Articles | Volume 39, issue 5
https://doi.org/10.5194/angeo-39-849-2021
© Author(s) 2021. 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-39-849-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
24 Sep 2021
Regular paper |
| 24 Sep 2021
| 24 Sep 2021
Observations of sunlit N2+ aurora at high altitudes during the RENU2 flight
Pål Gunnar Ellingsen
CORRESPONDING AUTHOR
Department of Electrical Engineering, UiT The Arctic University of Norway, 8505 Narvik, Norway
Dag Lorentzen
Department of Arctic Geophysics, The University Centre in Svalbard, P.O. Box 156, 9171 Longyearbyen, Norway
Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, 5020 Bergen, Norway
David Kenward
Department of Physics and Astronomy, University of New Hampshire, Durham, NH 03824, USA
James H. Hecht
Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA, USA
J. Scott Evans
Computational Physics Inc., Springfield, VA, USA
Fred Sigernes
Department of Arctic Geophysics, The University Centre in Svalbard, P.O. Box 156, 9171 Longyearbyen, Norway
Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, 5020 Bergen, Norway
Marc Lessard
Department of Physics and Astronomy, University of New Hampshire, Durham, NH 03824, USA
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The total solar eclipse event on Svalbard on 20 March 2015 gave us a unique opportunity to image the upper parts of the Sun's atmosphere. A novel image accumulation filter technique is presented that is capable of distinguishing features such as loops, spicules, plumes, and prominences from intense and blurry video recordings of the chromosphere.
Related subject area
Subject: Earth's ionosphere & aeronomy | Keywords: Auroral ionosphere
First observations of continuum emission in dayside aurora
Leaping and vortex motion of the shock aurora toward the late evening sector observed on 26 February 2023
Observations of traveling ionospheric disturbances driven by gravity waves from sources in the upper and lower atmosphere
Application of generalized aurora computed tomography to the EISCAT_3D project
Auroral breakup detection in all-sky images by unsupervised learning
Three-dimensional ionospheric conductivity associated with pulsating auroral patches: reconstruction from ground-based optical observations
The altitude of green OI 557.7 nm and blue N2+ 427.8 nm aurora
Reconstruction of precipitating electrons and three-dimensional structure of a pulsating auroral patch from monochromatic auroral images obtained from multiple observation points
Spatio-temporal development of large-scale auroral electrojet currents relative to substorm onsets
Validation of SSUSI-derived auroral electron densities: comparisons to EISCAT data
Noora Partamies, Rowan Dayton-Oxland, Katie Herlingshaw, Ilkka Virtanen, Bea Gallardo-Lacourt, Mikko Syrjäsuo, Fred Sigernes, Takanori Nishiyama, Toshi Nishimura, Mathieu Barthelemy, Anasuya Aruliah, Daniel Whiter, Lena Mielke, Maxime Grandin, Eero Karvinen, Marjan Spijkers, and Vincent Ledvina
EGUsphere, https://doi.org/10.5194/egusphere-2024-3669, https://doi.org/10.5194/egusphere-2024-3669, 2024
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We studied the first broad band emissions, called continuum, in the dayside aurora. They are similar to STEVE with white, pale pink or mauve coloured light. But unlike STEVE, they follow the dayside aurora forming rays and other dynamic shapes. We used ground optical and radar observations and found evidence of heating and upwelling of both plasma and neutral air. This study provides new information on conditions for continuum emission, but its understanding will require further work.
Sota Nanjo, Masatoshi Yamauchi, Magnar Gullikstad Johnsen, Yoshihiro Yokoyama, Urban Brändström, Yasunobu Ogawa, Anna Naemi Willer, and Keisuke Hosokawa
EGUsphere, https://doi.org/10.5194/egusphere-2024-3277, https://doi.org/10.5194/egusphere-2024-3277, 2024
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Our research explored the "shock aurora," caused by the impact of solar wind particles on Earth's magnetic field. On February 26, 2023, we observed this rare event on the nightside, where such observations are difficult. Ground-based cameras revealed new structural features, including undulating and jumping patterns. These results provide fresh insights into the complex interactions between the solar wind and Earth's magnetosphere, enhancing our understanding of space weather effects.
Paul Prikryl, David R. Themens, Jaroslav Chum, Shibaji Chakraborty, Robert G. Gillies, and James M. Weygand
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2024-6, https://doi.org/10.5194/angeo-2024-6, 2024
Revised manuscript accepted for ANGEO
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Travelling ionospheric disturbances are plasma density fluctuations usually driven by atmospheric gravity waves in the neutral atmosphere. The aim of this study is to attribute multi-instrument observations of travelling ionospheric disturbances to gravity waves generated in the upper atmosphere at high latitudes or gravity waves generated by tropospheric weather systems at mid latitudes.
