FTE signatures at the dayside magnetopause

Statistical studies reveal that FTEs observed on the flanks of the magnetosphere are equally common during periods of northward and southward IMF orientation. Since the events are attributed to reconnection along extended tilted lines passing through the subsolar magnetopause, a question arises as to why FTEs are so infrequently observed during periods of northward IMF orientation on the dayside magnetopause. We present an analytical model for the magnetic field perturbations generated by FTEs with elliptical cross sections moving slowly relative to flow velocities in the surrounding magnetosheath and magnetospheric media. Model results indicate that FTE perturbations in both regions diminish rapidly as the shear between the magnetosheath and magnetospheric magnetic fields decreases, and that the ratio of event amplitudes in the magnetosheath to those in the magnetosphere diminishes rapidly as the ratio of magnetospheric to magnetosheath magnetic field strengths increases. Consequently, magnetosheath events occurring for southward IMF orientations should dominate statistical surveys of the dayside magnetopause.