Explicit IMF By Dependence in Geomagnetic Activity: Modulation of Precipitating Electrons
Abstract The most important driver of geomagnetic activity is the north–south ( Bz) component of the interplanetary magnetic field (IMF), which dominates the solar wind‐magnetosphere coupling and all solar wind coupling functions. While the east–west ( By) IMF component is also included in most coup...
| 發表在: | Geophysical Research Letters |
|---|---|
| Main Authors: | , , |
| 格式: | Article |
| 語言: | 英语 |
| 出版: |
Wiley
2020-02-01
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| 主題: | |
| 在線閱讀: | https://doi.org/10.1029/2019GL086676 |
| _version_ | 1850299323529560064 |
|---|---|
| author | L. Holappa T. Asikainen K. Mursula |
| author_facet | L. Holappa T. Asikainen K. Mursula |
| author_sort | L. Holappa |
| collection | DOAJ |
| container_title | Geophysical Research Letters |
| description | Abstract The most important driver of geomagnetic activity is the north–south ( Bz) component of the interplanetary magnetic field (IMF), which dominates the solar wind‐magnetosphere coupling and all solar wind coupling functions. While the east–west ( By) IMF component is also included in most coupling functions, its effect is always assumed to be symmetric with respect of its sign. However, recent studies have shown that, for a fixed value of any coupling function, geomagnetic activity is stronger for By>0 than for By<0 in Northern Hemisphere winter. In Southern Hemisphere winter, the dependence on the By sign is reversed. In this paper, we use measurements of National Oceanic and Atmospheric Administration Polar‐Orbiting Operational Environmental Satellites to show that the flux of magnetospheric electrons precipitating into the atmosphere also exhibits an explicit By dependence. This By dependence is strong in the midnight and dawn sectors where it causes a related By effect in the westward electrojet and geomagnetic activity by modulating ionospheric conductivity. |
| format | Article |
| id | doaj-art-4c464e79613a4bc8a2e6b74f53e87f7e |
| institution | Directory of Open Access Journals |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2020-02-01 |
| publisher | Wiley |
| record_format | Article |
| spelling | doaj-art-4c464e79613a4bc8a2e6b74f53e87f7e2025-08-19T23:31:48ZengWileyGeophysical Research Letters0094-82761944-80072020-02-01474n/an/a10.1029/2019GL086676Explicit IMF By Dependence in Geomagnetic Activity: Modulation of Precipitating ElectronsL. Holappa0T. Asikainen1K. Mursula2ReSoLVE Centre of Excellence, Space Physics and Astronomy Research Unit University of Oulu Oulu FinlandReSoLVE Centre of Excellence, Space Physics and Astronomy Research Unit University of Oulu Oulu FinlandReSoLVE Centre of Excellence, Space Physics and Astronomy Research Unit University of Oulu Oulu FinlandAbstract The most important driver of geomagnetic activity is the north–south ( Bz) component of the interplanetary magnetic field (IMF), which dominates the solar wind‐magnetosphere coupling and all solar wind coupling functions. While the east–west ( By) IMF component is also included in most coupling functions, its effect is always assumed to be symmetric with respect of its sign. However, recent studies have shown that, for a fixed value of any coupling function, geomagnetic activity is stronger for By>0 than for By<0 in Northern Hemisphere winter. In Southern Hemisphere winter, the dependence on the By sign is reversed. In this paper, we use measurements of National Oceanic and Atmospheric Administration Polar‐Orbiting Operational Environmental Satellites to show that the flux of magnetospheric electrons precipitating into the atmosphere also exhibits an explicit By dependence. This By dependence is strong in the midnight and dawn sectors where it causes a related By effect in the westward electrojet and geomagnetic activity by modulating ionospheric conductivity.https://doi.org/10.1029/2019GL086676geomagnetic activityspace weathersolar windionospheremagnetosphereenergetic particles |
| spellingShingle | L. Holappa T. Asikainen K. Mursula Explicit IMF By Dependence in Geomagnetic Activity: Modulation of Precipitating Electrons geomagnetic activity space weather solar wind ionosphere magnetosphere energetic particles |
| title | Explicit IMF By Dependence in Geomagnetic Activity: Modulation of Precipitating Electrons |
| title_full | Explicit IMF By Dependence in Geomagnetic Activity: Modulation of Precipitating Electrons |
| title_fullStr | Explicit IMF By Dependence in Geomagnetic Activity: Modulation of Precipitating Electrons |
| title_full_unstemmed | Explicit IMF By Dependence in Geomagnetic Activity: Modulation of Precipitating Electrons |
| title_short | Explicit IMF By Dependence in Geomagnetic Activity: Modulation of Precipitating Electrons |
| title_sort | explicit imf by dependence in geomagnetic activity modulation of precipitating electrons |
| topic | geomagnetic activity space weather solar wind ionosphere magnetosphere energetic particles |
| url | https://doi.org/10.1029/2019GL086676 |
| work_keys_str_mv | AT lholappa explicitimfbydependenceingeomagneticactivitymodulationofprecipitatingelectrons AT tasikainen explicitimfbydependenceingeomagneticactivitymodulationofprecipitatingelectrons AT kmursula explicitimfbydependenceingeomagneticactivitymodulationofprecipitatingelectrons |