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Title: Evidence for transient, local ion foreshocks caused by dayside magnetopause reconnection
Authors: Pfau-Kempf, Yann
Hietala, Heli
Milan, Steve E.
Juusola, Liisa
Hoilijoki, Sanni
Ganse, Urs
von Alfthan, Sebastian
Palmroth, Minna
First Published: 4-Nov-2016
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 ( 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.
DOI Link: 10.5194/angeo-34-943-2016
ISSN: 0992-7689
eISSN: 1432-0576
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © the authors, 2016. This is an open-access article distributed under the terms of the Creative Commons Attribution License (, 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 (, von Alfthan et al., 2014). IMAGE magnetometer data are available from http: // (Tanskanen, 2009). The AACGM software is available from superdarn/aacgm.html (Shepherd, 2014). The SuperDARN data can be accessed from the SuperDARN data portal hosted by Virginia Tech at (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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