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dc.contributor.authorRussell, A. J.B.
dc.contributor.authorWright, A. N.
dc.contributor.authorStreltsov, A. V.
dc.identifier.citationRussell , A J B , Wright , A N & Streltsov , A V 2013 , ' Production of small-scale Alfvén waves by ionospheric depletion, nonlinear magnetosphere-ionosphere coupling and phase mixing ' , Journal of Geophysical Research: Space Physics , vol. 118 , no. 4 , pp. 1450-1460 .
dc.identifier.otherORCID: /0000-0002-9877-1457/work/58055382
dc.identifier.otherORCID: /0000-0001-5690-2351/work/139965441
dc.descriptionThe authors acknowledge the International Space Science Institute (Switzerland) for funding the program that inspired this work. AJBR is grateful to the Royal Commission for the Exhibition of 1851 for present support and acknowledges an STFC studentship that funded part of this work.en
dc.description.abstractRockets and satellites have previously observed small-scale Alfven waves inside large-scale downward field-aligned currents, and numerical simulations have associated their formation with self-consistent magnetosphere-ionosphere coupling. The origin of these waves was previously attributed to ionospheric feedback instability; however, we show that they arise in numerical experiments in which the instability is excluded. A new interpretation is proposed in which strong ionospheric depletion and associated current broadening (a nonlinear steepening/wave-breaking process) form magnetosphereionosphere waves inside a downward current region and these oscillations drive upgoing inertial Alfven waves in the overlying plasma. The resulting waves are governed by characteristic periods, which are a good match to previously observed periods for reasonable assumed conditions. Meanwhile, wavelengths perpendicular to the magnetic field initially map to an ionospheric scale comparable to the electron inertial length for the low-altitude magnetosphere, but become shorter with time due to frequency-based phase mixing of boundary waves (a new manifestation of phase mixing). Under suitable conditions, these could act as seeds for the ionospheric feedback instability.
dc.relation.ispartofJournal of Geophysical Research: Space Physicsen
dc.subjectMagnetosphere-ionosphere couplingen
dc.subjectSmall-scale Alfven wavesen
dc.subjectIonospheric depletionen
dc.subjectPhase mixingen
dc.subjectMagnetosphere-ionosphere wavesen
dc.subjectIonospheric feedback instabilityen
dc.subjectQuiet auroral arcsen
dc.subjectField-line resonancesen
dc.subjectDynamic magnetosphereen
dc.subjectElectric fieldsen
dc.subjectQC Physicsen
dc.subjectSpace and Planetary Scienceen
dc.titleProduction of small-scale Alfvén waves by ionospheric depletion, nonlinear magnetosphere-ionosphere coupling and phase mixingen
dc.typeJournal articleen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.contributor.institutionUniversity of St Andrews. Applied Mathematicsen
dc.description.statusPeer revieweden

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