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dc.contributor.authorElsden, Thomas
dc.contributor.authorWright, Andrew
dc.identifier.citationElsden , T & Wright , A 2020 , ' Evolution of high-m poloidal Alfvén waves in a dipole magnetic field ' , Journal of Geophysical Research: Space Physics , vol. 125 , no. 8 , e2020JA028187 .
dc.identifier.otherPURE: 270051414
dc.identifier.otherPURE UUID: 4a9e6c18-a91e-4748-943c-edc07deb9f71
dc.identifier.otherScopus: 85089889289
dc.identifier.otherORCID: /0000-0002-9877-1457/work/80257617
dc.identifier.otherORCID: /0000-0002-1910-2010/work/80257965
dc.identifier.otherWOS: 000577125000069
dc.descriptionFunding: Leverhulme Trust. Grant Number: ECF‐2019‐155; UKRI Science and Technology Facilities Council (STFC) Grant Number: ST/N000609/1.en
dc.description.abstractWe investigate how initially high-m, poloidal Alfvén waves evolve using a numerical model solving the ideal, cold, linear magnetohydrodynamic (MHD) equations in a 2-D dipole coordinate system. The curved magnetic geometry provides a key difference between the poloidal and toroidal Alfvén frequencies of any one field line. A polarization rotation from poloidal toward toroidal predicted from the Cartesian box model theory still occurs but now with the waves following contours of Alfvén frequency, which moves the Alfvén wave across field lines. The structure of these contours depends on the harmonic mode along the field line and the equilibrium. We find that the amplitude peak of the poloidal mode moves significantly radially outward in time. When the typically observed azimuthal phase motion of such waves is included, hodograms show a polarization rotation from purely poloidal to a mixed poloidal/toroidal polarization at all locations. Such features could be used to help interpret satellite observations of Pc4-5 poloidal ultralow frequency (ULF) waves in Earth's magnetosphere.
dc.relation.ispartofJournal of Geophysical Research: Space Physicsen
dc.rightsCopyright © 2020 American Geophysical Union. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the final published version of the work, which was originally published at
dc.subjectAlfven wavesen
dc.subjectULF wavesen
dc.subjectGE Environmental Sciencesen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.subjectAquatic Scienceen
dc.subjectSoil Scienceen
dc.subjectWater Science and Technologyen
dc.subjectAtmospheric Scienceen
dc.subjectGeochemistry and Petrologyen
dc.subjectEarth-Surface Processesen
dc.subjectEarth and Planetary Sciences (miscellaneous)en
dc.subjectSpace and Planetary Scienceen
dc.titleEvolution of high-m poloidal Alfvén waves in a dipole magnetic fielden
dc.typeJournal articleen
dc.contributor.sponsorScience & Technology Facilities Councilen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.contributor.institutionUniversity of St Andrews. Applied Mathematicsen
dc.description.statusPeer revieweden

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