Articles | Volume 43, issue 2
https://doi.org/10.5194/angeo-43-349-2025
© Author(s) 2025. 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-43-349-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| Highlight paper
| 
03 Jul 2025
Regular paper | Highlight paper |
| 03 Jul 2025
| 03 Jul 2025
First observations of continuum emission in dayside aurora
Noora Partamies
CORRESPONDING AUTHOR
Department of Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
Rowan Dayton-Oxland
Department of Physics and Astronomy, University of Southampton, Southampton, UK
Katie Herlingshaw
Department of Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
Ilkka Virtanen
Space Physics and Astronomy, University of Oulu, Oulu, Finland
Bea Gallardo-Lacourt
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
Department of Physics, The Catholic University of America, NE Washington, DC 20064, USA
Mikko Syrjäsuo
Department of Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
Fred Sigernes
Department of Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
Takanori Nishiyama
National Institute of Polar Research, Tokyo, Japan
Toshi Nishimura
Department of Electrical and Computer Engineering and Center for Space Physics, Boston University, Boston, MA, USA
Mathieu Barthelemy
IPAG, Université Grenoble Alpes, CNRS, Grenoble, France
Anasuya Aruliah
Department of Physics and Astronomy, University College London, London, UK
Daniel Whiter
Department of Physics and Astronomy, University of Southampton, Southampton, UK
Lena Mielke
Department of Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
Maxime Grandin
Finnish Meteorological Institute, Helsinki, Finland
Eero Karvinen
URSA, Skywarden service, Finland
Marjan Spijkers
Noorderlicht en meer, Zomerdijkstraat 23, 8043 HW Zwolle, Netherlands
Vincent E. Ledvina
Geophysical Institute, University of Alaska Fairbanks, Fairbanks, Alaska, USA
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Maxime Grandin, Liisa Juusola, Noora Partamies, Emma Bruus, Joona Rautiainen, Donna Lach, Jia Jia, Max van de Kamp, Eero Karvinen, Kirsti Kauristie, and Theresa Hoppe
EGUsphere, https://doi.org/10.5194/egusphere-2025-5374, https://doi.org/10.5194/egusphere-2025-5374, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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Dune aurora is an intriguing phenomenon recently discovered thanks to citizen science. It is a dim, diffuse auroral form exhibiting wave-like stripes of brighter emission. We carry out the first statistical study of dune aurora, using 289 observation reports submitted to the Skywarden database by citizen scientists from Europe, North America, and Oceania. We find that dunes are an evening phenomenon, most often reported in March and October and associated with currents in the auroral atmosphere.
Rumi Nakamura, Thierry Dudok de Wit, Geraint H. Jones, Matt G. G. T. Taylor, Nicolas André, Charlotte Goetz, Lina Z. Hadid, Laura A. Hayes, Heli Hietala, Caitríona M. Jackman, Larry Kepko, Aurélie Marchaudon, Adam Masters, Mathew Owens, Noora Partamies, Stefaan Poedts, Jonathan Rae, Yuri Shprits, Manuela Temmer, Daniel Verscharen, and Robert F. Wimmer-Schweingruber
Ann. Geophys., 43, 855–879, https://doi.org/10.5194/angeo-43-855-2025, https://doi.org/10.5194/angeo-43-855-2025, 2025
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Heliophysics spans a wide range of disciplines covering the study of the Sun and the different Solar System bodies, such as Earth and other planets, moons, comets, and asteroids, and their interactions with the Sun, focusing on plasma and atmospheric processes. A grass-roots effort has been recently started toward establishing a European Heliophysics Community (https://www.heliophysics.eu/). This white paper outlines the motivation, priorities, and a future vision of Heliophysics in Europe.
Maxime Grandin, Emma Bruus, Vincent E. Ledvina, Noora Partamies, Mathieu Barthelemy, Carlos Martinis, Rowan Dayton-Oxland, Bea Gallardo-Lacourt, Yukitoshi Nishimura, Katie Herlingshaw, Neethal Thomas, Eero Karvinen, Donna Lach, Marjan Spijkers, and Calle Bergstrand
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We carried out a citizen science study of aurora sightings and technological disruptions experienced during the extreme geomagnetic storm of 10 May 2024. We collected reports from 696 observers from over 30 countries via an online survey, supplemented with observations logged in the Skywarden database. We found that the aurora was seen from exceptionally low latitudes and had very bright red and pink hues, suggesting that high fluxes of low-energy electrons from space entered the atmosphere.
Maxime Grandin, Noora Partamies, and Ilkka I. Virtanen
Ann. Geophys., 42, 355–369, https://doi.org/10.5194/angeo-42-355-2024, https://doi.org/10.5194/angeo-42-355-2024, 2024
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Auroral displays typically take place at high latitudes, but the exact latitude where the auroral breakup occurs can vary. In this study, we compare the characteristics of the fluxes of precipitating electrons from space during auroral breakups occurring above Tromsø (central part of the auroral zone) and above Svalbard (poleward boundary of the auroral zone). We find that electrons responsible for the aurora above Tromsø carry more energy than those precipitating above Svalbard.
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.
Noora Partamies, Daniel Whiter, Kirsti Kauristie, and Stefano Massetti
Ann. Geophys., 40, 605–618, https://doi.org/10.5194/angeo-40-605-2022, https://doi.org/10.5194/angeo-40-605-2022, 2022
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We investigate the local time behaviour of auroral structures and emission height. Data are collected from the Fennoscandian Lapland and Svalbard latitutes from 7 identical auroral all-sky cameras over about 1 solar cycle. The typical peak emission height of the green aurora varies from 110 km on the nightside to about 118 km in the morning over Lapland but stays systematically higher over Svalbard. During fast solar wind, nightside emission heights are 5 km lower than during slow solar wind.
Pekka T. Verronen, Antti Kero, Noora Partamies, Monika E. Szeląg, Shin-Ichiro Oyama, Yoshizumi Miyoshi, and Esa Turunen
Ann. Geophys., 39, 883–897, https://doi.org/10.5194/angeo-39-883-2021, https://doi.org/10.5194/angeo-39-883-2021, 2021
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This paper is the first to simulate and analyse the pulsating aurorae impact on middle atmosphere on monthly/seasonal timescales. We find that pulsating aurorae have the potential to make a considerable contribution to the total energetic particle forcing and increase the impact on upper stratospheric odd nitrogen and ozone in the polar regions. Thus, it should be considered in atmospheric and climate simulations.
