The Effect of Solar Wind Mach Numbers on the Occurrence Rate of Flux Transfer Events at the Dayside Magnetopause

Abstract

AbstractAlthough many works have investigated the occurrence rate of flux transfer events (FTEs) under different upstream conditions, the relation between the upstream Mach number and the occurrence rate of FTEs remains unclear. By using global magnetohydrodynamics simulations, we study the occurrence rate of FTEs under different upstream Alvénic Mach numbers (MA). A recently developed method is used to identify the FTEs throughout the dayside magnetopause. It shows that the occurrence rate of FTEs decreases with increasing value of MA. We suggest that the magnetosheath β, which increases with increasing MA, plays an important role in the process of reconnection and thus affects the occurrence rate of FTEs. As the solar wind MA increases with increasing distance from the Sun, we speculate that the planet with a larger heliocentric distance may have less FTEs because of the increasing value of upstream MA.