Distribution of equatorial Alfvén velocity in the magnetosphere: a statistical analysis of THEMIS observations
Abstract It has been known that the Alfvén velocity plays a significant role in generation and propagation of magnetohydrodynamic (MHD) waves. Until now, however, the global distribution of the Alfvén velocity in the magnetosphere has not been reported. To determine the spatial distribution of the A...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2018-11-01
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| Series: | Earth, Planets and Space |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s40623-018-0947-9 |
| _version_ | 1830409540592467968 |
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| author | Khan-Hyuk Kim Gi-Jeong Kim Hyuck-Jin Kwon |
| author_facet | Khan-Hyuk Kim Gi-Jeong Kim Hyuck-Jin Kwon |
| author_sort | Khan-Hyuk Kim |
| collection | DOAJ |
| description | Abstract It has been known that the Alfvén velocity plays a significant role in generation and propagation of magnetohydrodynamic (MHD) waves. Until now, however, the global distribution of the Alfvén velocity in the magnetosphere has not been reported. To determine the spatial distribution of the Alfvén velocity, we have statistically examined the THEMIS magnetic field and electron density data obtained in the L (the equatorial geocentric distance to the field line measured in Earth’s radii) range of ~ 4–12 and at all local times near the magnetic equator between − 5° and 5° in magnetic latitude for 2008–2014. We observed a pronounced dawn–dusk asymmetry in the equatorial Alfvén velocity calculated from the THEMIS magnetic field and density data. That is, the dawnside Alfvén velocity is higher than the duskside Alfvén velocity. This asymmetry is due to the duskside bulge in the plasmasphere. The radial profile of the Alfvén velocity shows an increasing function of L between L = 4 and 10 in the dusk sector, while a decreasing function in the dawn sector. By comparing these Alfvén velocity distributions along the local time and radial distance, we discuss the occurrence distribution and propagation of MHD waves in the outer magnetosphere. |
| first_indexed | 2024-12-20T19:15:13Z |
| format | Article |
| id | doaj.art-1225322670934501a08b8b1a0da9ac2c |
| institution | Directory Open Access Journal |
| issn | 1880-5981 |
| language | English |
| last_indexed | 2024-12-20T19:15:13Z |
| publishDate | 2018-11-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Earth, Planets and Space |
| spelling | doaj.art-1225322670934501a08b8b1a0da9ac2c2022-12-21T19:29:08ZengSpringerOpenEarth, Planets and Space1880-59812018-11-017011710.1186/s40623-018-0947-9Distribution of equatorial Alfvén velocity in the magnetosphere: a statistical analysis of THEMIS observationsKhan-Hyuk Kim0Gi-Jeong Kim1Hyuck-Jin Kwon2School of Space Research, Kyung-Hee UniversitySchool of Space Research, Kyung-Hee UniversityDivision of Polar Climate Sciences, Korea Polar Research InstituteAbstract It has been known that the Alfvén velocity plays a significant role in generation and propagation of magnetohydrodynamic (MHD) waves. Until now, however, the global distribution of the Alfvén velocity in the magnetosphere has not been reported. To determine the spatial distribution of the Alfvén velocity, we have statistically examined the THEMIS magnetic field and electron density data obtained in the L (the equatorial geocentric distance to the field line measured in Earth’s radii) range of ~ 4–12 and at all local times near the magnetic equator between − 5° and 5° in magnetic latitude for 2008–2014. We observed a pronounced dawn–dusk asymmetry in the equatorial Alfvén velocity calculated from the THEMIS magnetic field and density data. That is, the dawnside Alfvén velocity is higher than the duskside Alfvén velocity. This asymmetry is due to the duskside bulge in the plasmasphere. The radial profile of the Alfvén velocity shows an increasing function of L between L = 4 and 10 in the dusk sector, while a decreasing function in the dawn sector. By comparing these Alfvén velocity distributions along the local time and radial distance, we discuss the occurrence distribution and propagation of MHD waves in the outer magnetosphere.http://link.springer.com/article/10.1186/s40623-018-0947-9Equatorial Alfvén velocityDawn–dusk asymmetry in the equatorial Alfvén velocityPlasmaspheric bulgeMHD waves |
| spellingShingle | Khan-Hyuk Kim Gi-Jeong Kim Hyuck-Jin Kwon Distribution of equatorial Alfvén velocity in the magnetosphere: a statistical analysis of THEMIS observations Earth, Planets and Space Equatorial Alfvén velocity Dawn–dusk asymmetry in the equatorial Alfvén velocity Plasmaspheric bulge MHD waves |
| title | Distribution of equatorial Alfvén velocity in the magnetosphere: a statistical analysis of THEMIS observations |
| title_full | Distribution of equatorial Alfvén velocity in the magnetosphere: a statistical analysis of THEMIS observations |
| title_fullStr | Distribution of equatorial Alfvén velocity in the magnetosphere: a statistical analysis of THEMIS observations |
| title_full_unstemmed | Distribution of equatorial Alfvén velocity in the magnetosphere: a statistical analysis of THEMIS observations |
| title_short | Distribution of equatorial Alfvén velocity in the magnetosphere: a statistical analysis of THEMIS observations |
| title_sort | distribution of equatorial alfven velocity in the magnetosphere a statistical analysis of themis observations |
| topic | Equatorial Alfvén velocity Dawn–dusk asymmetry in the equatorial Alfvén velocity Plasmaspheric bulge MHD waves |
| url | http://link.springer.com/article/10.1186/s40623-018-0947-9 |
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