Effects of the solar wind and the solar EUV flux on O+ escape rates from Venus

doi:10.1016/j.icarus.2018.11.017

CORC > 地质与地球物理研究所 > 中国科学院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

	Effects of the solar wind and the solar EUV flux on O+ escape rates from Venus
	Masunaga, K.1; Futaana, Y.1; Persson, M.1; Barabash, S.1; Zhang, T. L.2; Bong, Z. J.3,4; Fedorov, A.5
刊名	ICARUS
	2019-03-15
卷号	321 页码:379-387
关键词	Venus Ion escape Solar wind Solar EUV flux
ISSN号	0019-1035
DOI	10.1016/j.icarus.2018.11.017
英文摘要	We investigate dependences of O+ escape rates from Venus both on the solar wind and the solar extreme ultraviolet (EUV) flux by using the 8.5-year dataset (May 2006 to December 2014) of the Ion Mass Analyzer and the magnetometer aboard Venus Express. We examine the O+ escape rates for 8 different conditions depending on the solar winds dynamic pressure, the magnitude of the motional electric field, and the solar F10.7 index which is a good indicator for the solar EUV flux. We find that the O+ escape rates are mainly controlled by the motional electric field and the solar EUV flux in the magnetosheath. We suggest that the ion pickup by the motional electric field is the main ion escape process in the magnetosheath. On the other hand, in the induced magnetosphere, the O+ escape rates are controlled by not only the solar wind and the solar EUV flux but also return flows. We find that the return flows become dominant in the magnetotail in the solar maximum period, which results in reducing the net escape rates in the induced magnetosphere. As a result, net escape rates tend to become larger in the solar minimum period than those in the solar maximum period. Further analysis of the magnetic field shows that the return flows are preferably observed when the magnetic field component along the Venus-Sun line reverses multiple times in the magnetotail. We suggest that ionospheric irregular structures or IMF sector boundary crossings form the fine scale anti-parallel draping pattern of the interplanetary magnetic field (IMF), and this causes ion acceleration towards Venus due to the magnetic tension force or magnetic reconnections. Another possibility is precipitations of O+ pickup ions on the nightside of Venus under the fine structure of IMF. Since the return flows significantly affect the O+ escape rates from Venus, it is important to study not only long-term transition of ion outflow from Venus but also return flows to estimate the net ion loss from Venus over the long history of the solar system.
资助项目	Swedish Research Council[2015-04187]
WOS关键词	MAGNETIC-FIELD ; PLASMA ENVIRONMENT ; FLAPPING MOTION ; IONS ; IONOSPHERE
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	ACADEMIC PRESS INC ELSEVIER SCIENCE
WOS记录号	WOS:000460367200031
资助机构	Swedish Research Council ; Swedish Research Council ; Swedish Research Council ; Swedish Research Council ; Swedish Research Council ; Swedish Research Council ; Swedish Research Council ; Swedish Research Council
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/90876]
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	Masunaga, K.
作者单位	1.Swedish Inst Space Phys, Box 812, S-98128 Kiruna, Sweden 2.Austrian Acad Sci, Space Res Inst, Graz, Austria 3.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earth & Planetary Phys, Beijing, Peoples R China 4.Univ Chinese Acad Sci, Coll Earth & Planetary Sci, Beijing, Peoples R China 5.IRAP, Toulouse, France
推荐引用方式 GB/T 7714	Masunaga, K.,Futaana, Y.,Persson, M.,et al. Effects of the solar wind and the solar EUV flux on O+ escape rates from Venus[J]. ICARUS,2019,321:379-387.
APA	Masunaga, K..,Futaana, Y..,Persson, M..,Barabash, S..,Zhang, T. L..,...&Fedorov, A..(2019).Effects of the solar wind and the solar EUV flux on O+ escape rates from Venus.ICARUS,321,379-387.
MLA	Masunaga, K.,et al."Effects of the solar wind and the solar EUV flux on O+ escape rates from Venus".ICARUS 321(2019):379-387.