Evidence for transient, local ion foreshocks caused by dayside magnetopause reconnection
Ganse U; Pfau-Kempf Y; Hietala H; Juusola L; Palmroth M; Milan SE; von Alfthan S; Hoilijoki S
Evidence for transient, local ion foreshocks caused by dayside magnetopause reconnection
Ganse U
Pfau-Kempf Y
Hietala H
Juusola L
Palmroth M
Milan SE
von Alfthan S
Hoilijoki S
COPERNICUS GESELLSCHAFT MBH
Julkaisun pysyvä osoite on:
https://urn.fi/URN:NBN:fi-fe2021042716116
https://urn.fi/URN:NBN:fi-fe2021042716116
Tiivistelmä
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 fore-shock 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.
Kokoelmat
- Rinnakkaistallenteet [19207]