Articles | Volume 42, issue 2
https://doi.org/10.5194/angeo-42-355-2024
© Author(s) 2024. 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-42-355-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
06 Sep 2024
Regular paper |
| 06 Sep 2024
| 06 Sep 2024
Statistical comparison of electron precipitation during auroral breakups occurring either near the open–closed field line boundary or in the central part of the auroral oval
Maxime Grandin
CORRESPONDING AUTHOR
Department of Physics, University of Helsinki, Helsinki, Finland
Noora Partamies
Department of Arctic Geophysics, University Centre in Svalbard, Longyearbyen, Norway
Ilkka I. Virtanen
Space Physics and Astronomy, University of Oulu, Oulu, Finland
Related authors
Gaël Cessateur, Christian Buil, Guillaume Bertrand, Matthieu Le Lain, Valérie Desnoux, Olivier Garde, Hervé Lamy, Mathieu Barthelemy, Magnar Gullikstad Johnsen, David Bolsée, Urban Brändström, Antoine Calegaro, Fabien Darrouzet, Rowan Dayton-Oxland, Johan De Keyser, Maxime Grandin, Kirsti Kauristie, Romain Maggiolo, Sota Nanjo, and Noora Partamies
EGUsphere, https://doi.org/10.5194/egusphere-2026-5461, https://doi.org/10.5194/egusphere-2026-5461, 2026
This preprint is open for discussion and under review for Geoscientific Instrumentation, Methods and Data Systems (GI).
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We developed a compact, portable instrument that records the colours of auroras across a broad range of visible and near-infrared light. Field tests in northern Norway showed that it can capture several important auroral emissions at the same time and can be operated with simple portable equipment. This makes it suitable for coordinated observations from multiple sites, helping researchers study how auroras vary in space and time.
Jia Jia, Yvan Orsolini, Monika E. Szeląg, Antti Kero, Pekka T. Verronen, Maxime Grandin, Patrick J. Espy, Sebastian Käki, Neethal Thomas, Max van de Kamp, Sergey Koldobskiy, Jiarong Zhang, and Noora Partamies
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This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
Short summary
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Geomagnetic storms connect space weather to Earth's atmosphere. Analysing four major Solar Cycle 25 storms, we show that energetic particles cause mesospheric ozone losses of up to 80 %, with distinct responses to energetic electron precipitation and solar proton events. Combining observations and simulations reveals shortcomings in current representations of upper-atmospheric coupling and points to the need for sustained measurements of energetic particles and atmospheric composition.
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
Ann. Geophys., 44, 855–880, https://doi.org/10.5194/angeo-44-855-2026, https://doi.org/10.5194/angeo-44-855-2026, 2026
Short summary
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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 308 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.
Lena Mielke, Katie Herlingshaw, Noora Partamies, Maxime Grandin, Emma Bruus, Rowan Dayton-Oxland, Donna Lach, Marjan Spijkers, Vincent Ledvina, Eero Karvinen, Andres Spicher, Benjamin Eberhardt, and Olivier Staiger
EGUsphere, https://doi.org/10.5194/egusphere-2026-3756, https://doi.org/10.5194/egusphere-2026-3756, 2026
Short summary
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This study presents 26 citizen science observations of fragmented aurora-like emissions, here called fragments, from around the world. Using auroral images and satellite and solar wind data, we found that these short-lived fragments appear across a wide range of magnetic latitudes and local times. They can occur not only poleward of the auroral oval, but also within and equatorward of it. These findings broaden where fragments are known to occur and highlight the value of citizen science.
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
Ann. Geophys., 44, 227–243, https://doi.org/10.5194/angeo-44-227-2026, https://doi.org/10.5194/angeo-44-227-2026, 2026
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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.
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.
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.
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 E. Ledvina
Ann. Geophys., 43, 349–367, https://doi.org/10.5194/angeo-43-349-2025, https://doi.org/10.5194/angeo-43-349-2025, 2025
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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.
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.
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.
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
Short summary
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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.
Gaël Cessateur, Christian Buil, Guillaume Bertrand, Matthieu Le Lain, Valérie Desnoux, Olivier Garde, Hervé Lamy, Mathieu Barthelemy, Magnar Gullikstad Johnsen, David Bolsée, Urban Brändström, Antoine Calegaro, Fabien Darrouzet, Rowan Dayton-Oxland, Johan De Keyser, Maxime Grandin, Kirsti Kauristie, Romain Maggiolo, Sota Nanjo, and Noora Partamies
EGUsphere, https://doi.org/10.5194/egusphere-2026-5461, https://doi.org/10.5194/egusphere-2026-5461, 2026
This preprint is open for discussion and under review for Geoscientific Instrumentation, Methods and Data Systems (GI).