Yoshimasa Tanaka, Yasunobu Ogawa, Akira Kadokura, Takehiko Aso, Björn Gustavsson, Urban Brändström, Tima Sergienko, Genta Ueno, and Satoko Saita
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We present via simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized-aurora computed tomography (G-ACT) to modeled multiple auroral images and ionospheric electron density data. It is demonstrated that G-ACT provides better reconstruction results than the normal ACT and can interpolate ionospheric electron density at a much higher spatial resolution than observed by the EISCAT_3D radar.
Noora Partamies, Bas Dol, Vincent Teissier, Liisa Juusola, Mikko Syrjäsuo, and Hjalmar Mulders
Ann. Geophys., 42, 103–115, https://doi.org/10.5194/angeo-42-103-2024, https://doi.org/10.5194/angeo-42-103-2024, 2024
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Auroral imaging produces large amounts of image data that can no longer be analyzed by visual inspection. Thus, every step towards automatic analysis tools is crucial. Previously supervised learning methods have been used in auroral physics, with a human expert providing ground truth. However, this ground truth is debatable. We present an unsupervised learning method, which shows promising results in detecting auroral breakups in the all-sky image data.
Mizuki Fukizawa, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Tero Raita, and Kirsti Kauristie
Ann. Geophys., 41, 511–528, https://doi.org/10.5194/angeo-41-511-2023, https://doi.org/10.5194/angeo-41-511-2023, 2023
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We use computed tomography to reconstruct the three-dimensional distributions of the Hall and Pedersen conductivities of pulsating auroras, a key research target for understanding the magnetosphere–ionosphere coupling process. It is suggested that the high-energy electron precipitation associated with pulsating auroras may have a greater impact on the closure of field-aligned currents in the ionosphere than has been previously reported.
Daniel K. Whiter, Noora Partamies, Björn Gustavsson, and Kirsti Kauristie
Ann. Geophys., 41, 1–12, https://doi.org/10.5194/angeo-41-1-2023, https://doi.org/10.5194/angeo-41-1-2023, 2023
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We measured the height of green and blue aurorae using thousands of camera images recorded over a 7-year period. Both colours are typically brightest at about 114 km altitude. When they peak at higher altitudes the blue aurora is usually higher than the green aurora. This information will help other studies which need an estimate of the auroral height. We used a computer model to explain our observations and to investigate how the green aurora is produced.
Mizuki Fukizawa, Takeshi Sakanoi, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Björn Gustavsson, Kirsti Kauristie, Alexander Kozlovsky, Tero Raita, Urban Brändström, and Tima Sergienko
Ann. Geophys., 40, 475–484, https://doi.org/10.5194/angeo-40-475-2022, https://doi.org/10.5194/angeo-40-475-2022, 2022
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The pulsating auroral generation mechanism has been investigated by observing precipitating electrons using rockets or satellites. However, it is difficult for such observations to distinguish temporal changes from spatial ones. In this study, we reconstructed the horizontal 2-D distribution of precipitating electrons using only auroral images. The 3-D aurora structure was also reconstructed. We found that there were both spatial and temporal changes in the precipitating electron energy.
Sebastian Käki, Ari Viljanen, Liisa Juusola, and Kirsti Kauristie
Ann. Geophys., 40, 107–119, https://doi.org/10.5194/angeo-40-107-2022, https://doi.org/10.5194/angeo-40-107-2022, 2022
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During auroral substorms, the ionospheric electric currents change rapidly, and a large amount of energy is dissipated. We combine ionospheric current data derived from the Swarm satellite mission with the substorm database from the SuperMAG ground magnetometer network. We obtain statistics of the strength and location of the currents relative to the substorm onset. Our results show that low-earth orbit satellites give a coherent picture of the main features in the substorm current system.
Stefan Bender, Patrick J. Espy, and Larry J. Paxton
Ann. Geophys., 39, 899–910, https://doi.org/10.5194/angeo-39-899-2021, https://doi.org/10.5194/angeo-39-899-2021, 2021
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The coupling of the atmosphere to the space environment has become recognized as an important driver of atmospheric chemistry and dynamics. We have validated the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) products for average electron energy and electron energy flux by comparison to EISCAT electron density profiles. The good agreement shows that SSUSI far-UV observations can be used to provide ionization rate profiles throughout the auroral region.
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Short summary
Using the RENU2 rocket and ground-based instruments, we show that significant parts of the blue aurora above Svalbard at the time of launch were sunlit aurora. A sunlit aurora occurs when nitrogen molecules are ionised by extreme UV sunlight and subsequently hit by electrons from the Sun, resulting in blue and violet emissions. Understanding the source of an auroral emission gives insight into the interaction between the Sun and the Earth's upper atmosphere.
Using the RENU2 rocket and ground-based instruments, we show that significant parts of the blue...
