A comparison of Flux transfer events' motion determined by deHoffmann-Teller technique with the Cooling model

Abstract:

Flux transfer events (FTEs) are considered as a result of transient magnetic reconnection and are often observed in the vicinity of the Earth’s magnetopause. The FTEs are responsible for transfer of mass, energy and momentum between solar wind and magnetosphere. According to FTE generation models and in situ observations, FTEs are formed in the subsolar region when the interplanetary magnetic field (IMF) is southward while for northward IMF they should be formed in the polar cap regions. In the present study it is analyzed 58 FTE events observed by the THEMIS spacecraft. First of all, the deHoffmann-Teller technique is employed to determine the local FTE velocity and direction. Then, these parameters (velocity and direction) are compared with those predicted by the Cooling model which has largely been employed to estimate the motion of reconnected flux tubes over a modeled magnetopause under specific solar wind conditions. The calculated deHoffmann-Teller velocity and direction indicate that FTEs observed at the flanks of magnetosphere (|Y_GSM|≥10 Re) move antisunward and dawn/duskward. For intermediate longitudes (|Y_GSM|<10 Re) a combination of dusk/dawnward and southward motions is found for the present study. The comparison between the calculated FTEs' velocity/direction and those predicted by the Cooling model presents a good agreement. It is also found that 12 FTE events were observed in the equatorial region during northward IMF.