DOI: 10.1029/2018JA025487
Scopus记录号: 2-s2.0-85052393949
论文题名: Cross-Phase Determination of Ultralow Frequency Wave Harmonic Frequencies and Their Associated Plasma Mass Density Distributions
作者: Wharton S.J. ; Wright D.M. ; Yeoman T.K. ; James M.K. ; Sandhu J.K.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 8 起始页码: 6231
结束页码: 6250
语种: 英语
英文关键词: ground magnetometers
; magnetoseismology
; plasma density
; ultralow frequency waves
英文摘要: Latitudinally spaced ground-based magnetometers can be used to estimate the eigenfrequencies of magnetic field lines using the cross-phase technique. These eigenfrequencies can be used with a magnetic field model and an assumed plasma mass density distribution to determine the plasma mass density in the magnetosphere. Automating this process can be difficult, and so far, it has not been possible to distinguish between the different harmonics. Misidentification of the harmonic mode will lead to incorrect estimations of the plasma mass density. We have developed an algorithm capable of identifying multiple harmonics in cross-phase spectrograms, using International Monitor for Auroral Geomagnetic Effects magnetometers. Knowledge of multiple harmonics allows the distribution of plasma mass density to be estimated instead of assumed. A statistical study was performed that showed clear common bands of eigenfrequencies, interpreted as different harmonics. These eigenfrequencies were lowest in the early afternoon and at higher latitudes. There was also a greater occurrence of measurements in the dayside. We then modeled the plasma mass density distribution with a power law characterized by the exponent p and compared the model eigenfrequencies to the data. This suggested that the even modes did not form during the interval of this study. Examination of the harmonic spacing and the high occurrence of the third harmonic supported this suggestion. We attribute the absence of the even modes to the driving mechanisms. Finally, we show that an equatorial bulge in plasma mass density was not present in our study. ©2018. The Authors. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/113298
Appears in Collections: 气候减缓与适应
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作者单位: University of Leicester, Leicester, United Kingdom; Mullard Space Science Laboratory, Dorking, United Kingdom
Recommended Citation:
Wharton S.J.,Wright D.M.,Yeoman T.K.,et al. Cross-Phase Determination of Ultralow Frequency Wave Harmonic Frequencies and Their Associated Plasma Mass Density Distributions[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(8)