DOI: 10.1029/2017JA025151
Scopus记录号: 2-s2.0-85047661538
论文题名: Ionizing Electrons on the Martian Nightside: Structure and Variability
作者: Lillis R.J. ; Mitchell D.L. ; Steckiewicz M. ; Brain D. ; Xu S. ; Weber T. ; Halekas J. ; Connerney J. ; Espley J. ; Benna M. ; Elrod M. ; Thiemann E. ; Eparvier F.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 5 起始页码: 4349
结束页码: 4363
语种: 英语
英文关键词: electron
; ionizing
; Mars
; nightside
; structure
; variability
英文摘要: The precipitation of suprathermal electrons is the dominant external source of energy deposition and ionization in the Martian nightside upper atmosphere and ionosphere. We investigate the spatial patterns and variability of ionizing electrons from 115 to 600 km altitude on the Martian nightside, using CO2 electron impact ionization frequency (EIIF) as our metric, examining more than 3 years of data collected in situ by the Mars Atmosphere and Volatile EvolutioN spacecraft. We characterize the behavior of EIIF with respect to altitude, solar zenith angle, solar wind pressure, and the geometry and strength of crustal magnetic fields. EIIF has a complex and correlated dependence on these factors, but we find that it generally increases with altitude and solar wind pressure, decreases with crustal magnetic field strength and does not depend detectably on solar zenith angle past 115°. The dependence is governed by (a) energy degradation and backscatter by collisions with atmospheric neutrals below ~220 km and (b) magnetic field topology that permits or retards electron access to certain regions. This field topology is dynamic and varies with solar wind conditions, allowing greater electron access at higher altitudes where crustal fields are weaker and also for higher solar wind pressures, which result in stronger draped magnetic fields that push closed crustal magnetic field loops to lower altitudes. This multidimensional electron flux behavior can in the future be parameterized in an empirical model for use as input to global simulations of the nightside upper atmosphere, which currently do not account for this important source of energy. ©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/114022
Appears in Collections: 气候减缓与适应
There are no files associated with this item.
作者单位: Space Sciences Laboratory, University of California Berkeley, Berkeley, CA, United States; IRAP, Université de Toulouse, CNRS, UPS, CNES, Toulouse, France; Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO, United States; Department of Physics and Astronomy, University of Iowa, Iowa City, IA, United States; NASA Goddard Space Flight Center, Greenbelt, MD, United States
Recommended Citation:
Lillis R.J.,Mitchell D.L.,Steckiewicz M.,et al. Ionizing Electrons on the Martian Nightside: Structure and Variability[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(5)