Does the Dayside Equatorial Ionospheric Electric Field Respond to Isolated Substorms?

Abstract Substorms are known to induce global magnetosphere‐ionosphere coupling. However, the specific response of the dayside ionospheric electric field and its influence on the equatorial electrojet (EEJ) remain controversial. This study investigates the electromagnetic field response in the daysi...

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Main Authors: M. Hayashi, A. Yoshikawa, S. Ohtani
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2025GL115227
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author M. Hayashi
A. Yoshikawa
S. Ohtani
author_facet M. Hayashi
A. Yoshikawa
S. Ohtani
author_sort M. Hayashi
collection DOAJ
description Abstract Substorms are known to induce global magnetosphere‐ionosphere coupling. However, the specific response of the dayside ionospheric electric field and its influence on the equatorial electrojet (EEJ) remain controversial. This study investigates the electromagnetic field response in the dayside equatorial region during isolated substorms using ground magnetic field data. Statistical analysis revealed that the H component decreased at equatorial and low‐latitude stations during isolated substorms. These decreases were of similar magnitude on average, indicating that significant changes in the EEJ caused by penetrating electric fields were not observed. However, individual events showed slight positive and negative variations. These results suggest that substorm‐associated electric fields can reach equatorial regions, but additional conditions determine the positive and negative variations. This finding provides new insights into the spatial extent of substorm‐induced electric fields.
format Article
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institution DOAJ
issn 0094-8276
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publishDate 2025-05-01
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record_format Article
series Geophysical Research Letters
spelling doaj-art-2e164fd40f434ad7a51a8862f860905b2025-08-20T03:10:31ZengWileyGeophysical Research Letters0094-82761944-80072025-05-015210n/an/a10.1029/2025GL115227Does the Dayside Equatorial Ionospheric Electric Field Respond to Isolated Substorms?M. Hayashi0A. Yoshikawa1S. Ohtani2Department of Earth and Planetary Sciences Graduate School of Science Kyushu University Fukuoka JapanDepartment of Earth and Planetary Sciences Faculty of Science Kyushu University Fukuoka JapanJohns Hopkins University Applied Physics Laboratory Laurel MD USAAbstract Substorms are known to induce global magnetosphere‐ionosphere coupling. However, the specific response of the dayside ionospheric electric field and its influence on the equatorial electrojet (EEJ) remain controversial. This study investigates the electromagnetic field response in the dayside equatorial region during isolated substorms using ground magnetic field data. Statistical analysis revealed that the H component decreased at equatorial and low‐latitude stations during isolated substorms. These decreases were of similar magnitude on average, indicating that significant changes in the EEJ caused by penetrating electric fields were not observed. However, individual events showed slight positive and negative variations. These results suggest that substorm‐associated electric fields can reach equatorial regions, but additional conditions determine the positive and negative variations. This finding provides new insights into the spatial extent of substorm‐induced electric fields.https://doi.org/10.1029/2025GL115227substormionosphereequatormagnetosphere
spellingShingle M. Hayashi
A. Yoshikawa
S. Ohtani
Does the Dayside Equatorial Ionospheric Electric Field Respond to Isolated Substorms?
Geophysical Research Letters
substorm
ionosphere
equator
magnetosphere
title Does the Dayside Equatorial Ionospheric Electric Field Respond to Isolated Substorms?
title_full Does the Dayside Equatorial Ionospheric Electric Field Respond to Isolated Substorms?
title_fullStr Does the Dayside Equatorial Ionospheric Electric Field Respond to Isolated Substorms?
title_full_unstemmed Does the Dayside Equatorial Ionospheric Electric Field Respond to Isolated Substorms?
title_short Does the Dayside Equatorial Ionospheric Electric Field Respond to Isolated Substorms?
title_sort does the dayside equatorial ionospheric electric field respond to isolated substorms
topic substorm
ionosphere
equator
magnetosphere
url https://doi.org/10.1029/2025GL115227
work_keys_str_mv AT mhayashi doesthedaysideequatorialionosphericelectricfieldrespondtoisolatedsubstorms
AT ayoshikawa doesthedaysideequatorialionosphericelectricfieldrespondtoisolatedsubstorms
AT sohtani doesthedaysideequatorialionosphericelectricfieldrespondtoisolatedsubstorms