Joshua Dreyer, Noora Partamies, Daniel Whiter, Pål G. Ellingsen, Lisa Baddeley, and Stephan C. Buchert
Ann. Geophys., 39, 277–288, https://doi.org/10.5194/angeo-39-277-2021, https://doi.org/10.5194/angeo-39-277-2021, 2021
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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,
aurora-like). We analyse data from multiple instruments located near Longyearbyen to derive their main characteristics. They seem to occur as two types in a narrow altitude region (individually or in regularly spaced groups).
Emma Bland, Fasil Tesema, and Noora Partamies
Ann. Geophys., 39, 135–149, https://doi.org/10.5194/angeo-39-135-2021, https://doi.org/10.5194/angeo-39-135-2021, 2021
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A total of 10 Super Dual Auroral Radar Network radars were used to estimate the horizontal area over which energetic electrons impact the atmosphere at 70–100 km altitude during pulsating aurorae (PsAs). The impact area varies significantly from event to event. Approximately one-third extend over 12° of magnetic latitude, while others are highly localised. Our results could be used to improve the forcing used in atmospheric/climate models to properly capture the energy contribution from PsAs.
Sota Nanjo, Katie Herlingshaw, Tima Sergienko, Gaël Cessateur, Noora Partamies, Magnar G. Johnsen, Keisuke Hosokawa, Hervé Lamy, Yasunobu Ogawa, Antti Kero, Shin-ichiro Oyama, and Masatoshi Yamauchi
Ann. Geophys., 44, 63–84, https://doi.org/10.5194/angeo-44-63-2026, https://doi.org/10.5194/angeo-44-63-2026, 2026
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During the New Year’s Day storm of 2025, we observed rare auroral features: thin, short-lived green stripes and a “picket fence” near the poleward edge of the auroral oval. Using ground cameras and satellites, we found that the stripes sometimes appeared at widely separated longitudes at the same time and often tracked the motion of nearby red auroras. Some stripes were aligned with the magnetic field, while others were not, implying that multiple local processes contribute to their generation.
Gaël Cessateur, Keisuke Hosokawa, Hervé Lamy, Sota Nanjo, Mathieu Barthelemy, Magnar G. Johnsen, and Romain Maggiolo
EGUsphere, https://doi.org/10.5194/egusphere-2026-385, https://doi.org/10.5194/egusphere-2026-385, 2026
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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The Auroral Spectrograph in Skibotn has been measuring auroral light spectra since October 2023. We estimate the energy of electrons producing diffuse auroras from red oxygen and blue nitrogen emissions. Our statistical analysis shows that electron energy increases toward the morning sector, confirming previous studies: electron scattering by chorus waves can populate the loss cone and lead to precipitation, while changes in resonance conditions toward dawn favor harder electrons
Rowan Dayton-Oxland, Fiona Ball, Daniel Whiter, Srimoyee Samaddar, Noora Partamies, Mathieu Barthelemy, Katie Herlingshaw, and Eero Karvinen
EGUsphere, https://doi.org/10.5194/egusphere-2025-5317, https://doi.org/10.5194/egusphere-2025-5317, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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GHOST is a pale mauve aurora, usually seen near noon in Svalbard during polar night, emitting a continuum spectrum across the visible range. Our fitting of high-resolution spectra shows that GHOST emission is best explained by extremely hot nitrogen and oxygen molecules, not by the more scarce nitrous oxide which is usually assumed. We propose that strong ionospheric flows, daylight, and incoming solar‑wind particles combine to heat the upper atmosphere, priming it to produce GHOST aurora.
Maxime Grandin, Liisa Juusola, Noora Partamies, Emma Bruus, Joona Rautiainen, Donna Lach, Jia Jia, Max van de Kamp, Eero Karvinen, Kirsti Kauristie, and Theresa Hoppe
EGUsphere, https://doi.org/10.5194/egusphere-2025-5374, https://doi.org/10.5194/egusphere-2025-5374, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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Dune aurora is an intriguing phenomenon recently discovered thanks to citizen science. It is a dim, diffuse auroral form exhibiting wave-like stripes of brighter emission. We carry out the first statistical study of dune aurora, using 289 observation reports submitted to the Skywarden database by citizen scientists from Europe, North America, and Oceania. We find that dunes are an evening phenomenon, most often reported in March and October and associated with currents in the auroral atmosphere.
Rumi Nakamura, Thierry Dudok de Wit, Geraint H. Jones, Matt G. G. T. Taylor, Nicolas André, Charlotte Goetz, Lina Z. Hadid, Laura A. Hayes, Heli Hietala, Caitríona M. Jackman, Larry Kepko, Aurélie Marchaudon, Adam Masters, Mathew Owens, Noora Partamies, Stefaan Poedts, Jonathan Rae, Yuri Shprits, Manuela Temmer, Daniel Verscharen, and Robert F. Wimmer-Schweingruber
Ann. Geophys., 43, 855–879, https://doi.org/10.5194/angeo-43-855-2025, https://doi.org/10.5194/angeo-43-855-2025, 2025
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Heliophysics spans a wide range of disciplines covering the study of the Sun and the different Solar System bodies, such as Earth and other planets, moons, comets, and asteroids, and their interactions with the Sun, focusing on plasma and atmospheric processes. A grass-roots effort has been recently started toward establishing a European Heliophysics Community (https://www.heliophysics.eu/). This white paper outlines the motivation, priorities, and a future vision of Heliophysics in Europe.
Liisa Juusola, Ilkka Virtanen, Spencer Mark Hatch, Heikki Vanhamäki, Maxime Grandin, Noora Partamies, Urs Ganse, Ilja Honkonen, Abiyot Workayehu, Antti Kero, and Minna Palmroth
Ann. Geophys., 43, 755–781, https://doi.org/10.5194/angeo-43-755-2025, https://doi.org/10.5194/angeo-43-755-2025, 2025
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Key properties of the ionospheric electrodynamics are electric fields, currents, and conductances. They provide a window to the vast and distant near-Earth space, cause Joule heating that affect satellite orbits, and drive geomagnetically induced currents (GICs) in technological conductor networks. We have developed a new method for solving the key properties of ionospheric electrodynamics from ground-based magnetic field observations.
