Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study
Abstract In this study, we investigate the effects caused by interplanetary (IP) shock impact angles on the subsequent ground dB/dt variations during substorms. IP shock impact angles have been revealed as a major factor controlling the subsequent geomagnetic activity, meaning that shocks with small...
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Wiley
2024-03-01
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| Series: | Space Weather |
| Online Access: | https://doi.org/10.1029/2023SW003767 |
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| author | Denny M. Oliveira James M. Weygand John C. Coxon Eftyhia Zesta |
| author_facet | Denny M. Oliveira James M. Weygand John C. Coxon Eftyhia Zesta |
| author_sort | Denny M. Oliveira |
| collection | DOAJ |
| description | Abstract In this study, we investigate the effects caused by interplanetary (IP) shock impact angles on the subsequent ground dB/dt variations during substorms. IP shock impact angles have been revealed as a major factor controlling the subsequent geomagnetic activity, meaning that shocks with small inclinations with the Sun‐Earth line are more likely to trigger higher geomagnetic activity resulting from nearly symmetric magnetospheric compressions. Such field variations are linked to the generation of geomagnetically induced currents (GICs), which couple to artificial conductors on the ground leading to deleterious consequences. We use a sub‐set of a shock data base with 237 events observed in the solar wind at L1 upstream of the Earth, and large arrays of ground magnetometers at stations located in North America and Greenland. The spherical elementary current system methodology is applied to the geomagnetic field data, and field‐aligned‐like currents in the ionosphere are derived. Then, such currents are inverted back to the ground and dB/dt variations are computed. Geographic maps are built with these field variations as a function of shock impact angles. The main findings of this investigation are: (a) typical dB/dt variations (5–10 nT/s) are caused by shocks with moderate inclinations; (b) the more frontal the shock impact, the more intense and the more spatially defined the ionospheric current amplitudes; and (c) nearly frontal shocks trigger more intense dB/dt variations with larger equatorward latitudinal expansions. Therefore, the findings of this work provide new insights for GIC forecasting focusing on nearly frontal shock impacts on the magnetosphere. |
| format | Article |
| id | doaj-art-7296261b50fc4e859681d9020f901d9c |
| institution | Kabale University |
| issn | 1542-7390 |
| language | English |
| publishDate | 2024-03-01 |
| publisher | Wiley |
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| spelling | doaj-art-7296261b50fc4e859681d9020f901d9c2025-01-14T16:30:30ZengWileySpace Weather1542-73902024-03-01223n/an/a10.1029/2023SW003767Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical StudyDenny M. Oliveira0James M. Weygand1John C. Coxon2Eftyhia Zesta3Goddard Planetary Heliophysics Institute University of Maryland Baltimore MD USADepartment of Earth, Planetary, and Space Sciences University of California Los Angeles Los Angeles CA USADepartment of Mathematics, Physics and Electrical Engineering Newcastle Upon Tyne UKGeospace Physics Laboratory NASA Goddard Space Flight Center Greenbelt MD USAAbstract In this study, we investigate the effects caused by interplanetary (IP) shock impact angles on the subsequent ground dB/dt variations during substorms. IP shock impact angles have been revealed as a major factor controlling the subsequent geomagnetic activity, meaning that shocks with small inclinations with the Sun‐Earth line are more likely to trigger higher geomagnetic activity resulting from nearly symmetric magnetospheric compressions. Such field variations are linked to the generation of geomagnetically induced currents (GICs), which couple to artificial conductors on the ground leading to deleterious consequences. We use a sub‐set of a shock data base with 237 events observed in the solar wind at L1 upstream of the Earth, and large arrays of ground magnetometers at stations located in North America and Greenland. The spherical elementary current system methodology is applied to the geomagnetic field data, and field‐aligned‐like currents in the ionosphere are derived. Then, such currents are inverted back to the ground and dB/dt variations are computed. Geographic maps are built with these field variations as a function of shock impact angles. The main findings of this investigation are: (a) typical dB/dt variations (5–10 nT/s) are caused by shocks with moderate inclinations; (b) the more frontal the shock impact, the more intense and the more spatially defined the ionospheric current amplitudes; and (c) nearly frontal shocks trigger more intense dB/dt variations with larger equatorward latitudinal expansions. Therefore, the findings of this work provide new insights for GIC forecasting focusing on nearly frontal shock impacts on the magnetosphere.https://doi.org/10.1029/2023SW003767 |
| spellingShingle | Denny M. Oliveira James M. Weygand John C. Coxon Eftyhia Zesta Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study Space Weather |
| title | Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study |
| title_full | Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study |
| title_fullStr | Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study |
| title_full_unstemmed | Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study |
| title_short | Substorm‐Time Ground dB/dt Variations Controlled by Interplanetary Shock Impact Angles: A Statistical Study |
| title_sort | substorm time ground db dt variations controlled by interplanetary shock impact angles a statistical study |
| url | https://doi.org/10.1029/2023SW003767 |
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