Influence of the IMF Cone Angle on Invariant Latitudes of Polar Region Footprints of FACs in the Magnetotail: Cluster Observation

	Influence of the IMF Cone Angle on Invariant Latitudes of Polar Region Footprints of FACs in the Magnetotail: Cluster Observation
	Cheng, Z. W.; Shi, J. K.; Zhang, J. C.; Torkar, K.; Kistler, L. M.; Dunlop, M.; Carr, C.; Reme, H.; Dandouras, I.; Fazakerley, A.
刊名	JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
	2018
卷号	123 期号:4 页码:2588-2597
关键词	Fac In Magnetotail FootprInts In Polar Region Imf Cone Angle
ISSN号	2169-9380
英文摘要	The influence of the interplanetary magnetic field (IMF) cone angle (the angle between the IMF direction and the Sun-Earth line) on the invariant latitudes of the footprints of the field-aligned currents (FACs) in the magnetotail has been investigated. We performed a statistical study of 542 FAC cases observed by the four Cluster spacecraft in the Northern Hemisphere. The results show that there are almost no FACs when the IMF cone angle is less than 10 degrees, and there are indications of the FACs in the plasma sheet boundary layers being weak under the radial IMF conditions. The footprints of the large FAC (> 10 nA/m(2)) cases are within invariant latitudes < 71 degrees and mainly within IMF cone angles theta > 60 degrees, which implies that the footprints of the large FACs mainly expand equatorward with large IMF cone angle. The equatorward boundary of the FAC footprints in the polar region decreases with increasing IMF cone angle (and has a better correlation for northward IMF), which shows that the IMF cone angle plays an important controlling role in FAC distributions in the magnetosphere-ionosphere coupling system. There is almost no correlation between the poleward boundary and the IMF cone angle for both northward and southward IMF. This is because the poleward boundary movement is limited by an enhanced lobe magnetic flux. This is the first time a correlation between FAC footprints in the polar region and IMF cone angles has been determined.
语种	英语
资助机构	National Natural Science Foundation of China [41474137, 41674145, 41374169] ; Specialized Research Fund for State Key Laboratories
内容类型	期刊论文
源URL	[http://ir.nssc.ac.cn/handle/122/6328]
专题	国家空间科学中心_空间科学部
通讯作者	Cheng, ZW (reprint author), NSSC CAS, State Key Lab Space Weather, Beijing, Peoples R China.
推荐引用方式 GB/T 7714	Cheng, Z. W.,Shi, J. K.,Zhang, J. C.,et al. Influence of the IMF Cone Angle on Invariant Latitudes of Polar Region Footprints of FACs in the Magnetotail: Cluster Observation[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,2018,123(4):2588-2597.
APA	Cheng, Z. W..,Shi, J. K..,Zhang, J. C..,Torkar, K..,Kistler, L. M..,...&Cheng, ZW .(2018).Influence of the IMF Cone Angle on Invariant Latitudes of Polar Region Footprints of FACs in the Magnetotail: Cluster Observation.JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,123(4),2588-2597.
MLA	Cheng, Z. W.,et al."Influence of the IMF Cone Angle on Invariant Latitudes of Polar Region Footprints of FACs in the Magnetotail: Cluster Observation".JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 123.4(2018):2588-2597.