Abiyot Workayehu, Minna Palmroth, Maxime Grandin, Liisa Juusola, Markku Alho, Ivan Zaitsev, Venla Koikkalainen, Konstantinos Horaites, Yann Pfau-Kempf, Urs Ganse, Markus Battarbee, and Jonas Suni
Ann. Geophys., 43, 723–737, https://doi.org/10.5194/angeo-43-723-2025, https://doi.org/10.5194/angeo-43-723-2025, 2025
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This study investigates the ionospheric signatures of a Bursty Bulk Flow in Earth’s magnetotail using a global 6D hybrid-Vlasov simulation coupled with an ionospheric model. The results show that a reconnection-driven Bursty Bulk Flow generates vortices that produce field-aligned currents, which map to the ionosphere with a distinct east–west orientation and exhibit a characteristic westward drift. Variations in ionospheric observables are identified as clear signatures of this flow.
Ilkka I. Virtanen, Ayanew Nigusie, Antti Kero, Neethal Thomas, and Juhana Lankinen
Atmos. Meas. Tech., 18, 5895–5917, https://doi.org/10.5194/amt-18-5895-2025, https://doi.org/10.5194/amt-18-5895-2025, 2025
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EISCAT3D is an ionospheric radar currently under construction in Northern Fenno-Scandinavia. The radar will make 3D measurements of the ionosphere at 50–1000 km altitudes. We show that the so-called multipurpose radar modulations and optimal data analysis can improve the time resolution of the measurements by more than an order of magnitude, and they enable one to measure ion-neutral collision frequencies, which are proportional to neutral particle density, in the lower ionosphere.
Spencer Mark Hatch, Ilkka Virtanen, Karl Magnus Laundal, Habtamu Wubie Tesfaw, Juha Vierinen, Devin Ray Huyghebaert, Andres Spicher, and Jens Christian Hessen
Ann. Geophys., 43, 633–649, https://doi.org/10.5194/angeo-43-633-2025, https://doi.org/10.5194/angeo-43-633-2025, 2025
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This study addresses the design of next-generation incoherent scatter radar experiments used to study the ionosphere, particularly with systems that have multiple sites. We have developed a method to estimate uncertainties of measurements of plasma density, temperature, and ion drift. Our method is open-source, and helps to optimize radar configurations and assess the effectiveness of an experiment. This method ultimately serves to enhance our understanding of Earth's space environment.
Yann Pfau-Kempf, Konstantinos Papadakis, Markku Alho, Markus Battarbee, Giulia Cozzani, Lauri Pänkäläinen, Urs Ganse, Fasil Kebede, Jonas Suni, Konstantinos Horaites, Maxime Grandin, and Minna Palmroth
Ann. Geophys., 43, 469–488, https://doi.org/10.5194/angeo-43-469-2025, https://doi.org/10.5194/angeo-43-469-2025, 2025
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Flux ropes are peculiar structures of twisted magnetic field occurring in many regions of space, near Earth and other planets, at the Sun, and in astrophysical objects. We developed a new way of detecting flux ropes in large supercomputer simulations of near-Earth space, and we use it to follow the evolution of flux ropes for long distances past the Earth in the flow direction. This will be useful in future studies as these flux ropes are involved in the transport of matter and energy in space.
Venla Koikkalainen, Maxime Grandin, Emilia Kilpua, Abiyot Workayehu, Ivan Zaitsev, Liisa Juusola, Shi Tao, Markku Alho, Lauri Pänkäläinen, Giulia Cozzani, Konstantinos Horaites, Jonas Suni, Yann Pfau-Kempf, Urs Ganse, and Minna Palmroth
EGUsphere, https://doi.org/10.5194/egusphere-2025-2265, https://doi.org/10.5194/egusphere-2025-2265, 2025
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We use a numerical simulation to study phenomena that occur between the Earth’s dipolar magnetic field and the nightside of near-Earth space. We observe the formation of large-scale vortex flows with scales of several Earth radii. On the ionospheric grid of the simulation we find that the field-aligned currents formed in the simulation reflect the vortex flow in the transition region. The main finding is that the vortex flow is a result of a combination of flow dynamics and a plasma instability.
Oliver Stalder, Björn Gustavsson, and Ilkka Virtanen
EGUsphere, https://doi.org/10.5194/egusphere-2025-2340, https://doi.org/10.5194/egusphere-2025-2340, 2025
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The rapid changes in ion composition during auroral are dynamically modeled by integrating the coupled continuity equations for 15 ionospheric species. The effect of the ionospheric variation on the inversion of ISR electron density profiles to differential energy spectra of precipitating electrons is studied. A systematic overestimation at high electron energies can be removed using a dynamic model. Comparisons are made with static and steady-state ionospheric models.
Tuomas Häkkilä, Maxime Grandin, Markus Battarbee, Monika E. Szeląg, Markku Alho, Leo Kotipalo, Niilo Kalakoski, Pekka T. Verronen, and Minna Palmroth
Ann. Geophys., 43, 217–240, https://doi.org/10.5194/angeo-43-217-2025, https://doi.org/10.5194/angeo-43-217-2025, 2025
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We study the atmospheric impact of auroral electron precipitation through the novel combination of both magnetospheric modelling and atmospheric modelling. We first simulate fluxes of auroral electrons and then use these fluxes to model their atmospheric impact. We find an increase of more than 200 % in thermospheric odd nitrogen and a corresponding decrease in stratospheric ozone of around 0.8 %. The produced auroral electron precipitation is realistic and shows potential for future studies.
