Articles | Volume 38, issue 2
https://doi.org/10.5194/angeo-38-481-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/angeo-38-481-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
08 Apr 2020
Regular paper |
| 08 Apr 2020
| 08 Apr 2020
AMPERE polar cap boundaries
Angeline G. Burrell
CORRESPONDING AUTHOR
Space Science Division, U.S. Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC, USA
Gareth Chisham
British Antarctic Survey, Cambridge, UK
Stephen E. Milan
Radio and Space Plasma Physics, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, UK
Liam Kilcommons
Ann and H.J. Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder, 2055 Regent Drive, Boulder, CO, USA
Yun-Ju Chen
Center for Space Sciences, Department of Physics, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX, USA
Evan G. Thomas
Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, USA
Brian Anderson
Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, USA
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Subject: Earth's ionosphere & aeronomy | Keywords: Polar ionosphere
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This paper presents an analysis of high-resolution optical and radar observations of a phenomenon called fragmented aurora-like emissions (FAEs) observed close to aurora in the high Arctic. The observations suggest that FAEs are not caused by high-energy electrons or protons entering the atmosphere along Earth's magnetic field and are, therefore, not aurora. The speeds of the FAEs and their internal dynamics were measured and used to evaluate theories for how the FAEs are produced.
Dimitry Pokhotelov, Isabel Fernandez-Gomez, and Claudia Borries
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During geomagnetic storms, enhanced solar wind and changes in the interplanetary magnetic field lead to ionisation anomalies across the polar regions. The superstorm of 20 November 2003 was one of the largest events in recent history. Numerical simulations of ionospheric dynamics during the storm are compared with plasma observations to understand the mechanisms forming the polar plasma anomalies. The results are important for understanding and forecasting space weather in polar regions.
Joshua Dreyer, Noora Partamies, Daniel Whiter, Pål G. Ellingsen, Lisa Baddeley, and Stephan C. Buchert
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Small-scale auroral features are still being discovered and are not well understood. Where aurorae are caused by particle precipitation, the newly reported fragmented aurora-like emissions (FAEs) seem to be locally generated in the ionosphere (hence,
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Luke A. Jenner, Alan G. Wood, Gareth D. Dorrian, Kjellmar Oksavik, Timothy K. Yeoman, Alexandra R. Fogg, and Anthea J. Coster
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The boundary of regions with a plasma density much lower than background was investigated in the northern polar cap using observations of ionospheric plasma density. Similar regions with an above-background density have been linked to fluctuations in phase and amplitude in radio waves traversing the density gradient at their boundary. These fluctuations were absent through the gradient in the below-background regions; thus, a minimum of both density and gradient are required for scintillation.
Shucan Ge, Hailong Li, Tong Xu, Mengyan Zhu, Maoyan Wang, Lin Meng, Safi Ullah, and Abdur Rauf
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Short summary
The Earth's polar upper atmosphere changes along with the magnetic field, other parts of the atmosphere, and the Sun. When studying these changes, knowing the polar region that the data come from is vital, as different processes dominate the area where the aurora is and poleward of the aurora (the polar cap). The boundary between these areas is hard to find, so this study used a different boundary and figured out how they are related. Future studies can now find their polar region more easily.
The Earth's polar upper atmosphere changes along with the magnetic field, other parts of the...
