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  2. 地质与地球物理研究所
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  4. 中国科学院地球与行星物理重点实验室
A Survey of Photoelectrons on the Nightside of Mars

文献类型：期刊论文

作者Cao, Y. -T.2; Cui, J.2,3; Wu, X. -S.3,5; Niu, D. -D.4; Lai, H. -R.2; Ni, B. -B.1,3; Luo, Q.1; Yu, J.2; Wei, Y.6
刊名GEOPHYSICAL RESEARCH LETTERS
出版日期2021-01-28
卷号48期号:2页码:8
ISSN号0094-8276
关键词Martian ionosphere MAVEN Photoelectrons
DOI10.1029/2020GL089998
英文摘要Despite produced exclusively on the dayside, photoelectrons, as an important population of the Martian ionosphere, have also been observed on the nightside. Here we present a statistical survey of nightside photoelectrons using the suprathermal electron measurements, made by the Solar Wind Electron Analyzer onboard the Mars Atmosphere and Volatile Evolution. We find that nearly 30% of the available nightside suprathermal electron spectra show clear photoelectron signatures. Nightside photoelectrons have an occurrence rate that decreases with increasing solar zenith angle and they are characterized by a preferentially field-aligned pitch angle distribution. Our analysis also suggests that nightside photoelectrons are less likely observed under the high solar wind condition. These observations are favorably interpreted by the scenario of photoelectron transport along cross-terminator magnetic field lines, as supported by a simplified test particle model. Our study highlights a complex plasma environment near Mars modulated by both internal and external conditions. Plain Language Summary Photoelectrons are an important population of a planetary upper atmosphere that plays a crucial role in ionization, heating, radiation, and escape. Despite that photoelectrons are ideally produced by solar radiation on the dayside only, they have also been observed on the nightside of a planet such as Mars. This study is devoted to a statistical survey of photoelectrons in the nightside Martian upper atmosphere, based on the state-of-the-art measurements made by the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. A surprisingly large fraction of photoelectron energy spectra is identified on the nightside of Mars, occupying nearly 30% of the available nightside measurements. Meanwhile, substantial variations in the observations of nightside photoelectrons are suggested by the data, revealing that (1) their occurrence rate declines rapidly near and beyond the terminator; (2) their velocities are more likely parallel to the ambient magnetic field lines; and (3) they are less likely observed under high solar wind dynamic pressures. These observations could be interpreted by photoelectron transport along large-scale magnetic field lines from their dayside source regions to the nightside, a scenario that is controlled by both internal and external conditions and thus provides a useful diagnostic of the ambient magnetic field configuration. Key Points . The photoelectron occurrence rate in the nightside Martian ionosphere decreases with increasing solar zenith angle Nightside photoelectrons are observed to be preferentially field-aligned, as a natural result of cross-terminator transport Nightside photoelectrons are more likely observed under low solar wind dynamical pressures
WOS关键词MAGNETIC-FIELD ; ENERGY PEAKS ; ELECTRONS ; MODEL
资助项目B-type Strategic Priority Program - Chinese Academy of Sciences (CAS)[XDB41000000] ; preresearch project on Civil Aerospace Technologies - China's National Space Administration[D020105] ; National Science Foundation of China[41525015] ; National Science Foundation of China[41525016] ; National Science Foundation of China[41774186] ; National Science Foundation of China[41904154] ; National Science Foundation of China[42030201] ; CAS Institute of Geology Geophysics[IGGCAS-201904]
WOS研究方向Geology
语种英语
出版者AMER GEOPHYSICAL UNION
WOS记录号WOS:000613648800054
资助机构B-type Strategic Priority Program - Chinese Academy of Sciences (CAS) ; B-type Strategic Priority Program - Chinese Academy of Sciences (CAS) ; preresearch project on Civil Aerospace Technologies - China's National Space Administration ; preresearch project on Civil Aerospace Technologies - China's National Space Administration ; National Science Foundation of China ; National Science Foundation of China ; CAS Institute of Geology Geophysics ; CAS Institute of Geology Geophysics ; B-type Strategic Priority Program - Chinese Academy of Sciences (CAS) ; B-type Strategic Priority Program - Chinese Academy of Sciences (CAS) ; preresearch project on Civil Aerospace Technologies - China's National Space Administration ; preresearch project on Civil Aerospace Technologies - China's National Space Administration ; National Science Foundation of China ; National Science Foundation of China ; CAS Institute of Geology Geophysics ; CAS Institute of Geology Geophysics ; B-type Strategic Priority Program - Chinese Academy of Sciences (CAS) ; B-type Strategic Priority Program - Chinese Academy of Sciences (CAS) ; preresearch project on Civil Aerospace Technologies - China's National Space Administration ; preresearch project on Civil Aerospace Technologies - China's National Space Administration ; National Science Foundation of China ; National Science Foundation of China ; CAS Institute of Geology Geophysics ; CAS Institute of Geology Geophysics ; B-type Strategic Priority Program - Chinese Academy of Sciences (CAS) ; B-type Strategic Priority Program - Chinese Academy of Sciences (CAS) ; preresearch project on Civil Aerospace Technologies - China's National Space Administration ; preresearch project on Civil Aerospace Technologies - China's National Space Administration ; National Science Foundation of China ; National Science Foundation of China ; CAS Institute of Geology Geophysics ; CAS Institute of Geology Geophysics
源URL[http://ir.iggcas.ac.cn/handle/132A11/100096]  
专题地质与地球物理研究所_中国科学院地球与行星物理重点实验室
通讯作者Cui, J.
作者单位1.Wuhan Univ, Sch Elect Informat, Dept Space Phys, Wuhan, Hubei, Peoples R China
2.Sun Yat Sen Univ, Sch Atmospher Sci, Zhuhai, Guangdong, Peoples R China
3.Chinese Acad Sci, Ctr Excellence Comparat Planetol, Hefei, Anhui, Peoples R China
4.Harbin Inst Technol, Inst Space Sci & Appl Technol, Shenzhen, Guangdong, Peoples R China
5.Chinese Acad Sci, Natl Astron Observ, Beijing, Peoples R China
6.Chinese Acad Sci, Inst Geol & Geophys, Beijing, Peoples R China
推荐引用方式
GB/T 7714		 Cao, Y. -T.,Cui, J.,Wu, X. -S.,et al. A Survey of Photoelectrons on the Nightside of Mars[J]. GEOPHYSICAL RESEARCH LETTERS,2021,48(2):8.
APA Cao, Y. -T..,Cui, J..,Wu, X. -S..,Niu, D. -D..,Lai, H. -R..,...&Wei, Y..(2021).A Survey of Photoelectrons on the Nightside of Mars.GEOPHYSICAL RESEARCH LETTERS,48(2),8.
MLA Cao, Y. -T.,et al."A Survey of Photoelectrons on the Nightside of Mars".GEOPHYSICAL RESEARCH LETTERS 48.2(2021):8.

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来源：地质与地球物理研究所

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