Urs Ganse, Yann Pfau-Kempf, Hongyang Zhou, Liisa Juusola, Abiyot Workayehu, Fasil Kebede, Konstantinos Papadakis, Maxime Grandin, Markku Alho, Markus Battarbee, Maxime Dubart, Leo Kotipalo, Arnaud Lalagüe, Jonas Suni, Konstantinos Horaites, and Minna Palmroth
Geosci. Model Dev., 18, 511–527, https://doi.org/10.5194/gmd-18-511-2025, https://doi.org/10.5194/gmd-18-511-2025, 2025
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Vlasiator is a kinetic space plasma model that simulates the behavior of plasma, solar wind and magnetic fields in near-Earth space. So far, these simulations have been run without any interaction with the ionosphere, the uppermost layer of Earth's atmosphere. In this paper, we present the new methods that add an ionospheric electrodynamics model to Vlasiator, coupling it with the existing methods and presenting new simulation results of how space plasma and Earth's ionosphere interact.
Devin Huyghebaert, Björn Gustavsson, Juha Vierinen, Andreas Kvammen, Matthew Zettergren, John Swoboda, Ilkka Virtanen, Spencer M. Hatch, and Karl M. Laundal
Ann. Geophys., 43, 99–113, https://doi.org/10.5194/angeo-43-99-2025, https://doi.org/10.5194/angeo-43-99-2025, 2025
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The EISCAT_3D radar is a new ionospheric radar under construction in the Fennoscandia region. The radar will make measurements of plasma characteristics at altitudes above approximately 60 km. The capability of the system to make these measurements at spatial scales of less than 100 m using multiple digitised signals from each of the radar antenna panels is highlighted. There are many ionospheric small-scale processes that will be further resolved using the techniques discussed here.
Maxime Grandin, Emma Bruus, Vincent E. Ledvina, Noora Partamies, Mathieu Barthelemy, Carlos Martinis, Rowan Dayton-Oxland, Bea Gallardo-Lacourt, Yukitoshi Nishimura, Katie Herlingshaw, Neethal Thomas, Eero Karvinen, Donna Lach, Marjan Spijkers, and Calle Bergstrand
Geosci. Commun., 7, 297–316, https://doi.org/10.5194/gc-7-297-2024, https://doi.org/10.5194/gc-7-297-2024, 2024
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We carried out a citizen science study of aurora sightings and technological disruptions experienced during the extreme geomagnetic storm of 10 May 2024. We collected reports from 696 observers from over 30 countries via an online survey, supplemented with observations logged in the Skywarden database. We found that the aurora was seen from exceptionally low latitudes and had very bright red and pink hues, suggesting that high fluxes of low-energy electrons from space entered the atmosphere.
Rowan Dayton-Oxland, Daniel K. Whiter, Hyomin Kim, and Betty Lanchester
EGUsphere, https://doi.org/10.22541/essoar.172641540.02035523/v1, https://doi.org/10.22541/essoar.172641540.02035523/v1, 2024
Preprint archived
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It is typically thought that the protons which precipitate down from space to cause proton aurora are accelerated by a type of plasma wave called an EMIC wave. In this study we use ground-based observations of proton aurora and Pc1 waves (the ground signature of EMIC waves) to test whether this mechanism occurs in the high Arctic over Svalbard, on the Earth's day side. We did not find any link between the proton aurora and Pc1 pulsations, contrary to our expectations.
Maxime Grandin, Noora Partamies, and Ilkka I. Virtanen
Ann. Geophys., 42, 355–369, https://doi.org/10.5194/angeo-42-355-2024, https://doi.org/10.5194/angeo-42-355-2024, 2024
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Auroral displays typically take place at high latitudes, but the exact latitude where the auroral breakup occurs can vary. In this study, we compare the characteristics of the fluxes of precipitating electrons from space during auroral breakups occurring above Tromsø (central part of the auroral zone) and above Svalbard (poleward boundary of the auroral zone). We find that electrons responsible for the aurora above Tromsø carry more energy than those precipitating above Svalbard.
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.
Peter Dalin, Urban Brändström, Johan Kero, Peter Voelger, Takanori Nishiyama, Trond Trondsen, Devin Wyatt, Craig Unick, Vladimir Perminov, Nikolay Pertsev, and Jonas Hedin
Atmos. Meas. Tech., 17, 1561–1576, https://doi.org/10.5194/amt-17-1561-2024, https://doi.org/10.5194/amt-17-1561-2024, 2024
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A novel infrared imaging instrument (OH imager) was put into operation in November 2022 at the Swedish Institute of Space Physics in Kiruna (Sweden). The OH imager is dedicated to the study of nightglow emissions coming from the hydroxyl (OH) and molecular oxygen (O2) layers in the mesopause (80–100 km). Based on a brightness ratio of two OH emission lines, the neutral temperature is estimated at around 87 km. The average daily winter temperature for the period January–April 2023 is 203±10 K.
Anton Goertz, Noora Partamies, Daniel Whiter, and Lisa Baddeley
Ann. Geophys., 41, 115–128, https://doi.org/10.5194/angeo-41-115-2023, https://doi.org/10.5194/angeo-41-115-2023, 2023
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Poleward moving auroral forms (PMAFs) are specific types of aurora believed to be the signature of the connection of Earth's magnetic field to that of the sun. In this paper, we discuss the evolution of PMAFs with regard to their auroral morphology as observed in all-sky camera images. We interpret different aspects of this evolution in terms of the connection dynamics between the magnetic fields of Earth and the sun. This sheds more light on the magnetic interaction between the sun and Earth.
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.
Konstantinos Papadakis, Yann Pfau-Kempf, Urs Ganse, Markus Battarbee, Markku Alho, Maxime Grandin, Maxime Dubart, Lucile Turc, Hongyang Zhou, Konstantinos Horaites, Ivan Zaitsev, Giulia Cozzani, Maarja Bussov, Evgeny Gordeev, Fasil Tesema, Harriet George, Jonas Suni, Vertti Tarvus, and Minna Palmroth
Geosci. Model Dev., 15, 7903–7912, https://doi.org/10.5194/gmd-15-7903-2022, https://doi.org/10.5194/gmd-15-7903-2022, 2022
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Vlasiator is a plasma simulation code that simulates the entire near-Earth space at a global scale. As 6D simulations require enormous amounts of computational resources, Vlasiator uses adaptive mesh refinement (AMR) to lighten the computational burden. However, due to Vlasiator’s grid topology, AMR simulations suffer from grid aliasing artifacts that affect the global results. In this work, we present and evaluate the performance of a mechanism for alleviating those artifacts.
