远磁尾磁层顶位形的偏转

Deflection of Magnetopause in the Distant Magnetotail

利用WIND和ARTEMIS卫星观测数据,分析远磁尾磁层顶对行星际和太阳风变化的响应,尤其是偏离日地连线的太阳风速度改变对远磁尾磁层顶的影响.研究发现在2011年9月13日的事件中,P2卫星观测到高速且高密度的磁鞘流.利用最小变量法进行分析发现,磁层顶沿着偏离日地连线的太阳风速度方向发生偏转.根据相似三角形定理,推断出本次事件中磁层顶在y方向和z方向上的偏转幅度分别达到10R_e和6R_e.P1和P2卫星的相对位置也证实了这一观点.因此,偏离日地连线的太阳风速度对远磁尾磁层顶的位形影响很大.研究结果可为建立包含太阳风速度v_y和v_z效应的磁层顶模型提供观测证据.

The responses of the magnetopause in the distant magnetotail to the interplanetary and solar wind conditions, especially to the variation of the solar wind velocity, are studied by WIND and ARTEMIS data. It is found that the properties of sustaining dense high-speed flow were observed by P2 satellite in the magnetosphere on 13 September 2011, which suggests that the satellite passed through the magnetopause and entered the magnetosheath region. The data axe analyzed using the minimum variable method. The results show that the normal of the magnetopause is along the direction of the solar wind velocity. According to the similar triangular theorem, it can be deduced that the deflection scale of the magnetopause is about 10 Re and 6 Re in y and z direction respectively. And the relative position of the P1 and P2 satellites also confirmed this opinion. The analyses suggest that the magnetopause location and shape in this event are mainly affected by the solar wind speed in the distant magnetotail. The result can provide observational evidence for establishing the magnetopause model which includes the effects of the solar wind vy and vz.