Articles | Volume 42, issue 1
https://doi.org/10.5194/angeo-42-229-2024
© 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-42-229-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| Highlight paper
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04 Jun 2024
Regular paper | Highlight paper |
| 04 Jun 2024
| 04 Jun 2024
Does high-latitude ionospheric electrodynamics exhibit hemispheric mirror symmetry?
Department of Physics and Technology, University of Bergen, Bergen, Norway
Heikki Vanhamäki
Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
Karl Magnus Laundal
Department of Physics and Technology, University of Bergen, Bergen, Norway
Jone Peter Reistad
Department of Physics and Technology, University of Bergen, Bergen, Norway
Johnathan K. Burchill
Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
Levan Lomidze
Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
David J. Knudsen
Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
Michael Madelaire
Department of Physics and Technology, University of Bergen, Bergen, Norway
Habtamu Tesfaw
Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
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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.
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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.
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A number of current systems exist in the Earth's magnetosphere. It is very difficult to identify local measurements as belonging to a specific current system. Therefore, there are different definitions of supposedly the same current, leading to unnecessary controversy. This study presents a robust collection of these definitions of current systems in geospace, particularly in the near-Earth nightside magnetosphere, as viewed from a variety of observational and computational analysis techniques.
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Subject: Magnetosphere & space plasma physics | Keywords: Magnetosphere–ionosphere interactions
Multiple conjugate observations of magnetospheric fast flow bursts using THEMIS observations
Ionospheric plasma flows associated with the formation of the distorted nightside end of a transpolar arc
Relation between the asymmetric ring current effect and the anti-sunward auroral currents, as deduced from CHAMP observations
Estimating the fate of oxygen ion outflow from the high-altitude cusp
Hybrid-Vlasov modelling of nightside auroral proton precipitation during southward interplanetary magnetic field conditions
Homayon Aryan, Jacob Bortnik, Jinxing Li, James Michael Weygand, Xiangning Chu, and Vassilis Angelopoulos
Ann. Geophys., 40, 531–544, https://doi.org/10.5194/angeo-40-531-2022, https://doi.org/10.5194/angeo-40-531-2022, 2022
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In this study, we use a multipoint analysis of conjugate magnetospheric and ionospheric observations to investigate the magnetospheric and ionospheric responses to fast flow bursts that are associated with different space weather conditions. The results show that ionospheric currents are connected to the magnetospheric flows for different space weather conditions. The connection is more apparent and global for flows that are associated with a geomagnetically active condition.
Motoharu Nowada, Adrian Grocott, and Quan-Qi Shi
Ann. Geophys., 40, 299–314, https://doi.org/10.5194/angeo-40-299-2022, https://doi.org/10.5194/angeo-40-299-2022, 2022
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We report that the ionospheric plasma flow patterns associated with the J-shaped transpolar arc (a type of nightside distorted TPA), detected by the SuperDARN radar, reveal the formation process of the nightside distortion of a TPA. Equatorward flows at the TPA growth point were observed flowing out of the polar cap and then turning toward the pre-midnight main auroral oval along the TPA nightside distortion. These ionospheric flow patterns would cause the distortion at the TPA nightside end.
Hermann Lühr and Yun-Liang Zhou
Ann. Geophys., 38, 749–764, https://doi.org/10.5194/angeo-38-749-2020, https://doi.org/10.5194/angeo-38-749-2020, 2020
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During magnetic storms the magnetic disturbance at low latitudes becomes asymmetric, enhanced in the evening sector and reduced around morning. This has been attributed to the asymmetric ring current. Here a new 3D current system is proposed for explaining the asymmetric signal. Anti-sunward net currents at high latitude are connected at their noon and night ends to field-aligned currents that lead the currents to the magnetopause on the dawn and dusk flanks where the current closure occurs.
Patrik Krcelic, Stein Haaland, Lukas Maes, Rikard Slapak, and Audrey Schillings
Ann. Geophys., 38, 491–505, https://doi.org/10.5194/angeo-38-491-2020, https://doi.org/10.5194/angeo-38-491-2020, 2020
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In this paper we have used Cluster EDI data in combination with the CODIF cusp dataset from Slapak et al. (2017) to obtain parallel and convection velocities for oxygen ions; 69 % of total oxygen outflow from the high-altitude cusps escapes the magnetosphere on average; 50 % escapes tailward beyond the distant X-line. The oxygen capture-versus-escape ratio is highly dependent on geomagnetic conditions. During active conditions, the majority of oxygen outflow is convected to the plasma sheet.
Maxime Grandin, Markus Battarbee, Adnane Osmane, Urs Ganse, Yann Pfau-Kempf, Lucile Turc, Thiago Brito, Tuomas Koskela, Maxime Dubart, and Minna Palmroth
Ann. Geophys., 37, 791–806, https://doi.org/10.5194/angeo-37-791-2019, https://doi.org/10.5194/angeo-37-791-2019, 2019
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When the terrestrial magnetic field is disturbed, particles from the near-Earth space can precipitate into the upper atmosphere. This work presents, for the first time, numerical simulations of proton precipitation in the energy range associated with the production of aurora (∼1–30 keV) using a global kinetic model of the near-Earth space: Vlasiator. We find that nightside proton precipitation can be regulated by the transition region between stretched and dipolar geomagnetic field lines.
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This paper presents a new set of empirical models for describing variations in ionosphere-thermosphere electrodynamics in both hemispheres, as a function of season as well as prevailing solar wind and interplanetary magnetic field conditions. The models are based on combined measurements of magnetic field perturbations and ionospheric plasma drift made by the Swarm and CHAMP satellites. The chief advantage of these models is that they are the first empirical models of high-latitude ionospheric electrodynamics quantities in both hemispheres that are consistently derived. The model codes are open source and publicly available.
This paper presents a new set of empirical models for describing variations in...
Short summary
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.
In studies of the Earth's ionosphere, a hot topic is how to estimate ionospheric conductivity....