Noora Partamies, Daniel Whiter, Kirsti Kauristie, and Stefano Massetti
Ann. Geophys., 40, 605–618, https://doi.org/10.5194/angeo-40-605-2022, https://doi.org/10.5194/angeo-40-605-2022, 2022
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We investigate the local time behaviour of auroral structures and emission height. Data are collected from the Fennoscandian Lapland and Svalbard latitutes from 7 identical auroral all-sky cameras over about 1 solar cycle. The typical peak emission height of the green aurora varies from 110 km on the nightside to about 118 km in the morning over Lapland but stays systematically higher over Svalbard. During fast solar wind, nightside emission heights are 5 km lower than during slow solar wind.
Snizhana Ross, Arttu Arjas, Ilkka I. Virtanen, Mikko J. Sillanpää, Lassi Roininen, and Andreas Hauptmann
Atmos. Meas. Tech., 15, 3843–3857, https://doi.org/10.5194/amt-15-3843-2022, https://doi.org/10.5194/amt-15-3843-2022, 2022
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Radar measurements of thermal fluctuations in the Earth's ionosphere produce weak signals, and tuning to specific altitudes results in suboptimal resolution for other regions, making an accurate analysis of these changes difficult. A novel approach to improve the resolution and remove measurement noise is considered. The method can capture variable characteristics, making it ideal for the study of a large range of data. Synthetically generated examples and two measured datasets were considered.
Fasil Tesema, Noora Partamies, Daniel K. Whiter, and Yasunobu Ogawa
Ann. Geophys., 40, 1–10, https://doi.org/10.5194/angeo-40-1-2022, https://doi.org/10.5194/angeo-40-1-2022, 2022
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In this study, we present the comparison between an auroral model and EISCAT radar electron densities during pulsating aurorae. We test whether an overpassing satellite measurement of the average energy spectrum is a reasonable estimate for pulsating aurora electron precipitation. When patchy pulsating aurora is dominant in the morning sector, the overpass-averaged spectrum is found to be a reasonable estimate – but not when there is a mix of pulsating aurora types in the post-midnight sector.
Daniel K. Whiter, Hanna Sundberg, Betty S. Lanchester, Joshua Dreyer, Noora Partamies, Nickolay Ivchenko, Marco Zaccaria Di Fraia, Rosie Oliver, Amanda Serpell-Stevens, Tiffany Shaw-Diaz, and Thomas Braunersreuther
Ann. Geophys., 39, 975–989, https://doi.org/10.5194/angeo-39-975-2021, https://doi.org/10.5194/angeo-39-975-2021, 2021
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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.
Vertti Tarvus, Lucile Turc, Markus Battarbee, Jonas Suni, Xóchitl Blanco-Cano, Urs Ganse, Yann Pfau-Kempf, Markku Alho, Maxime Dubart, Maxime Grandin, Andreas Johlander, Konstantinos Papadakis, and Minna Palmroth
Ann. Geophys., 39, 911–928, https://doi.org/10.5194/angeo-39-911-2021, https://doi.org/10.5194/angeo-39-911-2021, 2021
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We use simulations of Earth's magnetosphere and study the formation of transient wave structures in the region where the solar wind first interacts with the magnetosphere. These transients move earthward and play a part in the solar wind–magnetosphere interaction. We show that the transients are a common feature and their properties are altered as they move earthward, including an increase in temperature, decrease in solar wind speed and an alteration in their propagation properties.
Pekka T. Verronen, Antti Kero, Noora Partamies, Monika E. Szeląg, Shin-Ichiro Oyama, Yoshizumi Miyoshi, and Esa Turunen
Ann. Geophys., 39, 883–897, https://doi.org/10.5194/angeo-39-883-2021, https://doi.org/10.5194/angeo-39-883-2021, 2021
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This paper is the first to simulate and analyse the pulsating aurorae impact on middle atmosphere on monthly/seasonal timescales. We find that pulsating aurorae have the potential to make a considerable contribution to the total energetic particle forcing and increase the impact on upper stratospheric odd nitrogen and ozone in the polar regions. Thus, it should be considered in atmospheric and climate simulations.
Andrei Runov, Maxime Grandin, Minna Palmroth, Markus Battarbee, Urs Ganse, Heli Hietala, Sanni Hoilijoki, Emilia Kilpua, Yann Pfau-Kempf, Sergio Toledo-Redondo, Lucile Turc, and Drew Turner
Ann. Geophys., 39, 599–612, https://doi.org/10.5194/angeo-39-599-2021, https://doi.org/10.5194/angeo-39-599-2021, 2021
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In collisionless systems like space plasma, particle velocity distributions contain fingerprints of ongoing physical processes. However, it is challenging to decode this information from observations. We used hybrid-Vlasov simulations to obtain ion velocity distribution functions at different locations and at different stages of the Earth's magnetosphere dynamics. The obtained distributions provide valuable examples that may be directly compared with observations by satellites in space.
Emranul Sarkar, Alexander Kozlovsky, Thomas Ulich, Ilkka Virtanen, Mark Lester, and Bernd Kaifler
Atmos. Meas. Tech., 14, 4157–4169, https://doi.org/10.5194/amt-14-4157-2021, https://doi.org/10.5194/amt-14-4157-2021, 2021
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The biasing effect in meteor radar temperature has been a pressing issue for the last 2 decades. This paper has addressed the underlying reasons for such a biasing effect on both theoretical and experimental grounds. An improved statistical method has been developed which allows atmospheric temperatures at around 90 km to be measured with meteor radar in an independent way such that any subsequent bias correction or calibration is no longer required.
Haimeng Li, Wen Li, Qianli Ma, Yukitoshi Nishimura, Zhigang Yuan, Alex J. Boyd, Xiaochen Shen, Rongxin Tang, and Xiaohua Deng
Ann. Geophys., 39, 461–470, https://doi.org/10.5194/angeo-39-461-2021, https://doi.org/10.5194/angeo-39-461-2021, 2021
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We report an event where hiss wave intensity decreased, associated with the enhanced convection and a substorm. We suggest that the enhanced magnetospheric electric field causes the outward and sunward motion of energetic electrons. This leads to the decrease of energetic electron fluxes on the duskside, which provide free energy for hiss amplification. The study reveals the important role of magnetospheric electric field in the variation of the energetic electron flux and hiss wave intensity.
