Testing linear theory of EMIC waves in the inner magnetosphere: Cluster observations

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	Testing linear theory of EMIC waves in the inner magnetosphere: Cluster observations
	Lin, R. -L.; Zhang, J. -C.; Allen, R. C.; Kistler, L. M.; Mouikis, C. G.; Gong, J. -C.; Liu, S. -Q.; Shi, L. -Q.; Klecker, B.; Sauvaud, J. -A.; Dunlop, M. W.; Zhang, JC (reprint author), Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.
Department	空间环境部
Source Publication	JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
	2014
Volume	119 Issue:2 Pages:1004-1027
ISSN	2169-9380
Language	英语
Keyword	Magnetosphere Emic Waves Electron Density Cluster
Abstract	In this paper, we test whether time periods with hot proton temperature anisotropy are associated with electromagnetic ion cyclotron (EMIC) waves and whether the plasma conditions during the observed waves satisfy the linear theory threshold condition. We identify 865 events observed by the Composition Distribution Function instrument onboard Cluster spacecraft 4 during 1 January 2001 to 1 January 2011 that exhibit a positive temperature anisotropy (A(hp)=T-h/T-vertical bar h-1) in the 10-40keV protons. The events occur over an L range from 4 to 10 in all magnetic local times and at magnetic latitudes (MLATs) within 50 degrees. Of these hot proton temperature anisotropy (HPTA) events, only 68 events have electromagnetic ion cyclotron (EMIC) waves. In these 68 HPTA events, for those at 3.81.0 nT(2)/Hz mainly appear in the region with f(EMIC)/f(H,eq)<0.8. Two stop bands are present, one near the region with f(EMIC)/f(H,eq)approximate to 0.33, the other in the region with 0.8H bands satisfy A(hp)/(A(hp)+1)>f(EMIC)/f(H,lo), A(hp)/(A(hp)+1)>0.45xf(EMIC)/f(H,lo), and A(hp)/(A(hp)+1)<0.45xf(EMIC)/f(H,lo). f(EMIC), f(H,eq), and f(H,lo) are the EMIC wave frequency, the magnetic equatorial, and the local proton gyrofrequencies. We also find that the EMIC waves predominantly occur with A(hp)>0.25. By testing a threshold equation for the EMIC instability based on linear theory, we find that for EMIC waves with \|MLAT\|10 degrees in the He, H, and>H bands, the percentages that satisfy the predicted conditions for wave growth by the threshold equation are 15.2%, 24.6%, and 25.6%. For the EMIC waves with \|MLAT\|>10 degrees the percentages that satisfy the wave growth predicted conditions are only 2.8%, 2.6%, and 0.0%. Finally, possible reasons for the low forecast accuracies of EMIC waves are suggested. Key Points We do the statistical analysis of EMIC waves from a 10year Cluster observation We test the A_hp versus EMIC wave frequency formula of Kennel and Petschek (1966) We test the linear theory derived by Blum et al. (2009)
Indexed By	SCI
Funding Project	中国科学院空间科学与应用研究中心
Document Type	期刊论文
Identifier	http://ir.nssc.ac.cn/handle/122/2709
Collection	空间环境部
Corresponding Author	Zhang, JC (reprint author), Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.
Recommended Citation GB/T 7714	Lin, R. -L.,Zhang, J. -C.,Allen, R. C.,et al. Testing linear theory of EMIC waves in the inner magnetosphere: Cluster observations[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,2014,119(2):1004-1027.
APA	Lin, R. -L..,Zhang, J. -C..,Allen, R. C..,Kistler, L. M..,Mouikis, C. G..,...&Zhang, JC .(2014).Testing linear theory of EMIC waves in the inner magnetosphere: Cluster observations.JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS,119(2),1004-1027.
MLA	Lin, R. -L.,et al."Testing linear theory of EMIC waves in the inner magnetosphere: Cluster observations".JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 119.2(2014):1004-1027.

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