Open AccessJournal Article
Excitation and decay of solar-wind driven flows in the magnetosphere-ionosphere system
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In this paper, the authors considered the high-latitude ionospheric flows and their excitation and decay and proposed a flow-free equilibrium configuration for a magnetosphere which contains a given (arbitrary) amount of open flux.Abstract:
Basic concepts of the form of high-latitude ionospheric flows and their excitation and decay are discussed in the light of recent high time-resolution measurements made by ground-based radars. It is first pointed out that it is in principle impossible to adequately parameterize these flows by any single quantity derived from concurrent interplanetary conditions. Rather, even at its simplest, the flow must be considered to consist of two basic time-dependent components. The first is the flow driven by magnetopause coupling processes alone, principally by dayside reconnection. These flows may indeed be reasonably parameterized in terms of concurrent near-Earth interplanetary conditions, principally by the interplanetary magnetic field (IMF) vector. The second is the flow driven by tail reconnection alone. As a first approximation these flows may also be parameterized in terms of interplanetary conditions, principally the north-south component of the IMF, but with a delay in the flow response of around 30-60 min relative to the IMF. A delay in the tail response of this order must be present due to the finite speed of information propagation in the system, and we show how "growth" and "decay" of the field and flow configuration then follow as natural consequences. To discuss the excitation and decay of the two reconnection-driven components of the flow we introduce that concept of a flow-free equilibrium configuration for a magnetosphere which contains a given (arbitrary) amount of open flux. Reconnection events act either to create or destroy open flux, thus causing departures of the system from the equilibrium configuration. Flow is then excited which moves the system back towards equilibrium with the changed amount of open flux. We estimate that the overall time scale associated with the excitation and decay of the flow is about 15 min. The response of the system to both impulsive (flux transfer event) and continuous reconnection is discussed in these terms.read more
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Journal ArticleDOI
Estimating drift velocity of polar cap patches with all-sky airglow imager at Resolute Bay, Canada
TL;DR: In this paper, the authors presented an event of polar cap patches drifting anti-sunward during the southward IMF conditions at Resolute Bay, Canada (74.73°N, 265.07°E; AACGM latitude 82.9°).
Journal ArticleDOI
Superposed epoch analysis of the ionospheric convection evolution during substorms : onset latitude dependence
TL;DR: In this article, the ionospheric con- vection response to magnetospheric substorms was investigated using data from the Super Dual Auroral Radar Network (SuperDARN).
Journal ArticleDOI
THEMIS observations of substorms on 26 February 2008 initiated by magnetotail reconnection
Zuyin Pu,Xiangning Chu,X. Cao,V. M. Mishin,Vassilis Angelopoulos,Jingxu Wang,Yong Wei,Qiugang Zong,Suiyan Fu,Lun Xie,Karl-Heinz Glassmeier,Karl-Heinz Glassmeier,H. U. Frey,Christopher T. Russell,Jiang Liu,J. P. McFadden,Davin Larson,Stephen B. Mende,Ian R. Mann,David G. Sibeck,L. A. Sapronova,M. V. Tolochko,T. I. Saifudinova,Zhonghua Yao,Xuejun Wang,Chijie Xiao,Xu-Zhi Zhou,H. Rème,E. Lucek +28 more
TL;DR: Angelopoulos et al. as discussed by the authors showed that a distinct auroral intensification occurred during the earliest stage of onset, about 1 to 2 min after midtail reconnection began, and a second, major intensification was next in the substorm onset sequence, followed by rapid and extensive poleward expansion.
Superposed epoch analysis of the ionospheric convection evolution during substorms: onset latitude dependence
TL;DR: In this paper, the ionospheric con- vection response to magnetospheric substorms was investigated using data from the Super Dual Auroral Radar Network (SuperDARN).
Journal ArticleDOI
Flow-aligned jets in the magnetospheric cusp: Results from the Geospace Environment Modeling Pilot program
TL;DR: In this article, an extended flight of the Airborne Ionospheric Observatory during the Geospace Environment Modeling (GEM) Pilot program on January 16, 1990, allowed continuous all-sky monitoring of the two-dimensional ionospheric footprint of the northward interplanetary magnetic field (IMF) cusp in several wavelengths.
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