Minna Palmroth, Savvas Raptis, Jonas Suni, Tomas Karlsson, Lucile Turc, Andreas Johlander, Urs Ganse, Yann Pfau-Kempf, Xochitl Blanco-Cano, Mojtaba Akhavan-Tafti, Markus Battarbee, Maxime Dubart, Maxime Grandin, Vertti Tarvus, and Adnane Osmane
Ann. Geophys., 39, 289–308, https://doi.org/10.5194/angeo-39-289-2021, https://doi.org/10.5194/angeo-39-289-2021, 2021
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Magnetosheath jets are high-velocity features within the Earth's turbulent magnetosheath, separating the Earth's magnetic domain from the solar wind. The characteristics of the jets are difficult to assess statistically as a function of their lifetime because normally spacecraft observe them only at one position within the magnetosheath. This study first confirms the accuracy of the model used, Vlasiator, by comparing it to MMS spacecraft, and then carries out the first jet lifetime statistics.
Joshua Dreyer, Noora Partamies, Daniel Whiter, Pål G. Ellingsen, Lisa Baddeley, and Stephan C. Buchert
Ann. Geophys., 39, 277–288, https://doi.org/10.5194/angeo-39-277-2021, https://doi.org/10.5194/angeo-39-277-2021, 2021
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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,
aurora-like). We analyse data from multiple instruments located near Longyearbyen to derive their main characteristics. They seem to occur as two types in a narrow altitude region (individually or in regularly spaced groups).
Minna Palmroth, Maxime Grandin, Theodoros Sarris, Eelco Doornbos, Stelios Tourgaidis, Anita Aikio, Stephan Buchert, Mark A. Clilverd, Iannis Dandouras, Roderick Heelis, Alex Hoffmann, Nickolay Ivchenko, Guram Kervalishvili, David J. Knudsen, Anna Kotova, Han-Li Liu, David M. Malaspina, Günther March, Aurélie Marchaudon, Octav Marghitu, Tomoko Matsuo, Wojciech J. Miloch, Therese Moretto-Jørgensen, Dimitris Mpaloukidis, Nils Olsen, Konstantinos Papadakis, Robert Pfaff, Panagiotis Pirnaris, Christian Siemes, Claudia Stolle, Jonas Suni, Jose van den IJssel, Pekka T. Verronen, Pieter Visser, and Masatoshi Yamauchi
Ann. Geophys., 39, 189–237, https://doi.org/10.5194/angeo-39-189-2021, https://doi.org/10.5194/angeo-39-189-2021, 2021
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This is a review paper that summarises the current understanding of the lower thermosphere–ionosphere (LTI) in terms of measurements and modelling. The LTI is the transition region between space and the atmosphere and as such of tremendous importance to both the domains of space and atmosphere. The paper also serves as the background for European Space Agency Earth Explorer 10 candidate mission Daedalus.
Emma Bland, Fasil Tesema, and Noora Partamies
Ann. Geophys., 39, 135–149, https://doi.org/10.5194/angeo-39-135-2021, https://doi.org/10.5194/angeo-39-135-2021, 2021
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A total of 10 Super Dual Auroral Radar Network radars were used to estimate the horizontal area over which energetic electrons impact the atmosphere at 70–100 km altitude during pulsating aurorae (PsAs). The impact area varies significantly from event to event. Approximately one-third extend over 12° of magnetic latitude, while others are highly localised. Our results could be used to improve the forcing used in atmospheric/climate models to properly capture the energy contribution from PsAs.
Cited articles
Archer, W. E., Gallardo-Lacourt, B., Perry, G. W., St.-Maurice, J. P., Buchert, S. C., and Donovan, E.: Steve: The Optical Signature of Intense Subauroral Ion Drifts, Geophys. Res. Lett., 46, 6279–6286, https://doi.org/10.1029/2019GL082687, 2019a. a, b, c
Archer, W. E., Maurice, J.-P. S., Gallardo‐Lacourt, B., Perry, G. W., Cully, C. M., Donovan, E., Gillies, D. M., Downie, R., Smith, J., and Eurich, D.: The Vertical Distribution of the Optical Emissions of a Steve and Picket Fence Event, Geophys. Res. Lett., 46, 10719–10725, https://doi.org/10.1029/2019GL084473, 2019b. a
Aruliah, A., Förster, M., Hood, R., McWhirter, I., and Doornbos, E.: Comparing high-latitude thermospheric winds from Fabry–Perot interferometer (FPI) and challenging mini-satellite payload (CHAMP) accelerometer measurements, Ann. Geophys., 37, 1095–1120, https://doi.org/10.5194/angeo-37-1095-2019, 2019. a
Aruliah, A. L. and Griffin, E.: Evidence of meso-scale structure in the high-latitude thermosphere, Ann. Geophys., 19, 37–46, https://doi.org/10.5194/angeo-19-37-2001, 2001. a
Aruliah, A. L., Griffin, E. M., Yiu, H.-C. I., McWhirter, I., and Charalambous, A.: SCANDI – an all-sky Doppler imager for studies of thermospheric spatial structure, Ann. Geophys., 28, 549–567, https://doi.org/10.5194/angeo-28-549-2010, 2010. a
Chakrabarti, S., Pallamraju, D., Baumgardner, J., and Vaillancourt, J.: HiTIES: A High Throughput Imaging Echelle Spectrogragh for ground-based visible airglow and auroral studies, J. Geophys. Res.-Space Phys., 106, 30337–30348, https://doi.org/10.1029/2001JA001105, 2001. a
Chamberlain, J. W.: Physics of the Aurora and Airglow, Academic Press, ISBN 9781483222530 (e-Book), 1961. a
