Articles | Volume 44, issue 2
https://doi.org/10.5194/angeo-44-697-2026
© Author(s) 2026. 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-44-697-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
28 Jul 2026
Regular paper |
| 28 Jul 2026
| 28 Jul 2026
High-latitude observations of ULF wave driven ion upflow
Charlotte M. van Hazendonk
CORRESPONDING AUTHOR
Department of Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
Department of Physics and Technology, University of Bergen, Norway
Lisa J. Baddeley
Department of Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
Department of Physics, University of Oslo, Norway
Karl M. Laundal
Division of Geomagnetism and Geospace, DTU Space, Technical University of Denmark, Copenhagen, Denmark
Department of Physics and Technology, University of Bergen, Norway
Noora Partamies
Department of Arctic Geophysics, The University Centre in Svalbard, Longyearbyen, Norway
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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
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
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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.
Jens Christian Hessen, Jone Peter Reistad, Spencer Mark Hatch, Karl Magnus Laundal, and Yongliang Zhang
Ann. Geophys., 44, 405–433, https://doi.org/10.5194/angeo-44-405-2026, https://doi.org/10.5194/angeo-44-405-2026, 2026
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Auroras, the natural lights seen in Earth's sky near the poles, are shaped by both Earth's and the solar wind's magnetic fields, as well as charged solar particles. This study examines how auroras change when the solar wind's magnetic field is dawn-dusk oriented. Daytime observations are challenging due to sunlight, so we developed a method to further separate auroras from background light. In summer, auroras shift east or west with/against the solar wind's magnetic field.
Spencer Mark Hatch, Johnathan K. Burchill, Heikki Vanhamäki, Rafael Luiz Araujo de Mesquita, and Karl Magnus Laundal
EGUsphere, https://doi.org/10.5194/egusphere-2026-940, https://doi.org/10.5194/egusphere-2026-940, 2026
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Atmospheric winds at high altitudes (> 100 km) can play an important role in the electrodynamic processes that govern how ionospheric plasma interacts with Earth's neutral atmosphere. Here we investigate how a common idea in studies of ionospheric electrodynamics—that atmospheric winds can be ignored or represented via an average value—ignores the high variability of these winds. This variability forces a different formulation of the equations that govern ionosphere-thermosphere electrodynamics.
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.
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
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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.
Karl M. Laundal, Andreas S. Skeidsvoll, Beatrice Popescu Braileanu, Spencer M. Hatch, Nils Olsen, and Heikki Vanhamäki
Ann. Geophys., 43, 803–833, https://doi.org/10.5194/angeo-43-803-2025, https://doi.org/10.5194/angeo-43-803-2025, 2025
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The ionosphere is where Earth’s atmosphere overlaps with a gas of charged particles in space. There, collisions with neutral air and electromagnetic forces driven by the solar wind control plasma motion. We created a global model that includes magnetic induction, explaining how electric currents and fields change, offering a more accurate view of atmosphere–space coupling than conventional models based on electric circuits.
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.
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.
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.
Hanne H. Christiansen, Ilkka S. O. Matero, Lisa Baddeley, Kim Holmén, Clara J. M. Hoppe, Maarten J. J. E. Loonen, Rune Storvold, Vito Vitale, Agata Zaborska, and Heikki Lihavainen
Earth Syst. Dynam., 15, 933–946, https://doi.org/10.5194/esd-15-933-2024, https://doi.org/10.5194/esd-15-933-2024, 2024
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We provide an overview of the state and future of Earth system science in Svalbard as a synthesis of the recommendations made by the scientific community active in the archipelago. This work helped identify foci for developments of the observing system and a path forward to reach the full interdisciplinarity needed to operate at Earth system science scale. Better understanding of the processes in Svalbard will benefit both process-level understanding and Earth system models.
