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DOI | 10.1029/2019GL081980 |
Magnetic Effects of Plasma Pressure Gradients in the Upper F Region | |
Laundal, K. M.; Hatch, S. M.; Moretto, T. | |
2019-03-16 | |
发表期刊 | GEOPHYSICAL RESEARCH LETTERS |
ISSN | 0094-8276 |
EISSN | 1944-8007 |
出版年 | 2019 |
卷号 | 46期号:5页码:2355-2363 |
文章类型 | Article |
语种 | 英语 |
国家 | Norway |
英文摘要 | The Swarm satellites fly at altitudes that at polar latitudes are generally assumed to only contain currents that are aligned with the local magnetic field. Therefore, disturbances along the main field direction are mainly signatures of auroral electrojet currents, with a relatively smooth structure due to the distance from the currents. Here we show that superimposed on this smooth signal is an irregular pattern of small perturbations, which are anticorrelated with the plasma density measured by the Langmuir probe. We show that the perturbations can be remarkably well reproduced by assuming they represent a jxB force, which balances the plasma pressure gradient implied by the density variations. The associated diamagnetic current, previously reported to be most important near the equator, appears to be a ubiquitous phenomenon also at polar latitudes. A spectral analysis indicates that this effect dominates magnetic field intensity variations at small-scale sizes of a few tens of kilometers. Plain Language Summary The Swarm satellites fly at altitudes that at polar latitudes are generally assumed to only contain currents that are aligned with the local magnetic field. Therefore, disturbances in the magnetic field strength are mainly signatures of horizontal currents below the satellites. Such disturbances have a smooth structure due to the distance from the currents. Here we show that superimposed on this smooth signal is an irregular pattern of small perturbations, which are anticorrelated with the local plasma density. We show that this anticorrelation can be explained in terms of pressure balance between particles and the magnetic field. The electric currents that are associated with the magnetic field fluctuations, diamagnetic currents, have previously been reported to be most important near the equator. Our results show that they are a ubiquitous phenomenon at all latitudes and indicate that the diamagnetic effect dominates magnetic field intensity variations at small-scale sizes of a few tens of kilometers. |
英文关键词 | polar ionosphere plasma density magnetic field fluctuations Swarm diamagnetic currents polar cap patch |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000462612900004 |
WOS关键词 | IONOSPHERIC CURRENTS ; CHAMP SATELLITE ; CURRENT SYSTEMS ; SWARM ; GRAVITY |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/181594 |
专题 | 气候变化 |
作者单位 | Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway |
推荐引用方式 GB/T 7714 | Laundal, K. M.,Hatch, S. M.,Moretto, T.. Magnetic Effects of Plasma Pressure Gradients in the Upper F Region[J]. GEOPHYSICAL RESEARCH LETTERS,2019,46(5):2355-2363. |
APA | Laundal, K. M.,Hatch, S. M.,&Moretto, T..(2019).Magnetic Effects of Plasma Pressure Gradients in the Upper F Region.GEOPHYSICAL RESEARCH LETTERS,46(5),2355-2363. |
MLA | Laundal, K. M.,et al."Magnetic Effects of Plasma Pressure Gradients in the Upper F Region".GEOPHYSICAL RESEARCH LETTERS 46.5(2019):2355-2363. |
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