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Solar cycle variation of plasma mass density in the outer magnetosphere: Magnetoseismic analysis of toroidal standing Alfven waves detected by Geotail


Metadata FieldValueLanguage
dc.contributorKyungguk Min, kmin@auburn.eduen_US
dc.creatorTakahashi, Kazue
dc.creatorDenton, Richard E.
dc.creatorHirahara, Masafumi
dc.creatorMin, Kyungguk
dc.creatorOhtani, Shin-ichi
dc.creatorSanchez, Ennio
dc.date.accessioned2020-06-05T19:36:30Z
dc.date.available2020-06-05T19:36:30Z
dc.date.created2014-10
dc.identifier10.1002/2014JA020274en_US
dc.identifier.urihttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JA020274en_US
dc.identifier.urihttp://hdl.handle.net/11200/49859
dc.description.abstractWe study the variation of plasma mass density in the outer magnetosphere over a solar cycle using mass density estimated from the frequency of fundamental toroidal standing Alfven waves observed by the Geotail spacecraft. We identify wave events using ion bulk velocity data covering 1995-2006 and use events in the 0400-0800 magnetic local time sector for statistical analysis. We find that the F-10.7 index is a dominant controlling factor of the mass density. For the equatorial mass density rho(*)(eq) that is normalized to the value at L = 11, we obtain an empirical formula log rho(*)(eq)= -0.136 + 1.78 x 10(-3) = 10(-3) F-10.7, where the units of rho(*)(eq) and F-10.7 are amu cm(-3) and solar flux units (sfu; 1 sfu =10(-22) W m(-2) Hz(-1)), respectively. This formula indicates that rho(*)(eq) changes by a factor of 1.8, if F-10.7 changes from 70 sfu (solar minimum) to 210 sfu (solar maximum). A formula derived in a similar manner using GOES magnetometer data indicates that, for the same range of F-10.7, the mass density at L approximate to 7 varies by a factor of 4.1 We attribute the smaller factor at L = 11 to the lower O+/H+ number density ratio at higher L, the stronger F-10.7 dependence of the O+ outflow rate than the H+ outflow rate, and entry of solar wind H+ ions to the outer magnetosphere.en_US
dc.formatPDFen_US
dc.publisherAMER GEOPHYSICAL UNIONen_US
dc.relation.ispartofJOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICSen_US
dc.relation.ispartofseries2169-9380en_US
dc.subjectmass density; outer magnetosphere; magnetoseismology; solar cycle variation; ion compositionen_US
dc.subjectION COMPOSITION; WIND; TRANSPORT; BOUNDARY; DEPENDENCE; OUTFLOW; MODEL; COLDen_US
dc.titleSolar cycle variation of plasma mass density in the outer magnetosphere: Magnetoseismic analysis of toroidal standing Alfven waves detected by Geotailen_US
dc.typeTexten_US
dc.type.genreJournal Article, Academic Journalen_US
dc.citation.volume119en_US
dc.citation.issue10en_US
dc.citation.spage8338en_US
dc.citation.epage8356en_US
dc.description.statusPublisheden_US
dc.creator.orcid0000-0002-2095-8529en_US

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