Chamberlain, J. W. and Oliver, N. J.: Atomic and molecular transitions in auroral spectra, J. Geophys. Res., 58, 457–472, https://doi.org/10.1029/JZ058i004p00457, 1953. a
Cornelius, J. R. and Mazzella, Andrew J., J.: The topside ionospheric plasma monitor (SSIES, SSIES-2 and SSIES-3) on the spacecraft of the Defense Meteorological Satellite Program (DMSP), user's guide. Volume 2: Programmer's guide for software at AFSFC, Scientific Report No. 4 RDP, Inc., Waltham, MA, 1994. a
Dreyer, J., Partamies, N., Whiter, D., Ellingsen, P. G., Baddeley, L., and Buchert, S. C.: Characteristics of fragmented aurora-like emissions (FAEs) observed on Svalbard, Ann. Geophys., 39, 277–288, https://doi.org/10.5194/angeo-39-277-2021, 2021. a, b
Gallardo-Lacourt, B., Nishimura, Y., Donovan, E., Gillies, D. M., Perry, G. W., Archer, W. E., Nava, O. A., and Spanswick, E. L.: A Statistical Analysis of STEVE, J. Geophys. Res.-Space Phys., 123, 9893–9905, https://doi.org/10.1029/2018JA025368, 2018a. a, b, c
Gallardo-Lacourt, B., Liang, J., Nishimura, Y., and Donovan, E.: On the Origin of STEVE: Particle Precipitation or Ionospheric Skyglow?, Geophys. Res. Lett., 45, 7968–7973, https://doi.org/10.1029/2018GL078509, 2018b. a
Gallardo-Lacourt, B., Nishimura, Y., Kepko, L., Spanswick, E. L., Gillies, D. M., Knudsen, D. J., Burchill, J. K., Skone, S. H., Pinto, V. A., Chaddock, D., Kuzub, J., and Donovan, E. F.: Unexpected STEVE Observations at High Latitude During Quiet Geomagnetic Conditions, Geophys. Res. Lett., 51, e2024GL110568, https://doi.org/10.1029/2024GL110568, 2024. a
Gillies, D. M., Donovan, E., Hampton, D., Liang, J., Connors, M., Nishimura, Y., Gallardo‐Lacourt, B., and Spanswick, E.: First Observations From the TREx Spectrograph: The Optical Spectrum of STEVE and the Picket Fence Phenomena, Geophys. Res. Lett., 46, 7207–7213, https://doi.org/10.1029/2019GL083272, 2019. a
Gillies, D. M., Liang, J., Gallardo-Lacourt, B., and Donovan, E.: New Insight Into the Transition From a SAR Arc to STEVE, Geophys. Res. Lett., 50, e2022GL101205, https://doi.org/10.1029/2022GL101205, 2023. a
Harding, B. J., Mende, S. B., Triplett, C. C., and Wu, Y.-J. J.: A Mechanism for the STEVE Continuum Emission, Geophys. Res. Lett., 47, e2020GL087102, https://doi.org/10.1029/2020GL087102, 2020. a, b, c
Herlingshaw, K., Partamies, N., van Hazendonk, C. M., Syrjäsuo, M., Baddeley, L., Johnsen, M., Eriksen, N. K., McWhirter, I., Aruliah, A. L., Engebretson, M. J., Oksavik, K., Sigernes, F., Lorentzen, D. A., Nishiyama, T., Cooper, M. B., Meriwether, J. W., Haaland, S., and Whiter, D. K.: Science Highlights from the Kjell Henriksen Observatory on Svalbard, Arct. Sci., 11, 1–25, https://doi.org/10.1139/as-2024-0009, 2024. a
Innis, J., Dyson, P., and Greet, P.: Further observations of the thermospheric vertical wind at the auroral oval/polar cap boundary, J. Atmos. Solar-Terr. Phy., 59, 2009–2022, https://doi.org/10.1016/S1364-6826(97)00034-5, 1997. a
Kataoka, R., Miyoshi, Y., Shiokawa, K., Nishitani, N., Keika, K., Amano, T., and Seki, K.: Magnetic Storm-Time Red Aurora as Seen From Hokkaido, Japan on 1 December 2023 Associated With High-Density Solar Wind, Geophys. Res. Lett., 51, e2024GL108778, https://doi.org/10.1029/2024GL108778, 2024. a
Liang, J., Donovan, E., Connors, M., Gillies, D., St-Maurice, J. P., Jackel, B., Gallardo-Lacourt, B., Spanswick, E., and Chu, X.: Optical Spectra and Emission Altitudes of Double-Layer STEVE: A Case Study, Geophys. Res. Lett., 46, 13630–13639, https://doi.org/10.1029/2019GL085639, 2019. a
MacDonald, E. A., Donovan, E., Nishimura, Y., Case, N. A., Gillies, D. M., Gallardo-Lacourt, B., Archer, W. E., Spanswick, E. L., Bourassa, N., Connors, M., Heavner, M., Jackel, B., Kosar, B., Knudsen, D. J., Ratzlaff, C., and Schofield, I.: New science in plain sight: Citizen scientists lead to the discovery of optical structure in the upper atmosphere, Sci. Adv., 4, eaaq0030, https://doi.org/10.1126/sciadv.aaq0030, 2018. a, b
Martinis, C., Griffin, I., Gallardo-Lacourt, B., Wroten, J., Nishimura, Y., Baumgardner, J., and Knudsen, D. J.: Rainbow of the Night: First Direct Observation of a SAR Arc Evolving Into STEVE, Geophys. Res. Lett., 49, e2022GL098511, https://doi.org/10.1029/2022GL098511, 2022. a
Meinel, A. B.: Origin of the Continuum in the Night-Sky Spectrum, Astrophys. J., 118, 200, https://doi.org/10.1086/145742, 1953. a
Mende, S. B. and Turner, C.: Color Ratios of Subauroral (STEVE) Arcs, J. Geophys. Res., 124, 5945–5955, https://doi.org/10.1029/2019JA026851, 2019. a
Mishin, E. and Streltsov, A.: STEVE and the Picket Fence: Evidence of Feedback-Unstable Magnetosphere-Ionosphere Interaction, Geophys. Res. Lett., 46, 14247–14255, https://doi.org/10.1029/2019GL085446, 2019. a
Nanjo, S., Hofstra, G., and Shiokawa, K. E. A.: Post-midnight purple arc and patches appeared on the high latitude part of the auroral oval: Dawnside counterpart of STEVE?, Earth Planet. Space, 76, e2020GL087102, https://doi.org/10.1186/s40623-024-01995-9, 2024. a, b, c
