DOI: 10.1002/2017JA024420
Scopus记录号: 2-s2.0-85040220085
论文题名: An Empirical Orthogonal Function Reanalysis of the Northern Polar External and Induced Magnetic Field During Solar Cycle 23
作者: Shore R.M. ; Freeman M.P. ; Gjerloev J.W.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 1 起始页码: 781
结束页码: 795
语种: 英语
英文关键词: decomposition of variability
; disturbance polar equivalent current systems
; empirical orthogonal functions
; external magnetic field
; graph theory
; polar ionosphere
英文摘要: We apply the method of data-interpolating empirical orthogonal functions (EOFs) to ground-based magnetic vector data from the SuperMAG archive to produce a series of month length reanalyses of the surface external and induced magnetic field (SEIMF) in 110,000 km2 equal-area bins over the entire northern polar region at 5 min cadence over solar cycle 23, from 1997.0 to 2009.0. Each EOF reanalysis also decomposes the measured SEIMF variation into a hierarchy of spatiotemporal patterns which are ordered by their contribution to the monthly magnetic field variance. We find that the leading EOF patterns can each be (subjectively) interpreted as well-known SEIMF systems or their equivalent current systems. The relationship of the equivalent currents to the true current flow is not investigated. We track the leading SEIMF or equivalent current systems of similar type by intermonthly spatial correlation and apply graph theory to (objectively) group their appearance and relative importance throughout a solar cycle, revealing seasonal and solar cycle variation. In this way, we identify the spatiotemporal patterns that maximally contribute to SEIMF variability over a solar cycle. We propose this combination of EOF and graph theory as a powerful method for objectively defining and investigating the structure and variability of the SEIMF or their equivalent ionospheric currents for use in both geomagnetism and space weather applications. It is demonstrated here on solar cycle 23 but is extendable to any epoch with sufficient data coverage. ©2017. The Authors. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114817
Appears in Collections: 气候减缓与适应
There are no files associated with this item.
作者单位: British Antarctic Survey, Cambridge, United Kingdom; Applied Physics Laboratory, The Johns Hopkins University, Laurel, MD, United States; Birkeland Center of Excellence, Department of Physics and Technology, University of Bergen, Bergen, Norway
Recommended Citation:
Shore R.M.,Freeman M.P.,Gjerloev J.W.. An Empirical Orthogonal Function Reanalysis of the Northern Polar External and Induced Magnetic Field During Solar Cycle 23[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(1)