faded away, limiting the surviving data’s usefulness. Eventually, the capability to reproduce them was lost, as transmitters fell offline and Jicamarca focused on targets closer to the ground.

    Today, more than 50 years later, interest in high-altitude observations is on the rise, this time driven by the desire to understand how plasma behaves during geomagnetic storms. Jicamarca remains one of the most important space physics radar facilities, and fortunately, recent upgrades have restored the facility’s ability to carry out high-altitude observations. On 31 May 2016, Jicamarca fired up its transmitters and focused its antennas on high-altitude incoherent scatter in a study conducted by Hysell et al.

    In a 24-hour period of observations, the team found that Jicamarca could profile the electron density up to an altitude of roughly 6300 kilometers. That’s high enough to usefully overlap with data from ground-based magnetometers, which can cover a range from roughly 3000 kilometers to 16,000 kilometers. The data analysis also revealed that different filtering methods did not change the results much, which makes it easier to interpret historical data.

    The authors used just two of Jicamarca’s four transmitters, all of which have been restored to operational status. Even with only two transmitters, the data quality was similar to the 1965 data, with a slightly better dynamic range. The team notes that future observations using all four transmitters will be more sensitive and should push the observatory’s range occasionally up to 10,000 kilometers. (Journal of Geophysical Research: Space Physics, https://doi.org/10.1002/2016JA023569, 2017)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
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