DOI: 10.1029/2018JA025290
Scopus记录号: 2-s2.0-85046484072
论文题名: MHD Stability of Magnetotail Configurations With a Bz Hump
作者: Birn J. ; Merkin V.G. ; Sitnov M.I. ; Otto A.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 5 起始页码: 3477
结束页码: 3492
语种: 英语
英文关键词: hump configurations
; magnetotail stability
; MHD simulations
英文摘要: Using two-dimensional magnetohydrodynamic (MHD) simulations, we explore the stability of magnetotail configurations that include a local enhancement of Bz (a “Bz hump”). We demonstrate that hump configurations can become unstable within the constraints of ideal MHD, even when strict boundary conditions v = 0 are imposed at all boundaries, consistent with the constraints of the ideal MHD energy principle. Necessary conditions for instability are that the boundaries on the earthward and high-latitude sides are far enough away, that the background pressure, equivalent to the lobe pressure, is small enough, and that the Bz enhancement or entropy reduction is strong enough. The unstable evolution then bears strong similarity to the evolution of observed and simulated dipolarized flux bundles and dipolarization fronts, presumed or simulated to be the consequence of reconnection. The Bz humps, which for sufficiently low background pressure correspond to entropy depletions, move faster for lower background density and penetrate closer toward Earth when they are initiated closer to Earth or when the background pressure is lower, similar to 3-D low-entropy flux tubes, which are affected by ballooning-/interchange-type modes. ©2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/113954
Appears in Collections: 气候减缓与适应
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作者单位: Space Science Institute, Boulder, CO, United States; Los Alamos National Laboratory, Los Alamos, NM, United States; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States; University of Alaska Fairbanks, Fairbanks, AK, United States
Recommended Citation:
Birn J.,Merkin V.G.,Sitnov M.I.,et al. MHD Stability of Magnetotail Configurations With a Bz Hump[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(5)