Student色视频下载檚 research upends understanding of upper atmospheric wind
Rod Boyce
907-474-7185
Nov. 9, 2021
Space physicist Mark Conde had been seeing something curious in his atmospheric research data since the 1990s.
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 色视频下载 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 色视频下载. 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色视频下载檚 surface. And that means the occasional stalling of the cross-polar jet won色视频下载檛 be noticed on the surface or affect life here.
滨迟补苍颈色视频下载檚 on the topic, co-authored by Conde, was published in September by the Journal of Geophysical Research: Space Physics and in the American Geophysical Union magazine Eos.
Rajan Itani
滨迟补苍颈色视频下载檚 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 色视频下载 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色视频下载檚 dayside to its nightside and delivers it toward the equator, where it dissipates. Sometimes, according to 滨迟补苍颈色视频下载檚 research, the forces driving the wind aren色视频下载檛 strong enough to push it through the background atmosphere on the Earth色视频下载檚 night side.
色视频下载淎ll 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,色视频下载 said Conde, who is a professor in the UAF Department of Physics. 色视频下载淭here should be quite a strong flow extending far equatorward, but we find that it basically just hits a wall over 色视频下载 on some occasions. It really should continue and spill out just like the models say.色视频下载
Mark Conde
But what causes this stalling? That hasn色视频下载檛 been resolved yet. 滨迟补苍颈色视频下载檚 paper does offer a correlation, however: A review of seven years of data shows a 色视频下载渟trong influence色视频下载 from solar activity. Thermospheric wind stalling is most likely to occur during solar minimum, the period of low disturbance on the sun色视频下载檚 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 色视频下载.
"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,色视频下载 he said.
Conde published a paper in 2018 that noted the thermospheric wind stalling; however, 滨迟补苍颈色视频下载檚 paper expands on that work in more detail.
色视频下载淭raining the next generation of scientists is a major objective of the United States色视频下载 premier research institution, the National Science Foundation, which funded the work,色视频下载 Conde said. 色视频下载淎s a result, quite a bit of leading-edge research is done by graduate students. I am very pleased to see Rajan色视频下载檚 work in this area recognized by the American Geophysical Union.色视频下载
The mention in Eos was a career first for Itani. The magazine notes that fewer than 2% of papers receive such attention.
色视频下载淚 am delighted that our paper has been featured as an editor's highlight in Eos,色视频下载 Itani said. 色视频下载淚t is a proud moment in my career in space physics, as it marks my first paper being promoted. I am thankful to my adviser, Dr. Mark Conde, for suggesting the research topic and for his endless support and encouragement.色视频下载
ADDITIONAL CONTACTS: Rajan Itani, ritani@alaska.edu; Mark Conde, 907- 474-7741, mgconde@alaska.edu.
NOTE TO EDITORS: Photographs of Rajan Itani and Mark Conde are available with this press release at the .
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