Nishimura, Y., Gallardo-Lacourt, B., Zou, Y., Mishin, E., Knudsen, D. J., Donovan, E. F., Angelopoulos, V., and Raybell, R.: Magnetospheric Signatures of STEVE: Implications for the Magnetospheric Energy Source and Interhemispheric Conjugacy, Geophys. Res. Lett., 46, 5637–5644, https://doi.org/10.1029/2019GL082460, 2019. a, b
Nishimura, Y., Gallardo-Lacourt, B., Donovan, E. F., Angelopoulos, V., and Nishitani, N.: Auroral and magnetotail dynamics during quiet-time STEVE and SAID, J. Geophys. Res.-Space Phys., 129, e2024JA032941, https://doi.org/10.1029/2024JA032941, 2024. a
Nishiyama, T., Kagitani, M., Furutachi, S., Iwasa, Y., Ogawa, Y., Tsuda, T. T., Dalin, P., Tsuchiya, F., Nozawa, S., and Sigernes, F.: The first simultaneous spectroscopic and monochromatic imaging observations of short-wavelength infrared aurora of Meinel (0,0) band at 1.1 m with incoherent scatter radar, Earth Planet. Space, 76, 30, https://doi.org/10.1186/s40623-024-01969-x, 2024. a, b
Noll, S., Plane, J. M. C., Feng, W., Kalogerakis, K. S., Kausch, W., Schmidt, C., Bittner, M., and Kimeswenger, S.: Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800 nm: evidence for HO2 emission in the near-infrared, Atmos. Chem. Phys., 24, 1143–1176, https://doi.org/10.5194/acp-24-1143-2024, 2024. a
Papitashvili, N. E. and King, J. H.: OMNI 5-min Data Set, NASA Space Physics Data Facility [data set], https://doi.org/10.48322/gbpg-5r77, 2020. a
Papitashvili, N. E. and King, J. H.: OMNI 1-min Data, NASA Space Physics Data Facility [data set], https://doi.org/10.48322/45bb-8792 (last access: 12 June 2025), 2020. a
Partamies, N.: First observations of continuum emission in dayside aurora, Zenodo [data set], https://doi.org/10.5281/zenodo.13960606, 2024. a, b
Reimer, A., amisr-user, and Guenzkofer, F.: amisr/flipchem: v2021.2.2 Bugfix Release (v2021.2.2), Zenodo [code], https://doi.org/10.5281/zenodo.5719844, 2021. a
Rideout, W. and Cariglia, K.: CEDAR Madrigal Database, CEDAR [data set], https://cedar.openmadrigal.org, last access: 12 June 2025. a
Shinagawa, H., Oyama, S., Nozawa, S., Buchert, S., Fujii, R., and Ishii, M.: Thermospheric and ionospheric dynamics in the auroral region, Adv. Space Res., 31, 951–956, https://doi.org/10.1016/S0273-1177(02)00792-5, 2003. a
Shiokawa, K., Otsuka, Y., and Connors, M.: Statistical Study of Auroral/Resonant-Scattering 427.8-nm Emission Observed at Subauroral Latitudes Over 14 Years, J. Geophys. Res.-Space Phys., 124, 9293–9301, https://doi.org/10.1029/2019JA026704, 2019. a
Syrjäsuo, M.: Software for Meridian Imaging Svalbard Spectrograph (MISS), Github [code], https://github.com/UNISvalbard/KHO-MISS, last access: 2 July 2025a. a
Syrjäsuo, M.: Star calibration of all-sky images, Github [code], https://github.com/UNISvalbard/KHO-starcalibration, last access: 2 July 2025b. a
Spanswick, E., Liang, J., Houghton, J., Donovan, E., Gallardo-Lacourt, B., Nishimura, Y., Chaddock, D., Keenan, C., Rosehart, J., and Gillies, D.: Association of structured continuum emission with dynamic aurora, Nat. Commun., 15, 10802, https://doi.org/10.1038/s41467-024-55081-5, 2024. a, b, c
Virtanen, I. I.: Bayesian Filtering Module (v0.2), Zenodo [code], https://doi.org/10.5281/zenodo.10656396, 2024. a
Virtanen, I. I., Tesfaw, H. W., Roininen, L., Lasanen, S., and Aikio, A.: Bayesian Filtering in Incoherent Scatter Plasma Parameter Fits, J. Geophys. Res.-Space Phys., 126, e2020JA028700, https://doi.org/10.1029/2020JA028700, 2021. a
Virtanen, I. I., Tesfaw, H. W., Aikio, A. T., Varney, R., Kero, A., and Thomas, N.: F1 Region Ion Composition in Svalbard During the International Polar Year 2007–2008, J. Geophys. Res.-Space Phys., 129, e2023JA032202, https://doi.org/10.1029/2023JA032202, 2024. a, b
Wannberg, G., Wolf, I., Vanhainen, L.-G., Koskenniemi, K., Röttger, J., Postila, M., Markkanen, J., Jacobsen, R., Stenberg, A., Larsen, R., Eliassen, S., Heck, S., and Huuskonen, A.: The EISCAT Svalbard radar: A case study in modern incoherent scatter radar system design, Radio Sci., 32, 2283–2307, https://doi.org/10.1029/97RS01803, 1997. a
Editor-in-chief
The manuscript reports the first observations of continuum emission at the poleward boundary of the dayside auroral oval. The unique measurements show that a number of different emission lines and bands contribute to the broadband continuum emission. Even emission structures in the near and far infrared were observed, suggesting that multiple emitting species are responsible for the observed spectral enhancements. The authors suggest that the interplay of different heating mechanisms may be an important factor in the generation of high-latitude continuum emissions.
The manuscript reports the first observations of continuum emission at the poleward boundary of...
Short summary
We studied the first broad band emissions, called continuum, in the dayside aurora. They are similar to Strong Thermal Emission Velocity Enhancement (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.
We studied the first broad band emissions, called continuum, in the dayside aurora. They are...
