Duskward displacement of plasmoids and reconnection in the near-Earth magnetotail

Abstract Magnetic reconnection in the near-Earth magnetotail is responsible for explosive release of energy during substorms and auroral breakups. This near-tail reconnection was previously assumed to occur around the midnight meridian, where earthward flows were typically observed. Based on observa...

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Main Authors: Akimasa Ieda, Yukinaga Miyashita
Format: Article
Language:English
Published: SpringerOpen 2024-12-01
Series:Earth, Planets and Space
Subjects:
Online Access:https://doi.org/10.1186/s40623-024-02003-w
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author Akimasa Ieda
Yukinaga Miyashita
author_facet Akimasa Ieda
Yukinaga Miyashita
author_sort Akimasa Ieda
collection DOAJ
description Abstract Magnetic reconnection in the near-Earth magnetotail is responsible for explosive release of energy during substorms and auroral breakups. This near-tail reconnection was previously assumed to occur around the midnight meridian, where earthward flows were typically observed. Based on observations of tailward-moving plasmoids, the Geotail spacecraft mission discovered that the reconnection location was displaced toward dusk. This dusk preference is presumably caused by the Hall electric field, as was suggested later in simulations. However, recent spacecraft observations have indicated that the reconnection was displaced toward dawn, and not dusk, in Mercury’s magnetotail. In response to this controversy, our study aims to clarify the dawn–dusk location of fast plasma flows in the near-Earth magnetotail. Through a comprehensive reinterpretation and integration of previous statistical results, we found that the dusk preference is generally evident for tailward flows but is often absent for earthward flows. These results indicate that the statistical results of earthward flows are sensitive to event selection criteria. We conclude that the dawn–dusk location of earthward flow is statistically unclear at the time of substorm onset. Similarly, in the magnetotail of other planets, the dawn–dusk location of planetward flow may be sensitive to event selection criteria. Hence, reconnection may occur predominantly on the duskside in Mercury’s magnetotail. This hypothesis will be tested using observations of tailward-moving plasmoids by the BepiColombo Mio spacecraft, which will begin orbital observations of Mercury in the year 2026. Graphical Abstract
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spelling doaj-art-fa9eaa2ff4194152b82a2e81158285da2025-01-05T12:11:01ZengSpringerOpenEarth, Planets and Space1880-59812024-12-0176111710.1186/s40623-024-02003-wDuskward displacement of plasmoids and reconnection in the near-Earth magnetotailAkimasa Ieda0Yukinaga Miyashita1Institute for Space-Earth Environmental Research, Nagoya UniversitySpace Science Division, Korea Astronomy and Space Science InstituteAbstract Magnetic reconnection in the near-Earth magnetotail is responsible for explosive release of energy during substorms and auroral breakups. This near-tail reconnection was previously assumed to occur around the midnight meridian, where earthward flows were typically observed. Based on observations of tailward-moving plasmoids, the Geotail spacecraft mission discovered that the reconnection location was displaced toward dusk. This dusk preference is presumably caused by the Hall electric field, as was suggested later in simulations. However, recent spacecraft observations have indicated that the reconnection was displaced toward dawn, and not dusk, in Mercury’s magnetotail. In response to this controversy, our study aims to clarify the dawn–dusk location of fast plasma flows in the near-Earth magnetotail. Through a comprehensive reinterpretation and integration of previous statistical results, we found that the dusk preference is generally evident for tailward flows but is often absent for earthward flows. These results indicate that the statistical results of earthward flows are sensitive to event selection criteria. We conclude that the dawn–dusk location of earthward flow is statistically unclear at the time of substorm onset. Similarly, in the magnetotail of other planets, the dawn–dusk location of planetward flow may be sensitive to event selection criteria. Hence, reconnection may occur predominantly on the duskside in Mercury’s magnetotail. This hypothesis will be tested using observations of tailward-moving plasmoids by the BepiColombo Mio spacecraft, which will begin orbital observations of Mercury in the year 2026. Graphical Abstracthttps://doi.org/10.1186/s40623-024-02003-wMagnetotailPlasmoidPlasma flowReconnectionDawn–dusk asymmetryAuroral breakup
spellingShingle Akimasa Ieda
Yukinaga Miyashita
Duskward displacement of plasmoids and reconnection in the near-Earth magnetotail
Earth, Planets and Space
Magnetotail
Plasmoid
Plasma flow
Reconnection
Dawn–dusk asymmetry
Auroral breakup
title Duskward displacement of plasmoids and reconnection in the near-Earth magnetotail
title_full Duskward displacement of plasmoids and reconnection in the near-Earth magnetotail
title_fullStr Duskward displacement of plasmoids and reconnection in the near-Earth magnetotail
title_full_unstemmed Duskward displacement of plasmoids and reconnection in the near-Earth magnetotail
title_short Duskward displacement of plasmoids and reconnection in the near-Earth magnetotail
title_sort duskward displacement of plasmoids and reconnection in the near earth magnetotail
topic Magnetotail
Plasmoid
Plasma flow
Reconnection
Dawn–dusk asymmetry
Auroral breakup
url https://doi.org/10.1186/s40623-024-02003-w
work_keys_str_mv AT akimasaieda duskwarddisplacementofplasmoidsandreconnectioninthenearearthmagnetotail
AT yukinagamiyashita duskwarddisplacementofplasmoidsandreconnectioninthenearearthmagnetotail