高速太阳风条件下日侧磁层顶磁通量传输事件的全球磁流体力学模拟结果

Global MHD Results of Flux Transfer Events at the Dayside Magnetopause under High Solar Wind Speed

利用全球磁流体力学模拟,研究了高速太阳风条件下日侧磁层顶的磁通量传输事件(FTE)发生率的空间分布.从模拟结果中得到了FTE信号,并且这些FTE信号的特征与观测结果基本一致.磁层顶上的10个取样点共观测到39个FTE信号.统计分析表明,越靠近翼侧则观测到的FTE信号越少.这一现象可能是磁鞘中太阳风速度分布差异导致的.

Using Global MHD model, the spatial distribution of Flux Transfer Events(FTE) at the dayside magnetopause under high solar wind speed is investigated. The solar wind conditions of this case are vsw = 1200 km·s^-1, nsw = 3 cm^-3, Bz =-8.3 nT, By = 8.3 nT and Bx = 0 nT.The simulation results virtually agree with those expected FTE signatures from observations, and bipolar signatures and related variations of number density, pressure and velocity are found. A total number of 39 FTE are observed by ten virtual probes which are spread over the magnetopause from y =-5 Re to y = 5 Re. 14 FTE are found when the probe is near to the noon. However, when the probe is located near y =-5 Re and y= 5 Re, the same number, 3, of FTE in both locations is found. Furthermore, 8 FTE are found when the probe is adjacent to y =-2.5 Re and 11 FTE are found near y = 2.5 Re. In a nutshell, the number of FTE decreases as the observed probes approach the flank of the magnetopause, which could be caused by the distribution of solar wind velocity in magnetosheath.