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|Title:||Evidence for transient, local ion foreshocks caused by dayside magnetopause reconnection|
Milan, Steve E.
von Alfthan, Sebastian
|Publisher:||European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)|
|Citation:||Annales Geophysicae, 2016, 34 (11), pp. 943-959 (17)|
|Abstract:||We present a scenario resulting in time-dependent behaviour of the bow shock and transient, local ion reflection under unchanging solar wind conditions. Dayside magnetopause reconnection produces flux transfer events driving fast-mode wave fronts in the magnetosheath. These fronts push out the bow shock surface due to their increased downstream pressure. The resulting bow shock deformations lead to a configuration favourable to localized ion reflection and thus the formation of transient, travelling foreshock-like field-aligned ion beams. This is identified in two-dimensional global magnetospheric hybrid-Vlasov simulations of the Earth's magnetosphere performed using the Vlasiator model (http://vlasiator.fmi.fi). We also present observational data showing the occurrence of dayside reconnection and flux transfer events at the same time as Geotail observations of transient foreshock-like field-aligned ion beams. The spacecraft is located well upstream of the foreshock edge and the bow shock, during a steady southward interplanetary magnetic field and in the absence of any solar wind or interplanetary magnetic field perturbations. This indicates the formation of such localized ion foreshocks.|
|Rights:||Copyright © the authors, 2016. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.|
|Description:||The simulation dataset is available on request from the Vlasiator team (http://vlasiator.fmi.fi, von Alfthan et al., 2014). IMAGE magnetometer data are available from http: //www.space.fmi.fi/image (Tanskanen, 2009). The AACGM software is available from http://engineering.dartmouth.edu/ superdarn/aacgm.html (Shepherd, 2014). The SuperDARN data can be accessed from the SuperDARN data portal hosted by Virginia Tech at http://vt.superdarn.org (Greenwald et al., 1995). The Supplement related to this article is available online at doi:10.5194/angeo-34-943-2016-supplement.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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