DOI: 10.1029/2018JA025264
Scopus记录号: 2-s2.0-85047644607
论文题名: Observation of Ionospheric Alfvén Resonances at 1–30 Hz and Their Superposition With the Schumann Resonances
作者: Beggan C.D. ; Musur M.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 5 起始页码: 4202
结束页码: 4214
语种: 英语
英文关键词: ionosphere
; ionospheric Alfvén resonances
; magnetic field
; pulsations
; Schumann resonaces
英文摘要: Long-term measurements of the high-frequency magnetic field (0.1–100 Hz) have been made at Eskdalemuir Observatory in the United Kingdom since September 2012. We analyze five years of dynamic spectrograms to examine the occurrence and behavior of the Schumann and ionospheric Alfvén resonances (IAR) and Pc1 pulsations. The resonances, observed as diffuse bands, arise from reflections of energy both within the Earth-ionosphere cavity and from the nonlinear conductivity gradient of the ionosphere. Schumann Resonances (SR) occur continuously but IAR are observed to arise at local nighttime in ∼50% of days in the data set. Typically, IAR are found at frequencies of 1–8 Hz, but we find them extending out to 30 Hz and strongly superimposing over the first three Schumann resonances around 9% of the time. These phenomena include constructive and destructive interference, nonlinear frequency changes over the span of several hours, and polarity enhancements. In addition, the magnitude of the IAR does not decline rapidly with frequency as often proposed. We find that the IAR and their superposition with SR are strongly controlled by season and geomagnetic activity. We compare 6 days with the most unusual IAR behavior in the data set to ionosonde measurements of f0F2, a proxy for ionospheric conductivity but find little correlation. We suggest that, as current theoretical modeling does not account for these observations, further work is needed to understand how they arise. © 2018 Crown copyright. Journal of Geophysical Research: Space Physics © 2018 American Geophysical Union. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114039
Appears in Collections: 气候减缓与适应
There are no files associated with this item.
作者单位: British Geological Survey, Edinburgh, United Kingdom
Recommended Citation:
Beggan C.D.,Musur M.. Observation of Ionospheric Alfvén Resonances at 1–30 Hz and Their Superposition With the Schumann Resonances[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(5)