Short summary
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We developed a compact, portable instrument that records the colours of auroras across a broad range of visible and near-infrared light. Field tests in northern Norway showed that it can capture several important auroral emissions at the same time and can be operated with simple portable equipment. This makes it suitable for coordinated observations from multiple sites, helping researchers study how auroras vary in space and time.
Jia Jia, Yvan Orsolini, Monika E. Szeląg, Antti Kero, Pekka T. Verronen, Maxime Grandin, Patrick J. Espy, Sebastian Käki, Neethal Thomas, Max van de Kamp, Sergey Koldobskiy, Jiarong Zhang, and Noora Partamies
EGUsphere, https://doi.org/10.5194/egusphere-2026-5829, https://doi.org/10.5194/egusphere-2026-5829, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
Short summary
Short summary
Geomagnetic storms connect space weather to Earth's atmosphere. Analysing four major Solar Cycle 25 storms, we show that energetic particles cause mesospheric ozone losses of up to 80 %, with distinct responses to energetic electron precipitation and solar proton events. Combining observations and simulations reveals shortcomings in current representations of upper-atmospheric coupling and points to the need for sustained measurements of energetic particles and atmospheric composition.
Noora Partamies and Mikko Syrjäsuo
Ann. Geophys., 44, 1003–1022, https://doi.org/10.5194/angeo-44-1003-2026, https://doi.org/10.5194/angeo-44-1003-2026, 2026
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We developed a method to prune colour all-sky images into classes of clear or cloudy skies with and without aurora using supervised learning and pre-trained convolutional neural network. We investigate a 10-year database of auroral images taken from Svalbard. The method accuracy is well over 90 %, and the results show that about 2/3 of auroral images are cloudy with the cloudiest month being November. Aurora are most often observed in the morning hours independent on the solar activity.
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
Ann. Geophys., 44, 855–880, https://doi.org/10.5194/angeo-44-855-2026, https://doi.org/10.5194/angeo-44-855-2026, 2026
Short summary
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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 308 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.
Lena Mielke, Katie Herlingshaw, Noora Partamies, Maxime Grandin, Emma Bruus, Rowan Dayton-Oxland, Donna Lach, Marjan Spijkers, Vincent Ledvina, Eero Karvinen, Andres Spicher, Benjamin Eberhardt, and Olivier Staiger
EGUsphere, https://doi.org/10.5194/egusphere-2026-3756, https://doi.org/10.5194/egusphere-2026-3756, 2026
Short summary
Short summary
This study presents 26 citizen science observations of fragmented aurora-like emissions, here called fragments, from around the world. Using auroral images and satellite and solar wind data, we found that these short-lived fragments appear across a wide range of magnetic latitudes and local times. They can occur not only poleward of the auroral oval, but also within and equatorward of it. These findings broaden where fragments are known to occur and highlight the value of citizen science.
Harriet George, Andrew P. Dimmock, Vanina Lanabare, Heikki Vanhamäki, Ilkka Virtanen, Anita Aikio, Adrian Blagau, Octav Marghitu, Milla Myllymaa, Habtamu Tesfaw, Stephan Buchert, and Mykhaylo Shumko
EGUsphere, https://doi.org/10.5194/egusphere-2026-3108, https://doi.org/10.5194/egusphere-2026-3108, 2026
Short summary
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Bursty bulk flows are mesoscale ion flows that are ejected from magnetic reconnection sites in the Earth's magnetotail, and they couple to the ionosphere via field aligned currents that close through the ionosphere. We analyse unique triple-conjunctive observations of the coupled bursty bulk flow / current / ionosphere system to evaluate a case study of a bursty bulk flow and its ionospheric effects. We identify multiple current signatures of this bursty bulk flow within the ionosphere.
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
Ann. Geophys., 44, 227–243, https://doi.org/10.5194/angeo-44-227-2026, https://doi.org/10.5194/angeo-44-227-2026, 2026
Short summary
Short summary
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
Ann. Geophys., 44, 123–135, https://doi.org/10.5194/angeo-44-123-2026, https://doi.org/10.5194/angeo-44-123-2026, 2026
Short summary
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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 incoherent scatter radar (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.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
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 E. Ledvina
Ann. Geophys., 43, 349–367, https://doi.org/10.5194/angeo-43-349-2025, https://doi.org/10.5194/angeo-43-349-2025, 2025
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
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.
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.
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Short summary
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.
Auroral displays typically take place at high latitudes, but the exact latitude where the...