Spencer Mark Hatch, Heikki Vanhamäki, Karl Magnus Laundal, Jone Peter Reistad, Johnathan K. Burchill, Levan Lomidze, David J. Knudsen, Michael Madelaire, and Habtamu Tesfaw
Ann. Geophys., 42, 229–253, https://doi.org/10.5194/angeo-42-229-2024, https://doi.org/10.5194/angeo-42-229-2024, 2024
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In studies of the Earth's ionosphere, a hot topic is how to estimate ionospheric conductivity. This is hard to do for a variety of reasons that mostly amount to a lack of measurements. In this study we use satellite measurements to estimate electromagnetic work and ionospheric conductances in both hemispheres. We identify where our model estimates are inconsistent with laws of physics, which partially solves a previous problem with unrealistic predictions of ionospheric conductances.
Liisa Juusola, Ari Viljanen, Noora Partamies, Heikki Vanhamäki, Mirjam Kellinsalmi, and Simon Walker
Ann. Geophys., 41, 483–510, https://doi.org/10.5194/angeo-41-483-2023, https://doi.org/10.5194/angeo-41-483-2023, 2023
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At times when auroras erupt on the sky, the magnetic field surrounding the Earth undergoes rapid changes. On the ground, these changes can induce harmful electric currents in technological conductor networks, such as powerlines. We have used magnetic field observations from northern Europe during 28 such events and found consistent behavior that can help to understand, and thus predict, the processes that drive auroras and geomagnetically induced currents.
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.
Nataliya Sergeevna Nosikova, Nadezda Viktorovna Yagova, Lisa Jane Baddeley, Dag Arne Lorentzen, and Dmitriy Anatolyevich Sormakov
Ann. Geophys., 40, 151–165, https://doi.org/10.5194/angeo-40-151-2022, https://doi.org/10.5194/angeo-40-151-2022, 2022
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This paper presents a study of millihertz magnetic pulsations seen in the magnetosphere and on the Earth under quiet space weather conditions. We found that these fluctuations appear in the magnetosphere as soon as disturbances with the same frequency vanish in the solar wind. The results of this work show the possibility of a substorm developing under absolutely quiet external conditions and allow us to assume that these pulsations represent a substorm preparatory phase.
Derek McKay, Juha Vierinen, Antti Kero, and Noora Partamies
Geosci. Instrum. Method. Data Syst., 11, 25–35, https://doi.org/10.5194/gi-11-25-2022, https://doi.org/10.5194/gi-11-25-2022, 2022
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When radio waves from our galaxy enter the Earth's atmosphere, they are absorbed by electrons in the upper atmosphere. It was thought that by measuring the amount of absorption, it would allow the height of these electrons in the atmosphere to be determined. If so, this would have significance for future instrument design. However, this paper demonstrates that it is not possible to do this, but it does explain how multiple-frequency measurements can nevertheless be useful.
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.
Florine Enengl, Noora Partamies, Nickolay Ivchenko, and Lisa Baddeley
Ann. Geophys., 39, 795–809, https://doi.org/10.5194/angeo-39-795-2021, https://doi.org/10.5194/angeo-39-795-2021, 2021
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Energetic particle precipitation has the potential to change the neutral atmospheric temperature at the bottom of the ionosphere. We have searched for events and investigated a possible correlation between lower-ionosphere electron density enhancements and simultaneous neutral temperature changes. Six of the 10 analysed events are associated with a temperature decrease of 10–20K. The events change the chemical composition in the mesosphere, and the temperatures are probed at lower altitudes.
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Short summary
This study shows the first observations of the upflow of ions in the Earth's ionosphere generated by ultra-low frequency waves. These waves are visible as auroral arcs. Using various instruments and models, their complex dynamics and the coupling between the ionosphere and magnetosphere were highlighted. Results show significant energy dissipation and currents, even from small-scale waves, highlighting the importance of a multi-instrument approach to understanding such phenomena.
This study shows the first observations of the upflow of ions in the Earth's ionosphere...
