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Magnetic reconnection during steady magnetospheric convection and other magnetospheric modes
journal contribution
posted on 2017-05-22, 13:45 authored by Benoit Hubert, Jean-Claude Gerard, Steve E. Milan, Stanley W. H. CowleyWe use remote sensing of the proton aurora with the IMAGE-FUV SI12 (Imager for Magnetopause to Aurora Global Exploration–Far Ultraviolet–Spectrographic Imaging at 121.8 nm) instrument and radar measurements of the ionospheric convection from the SuperDARN (Super Dual Aurora Radar Network) facility to estimate the open magnetic flux in the Earth's magnetosphere and the reconnection rates at the dayside magnetopause and in the magnetotail during intervals of steady magnetospheric convection (SMC). We find that SMC intervals occur with relatively high open magnetic flux (average ∼ 0.745 GWb, standard deviation ∼ 0.16 GWb), which is often found to be nearly steady, when the magnetic flux opening and closure rates approximately balance around 55 kV on average, with a standard deviation of 21 kV. We find that the residence timescale of open magnetic flux, defined as the ratio between the open magnetospheric flux and the flux closure rate, is roughly 4 h during SMCs. Interestingly, this number is approximately what can be deduced from the discussion of the length of the tail published by Dungey (1965), assuming a solar wind speed of ∼ 450 km s−1. We also infer an enhanced convection velocity in the tail, driving open magnetic flux to the nightside reconnection site. We compare our results with previously published studies in order to identify different magnetospheric modes. These are ordered by increasing open magnetic flux and reconnection rate as quiet conditions, SMCs, substorms (with an important overlap between these last two) and sawtooth intervals.
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Citation
Annales Geophysicae, 2017, 35 (3), pp. 505-524Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and AstronomyVersion
- VoR (Version of Record)
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Annales GeophysicaePublisher
European Geosciences Union (EGU) 1. Copernicus Publications 2. Springer Verlagissn
0992-7689eissn
1432-0576Acceptance date
2017-02-23Copyright date
2017Available date
2017-05-22Publisher DOI
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http://www.ann-geophys.net/35/505/2017/Language
enAdministrator link
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Science & TechnologyPhysical SciencesAstronomy & AstrophysicsGeosciences, MultidisciplinaryMeteorology & Atmospheric SciencesGeologyMagnetospheric physics (auroral phenomena; magnetospheric configuration and dynamics; solar wind-magnetosphereinteractions)NEAR-EARTH MAGNETOTAILSOLAR-WINDIMAGE-FUVFLUX CONTENTSUBSTORMIONOSPHEREEXCITATIONSPACECRAFTSYSTEMDRIVEN
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