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
Reversed flow events in the winter cusp ionosphere observed by the European Incoherent Scatter (EISCAT) Svalbard radar
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The influence of IMF By on the nature of the nightside high-latitude ionospheric flow during intervals of positive IMF Bz
TL;DR: In this article, it was shown that flow bursts of a similar size and speed to those observed under BY negative (~1000m s-1, spanning 2-3h of MLT in the midnight sector) also occur when BY is positive.
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The location and rate of dayside reconnection during an interval of southward interplanetary magnetic field
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TL;DR: In this paper, the authors used ionospheric data from the SuperDARN radar network and a DMSP satellite to obtain a comprehensive description of the spatial and temporal pattern of day-side reconnection.
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Aurora and open magnetic flux during isolated substorms, sawteeth, and SMC events
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The dynamics and relationships of precipitation, temperature and convection boundaries in the dayside auroral ionosphere
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TL;DR: In this paper, a continuous band of high ion temperature, which persisted for about 8h and zigzagged north-south across more than five degrees in latitude in the dayside (07:00-15:00MLT) auroral ionosphere, was observed by the EISCAT VHF radar on 23 November 1999.
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