Van Allen Probes investigation of the large scale duskward electric field and its role in ring current formation and plasmasphere erosion in the June 1, 2013 storm

TitleVan Allen Probes investigation of the large scale duskward electric field and its role in ring current formation and plasmasphere erosion in the June 1, 2013 storm
Publication TypeJournal Article
Year of Publication2015
AuthorsThaller, SA, Wygant, JR, Dai, L, Breneman, AW, Kersten, K, Cattell, CA, Bonnell, JW, Fennell, JF, Gkioulidou, M, Kletzing, CA, De Pascuale, S, Hospodarsky, GB, Bounds, SR
JournalJournal of Geophysical Research: Space Physics
Date Published05/2015
Keywordselectric field; inner magnetosphere; plasma convection; plasmasphere; ring current; Van Allen Probes
AbstractUsing the Van Allen Probes we investigate the enhancement in the large scale duskward convection electric field during the geomagnetic storm (Dst ~ −120 nT) on June 1, 2013 and its role in ring current ion transport and energization, and plasmasphere erosion. During this storm, enhancements of ~1-2 mV/m in the duskward electric field in the co-rotating frame are observed down to L shells as low as ~2.3. A simple model consisting of a dipole magnetic field and constant, azimuthally westward, electric field is used to calculate the earthward and westward drift of 90° pitch angle ions. This model is applied to determine how far earthward ions can drift while remaining on Earth's night side, given the strength and duration of the convection electric field. The calculation based on this simple model indicates that the enhanced duskward electric field is of sufficient intensity and duration to transport ions from a range of initial locations and initial energies characteristic of (though not observed by the Van Allen Probes) the earthward edge of the plasma sheet during active times ( L ~ 6–10 and ~1-20 keV) to the observed location of the 58–267 keV ion population, chosen as representative of the ring current (L ~3.5 – 5.8). According to the model calculation, this transportation should be concurrent with an energization to the range observed, ~58-267 keV. Clear coincidence between the electric field enhancement and both plasmasphere erosion and ring current ion (58–267 keV) pressure enhancements are presented. We show for the first time, nearly simultaneous enhancements in the duskward convection electric field, plasmasphere erosion, and increased pressure of 58–267 keV ring current ions. These 58–267 keV ions have energies that are consistent with what they are expected to pick up by gradient B drifting across the electric field. These observations strongly suggest that we are observing the electric field that energizes the ions and produces the erosion of the plasmasphere.
URLhttp://doi.wiley.com/10.1002/2014JA020875
DOI10.1002/2014JA020875
Short TitleJ. Geophys. Res. Space Physics


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