DOI: 10.1002/2017JA024955
Scopus记录号: 2-s2.0-85047533409
论文题名: Low-Altitude Ion Heating, Downflowing Ions, and BBELF Waves in the Return Current Region
作者: Shen Y. ; Knudsen D.J. ; Burchill J.K. ; Howarth A.D. ; Yau A.W. ; Miles D.M. ; James H.G. ; Perry G.W. ; Cogger L.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 4 起始页码: 3087
结束页码: 3110
语种: 英语
英文关键词: auroral currents
; auroral ionosphere
; auroral particle acceleration
; field-aligned currents
; ion upflow and downflow
; wave/particle interaction
英文摘要: Heavy (O+) ion energization and field-aligned motion in and near the ionosphere are still not well understood. Based on observations from the CAScade, Smallsat and IOnospheric Polar Explorer (CASSIOPE) Enhanced Polar Outflow Probe at altitudes between 325 km and 730 km over 1 year, we present a statistical study (24 events) of ion heating and its relation to field-aligned ion bulk flow velocity, low-frequency waves, and field-aligned currents. The ion temperature and field-aligned bulk flow velocity are derived from 2-D ion velocity distribution functions measured by the suprathermal electron imager (SEI) instrument. Consistent ion heating and flow velocity characteristics are observed from both the SEI and the rapid-scanning ion mass spectrometer instruments. We find that transverse O+ ion heating in the ionosphere can be intense (up to 4.5 eV), confined to very narrow regions (∼2 km across B), is more likely to occur in the downward current region and is associated with broadband extremely low frequency (BBELF) waves. These waves are interpreted as linearly polarized perpendicular to the magnetic field. The amount of ion heating cannot be explained by frictional heating, and the correlation of ion heating with BBELF waves suggests that significant wave-ion heating is occurring and even dominating at altitudes as low as 350 km, a boundary that is lower than previously reported. Surprisingly, the majority of these heating events (17 out 24) are associated with core ion downflows rather than upflows. This may be explained by a downward pointing electric field in the low-altitude return current region. ©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/114231
Appears in Collections: 气候减缓与适应
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作者单位: Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada; Department of Physics and Astronomy, University of Iowa, Iowa City, IA, United States
Recommended Citation:
Shen Y.,Knudsen D.J.,Burchill J.K.,et al. Low-Altitude Ion Heating, Downflowing Ions, and BBELF Waves in the Return Current Region[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(4)