Impact Angle Control of Local Intense dB/dt Variations During Shock‐Induced Substorms
Abstract The impact of interplanetary shocks on the magnetosphere can trigger magnetic substorms that intensify auroral electrojet currents. These currents enhance ground magnetic field perturbations (dB/dt), which in turn generate geomagnetically induced currents (GICs) that can be detrimental to p...
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Wiley
2021-12-01
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| Series: | Space Weather |
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| Online Access: | https://doi.org/10.1029/2021SW002933 |
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| author | Denny M. Oliveira James M. Weygand Eftyhia Zesta Chigomezyo M. Ngwira Michael D. Hartinger Zhonghua Xu Barbara L. Giles Daniel J. Gershman Marcos V. D. Silveira Vítor M. Souza |
| author_facet | Denny M. Oliveira James M. Weygand Eftyhia Zesta Chigomezyo M. Ngwira Michael D. Hartinger Zhonghua Xu Barbara L. Giles Daniel J. Gershman Marcos V. D. Silveira Vítor M. Souza |
| author_sort | Denny M. Oliveira |
| collection | DOAJ |
| description | Abstract The impact of interplanetary shocks on the magnetosphere can trigger magnetic substorms that intensify auroral electrojet currents. These currents enhance ground magnetic field perturbations (dB/dt), which in turn generate geomagnetically induced currents (GICs) that can be detrimental to power transmission infrastructure. We perform a comparative study of dB/dt variations in response to two similarly strong shocks, but with one being nearly frontal and the other highly inclined. Multi‐instrument analyses by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Los Alamos National Laboratory spacecraft show that nightside substorm‐time energetic particle injections are more intense and occur faster in the case of the nearly head‐on impact. The same trend is observed in dB/dt variations recorded by THEMIS ground magnetometers. THEMIS all‐sky imager data show a fast and clear poleward auroral expansion in the first case, which does not clearly occur in the second case. Strong field‐aligned currents computed with the spherical elementary current system (SECS) technique occur in both cases, but the current variations resulting from the inclined shock impact are weaker and slower compared to the nearly frontal case. SECS analyses also reveal that geographic areas with dB/dt surpassing the thresholds 1.5 and 5 nT/s, usually linked to high‐risk GICs, are larger and occur earlier due to the symmetric compression caused by the nearly head‐on impact. These results, with profound space weather implications, suggest that shock impact angles affect the geospace driving conditions and the location and intensity of the subsequent dB/dt variations during substorm activity. |
| format | Article |
| id | doaj-art-2b2f3ae525ce469ca97bb5d94c16dc90 |
| institution | Kabale University |
| issn | 1542-7390 |
| language | English |
| publishDate | 2021-12-01 |
| publisher | Wiley |
| record_format | Article |
| series | Space Weather |
| spelling | doaj-art-2b2f3ae525ce469ca97bb5d94c16dc902025-01-14T16:27:22ZengWileySpace Weather1542-73902021-12-011912n/an/a10.1029/2021SW002933Impact Angle Control of Local Intense dB/dt Variations During Shock‐Induced SubstormsDenny M. Oliveira0James M. Weygand1Eftyhia Zesta2Chigomezyo M. Ngwira3Michael D. Hartinger4Zhonghua Xu5Barbara L. Giles6Daniel J. Gershman7Marcos V. D. Silveira8Vítor M. Souza9Goddard Planetary Heliophysics Institute University of Maryland, Baltimore County Baltimore MD USADepartment of Earth, Planetary, and Space Sciences University of California Los Angeles Los Angeles CA USAHeliophysics Science Division NASA Goddard Space Flight Center Greenbelt MD USAAtmospheric and Space Technology Research Associates LLC Louisville CO USASpace Science Institute Boulder CO USACenter for Space Science and Engineering Research Virginia Tech Blacksburg VA USAHeliophysics Science Division NASA Goddard Space Flight Center Greenbelt MD USAHeliophysics Science Division NASA Goddard Space Flight Center Greenbelt MD USANational Institute for Space Research – INPE São José dos Campos BrazilNational Institute for Space Research – INPE São José dos Campos BrazilAbstract The impact of interplanetary shocks on the magnetosphere can trigger magnetic substorms that intensify auroral electrojet currents. These currents enhance ground magnetic field perturbations (dB/dt), which in turn generate geomagnetically induced currents (GICs) that can be detrimental to power transmission infrastructure. We perform a comparative study of dB/dt variations in response to two similarly strong shocks, but with one being nearly frontal and the other highly inclined. Multi‐instrument analyses by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Los Alamos National Laboratory spacecraft show that nightside substorm‐time energetic particle injections are more intense and occur faster in the case of the nearly head‐on impact. The same trend is observed in dB/dt variations recorded by THEMIS ground magnetometers. THEMIS all‐sky imager data show a fast and clear poleward auroral expansion in the first case, which does not clearly occur in the second case. Strong field‐aligned currents computed with the spherical elementary current system (SECS) technique occur in both cases, but the current variations resulting from the inclined shock impact are weaker and slower compared to the nearly frontal case. SECS analyses also reveal that geographic areas with dB/dt surpassing the thresholds 1.5 and 5 nT/s, usually linked to high‐risk GICs, are larger and occur earlier due to the symmetric compression caused by the nearly head‐on impact. These results, with profound space weather implications, suggest that shock impact angles affect the geospace driving conditions and the location and intensity of the subsequent dB/dt variations during substorm activity.https://doi.org/10.1029/2021SW002933interplanetary shocksshock impact angleauroral substormsgeomagnetically induced currents |
| spellingShingle | Denny M. Oliveira James M. Weygand Eftyhia Zesta Chigomezyo M. Ngwira Michael D. Hartinger Zhonghua Xu Barbara L. Giles Daniel J. Gershman Marcos V. D. Silveira Vítor M. Souza Impact Angle Control of Local Intense dB/dt Variations During Shock‐Induced Substorms Space Weather interplanetary shocks shock impact angle auroral substorms geomagnetically induced currents |
| title | Impact Angle Control of Local Intense dB/dt Variations During Shock‐Induced Substorms |
| title_full | Impact Angle Control of Local Intense dB/dt Variations During Shock‐Induced Substorms |
| title_fullStr | Impact Angle Control of Local Intense dB/dt Variations During Shock‐Induced Substorms |
| title_full_unstemmed | Impact Angle Control of Local Intense dB/dt Variations During Shock‐Induced Substorms |
| title_short | Impact Angle Control of Local Intense dB/dt Variations During Shock‐Induced Substorms |
| title_sort | impact angle control of local intense db dt variations during shock induced substorms |
| topic | interplanetary shocks shock impact angle auroral substorms geomagnetically induced currents |
| url | https://doi.org/10.1029/2021SW002933 |
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