DOI: 10.1029/2017JA025067
Scopus记录号: 2-s2.0-85047648496
论文题名: Field-Aligned Currents in Saturn's Magnetosphere: Observations From the F-Ring Orbits
作者: Hunt G.J. ; Provan G. ; Bunce E.J. ; Cowley S.W.H. ; Dougherty M.K. ; Southwood D.J.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 5 起始页码: 3806
结束页码: 3821
语种: 英语
英文关键词: Cassini
; F-ring orbits
; field-aligned currents
; magnetosphere
; periodicities
; Saturn
英文摘要: We investigate the azimuthal magnetic field signatures associated with high-latitude field-aligned currents observed during Cassini's F-ring orbits (October 2016–April 2017). The overall ionospheric meridional current profiles in the northern and southern hemispheres, that is, the regions poleward and equatorward of the field-aligned currents, differ most from the 2008 observations. We discuss these differences in terms of the seasonal change between data sets and local time (LT) differences, as the 2008 data cover the nightside while the F-ring data cover the post-dawn and dusk sectors in the northern and southern hemispheres, respectively. The F-ring field-aligned currents typically have a similar four current sheet structure to those in 2008. We investigate the properties of the current sheets and show that the field-aligned currents in a hemisphere are modulated by that hemisphere's “planetary period oscillation” (PPO) systems. We separate the PPO-independent and PPO-related currents in both hemispheres using their opposite symmetry. The average PPO-independent currents peak at ~1.5 MA/rad just equatorward of the open closed field line boundary, similar to the 2008 observations. However, the PPO-related currents in both hemispheres are reduced by ~50% to ~0.4 MA/rad. This may be evidence of reduced PPO amplitudes, similar to the previously observed weaker equatorial oscillations at similar dayside LTs. We do not detect the PPO current systems' interhemispheric component, likely a result of the weaker PPO-related currents and their closure within the magnetosphere. We also do not detect previously proposed lower latitude discrete field-aligned currents that act to “turn off” the PPOs. ©2018. The Authors. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/113971
Appears in Collections: 气候减缓与适应
There are no files associated with this item.
作者单位: Blackett Laboratory, Imperial College London, London, United Kingdom; Department of Physics and Astronomy, University of Leicester, Leicester, United Kingdom
Recommended Citation:
Hunt G.J.,Provan G.,Bunce E.J.,et al. Field-Aligned Currents in Saturn's Magnetosphere: Observations From the F-Ring Orbits[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(5)