It has been suggested that ion foreshock waves originating in the solar wind upstream of the quasi-parallel (Q-||) shock can impact the planetary magnetosphere leading to standing shear Alfvén waves, i.e., the field line resonances (FLRs). In this paper, we carry out simulations of interaction between the solar wind and terrestrial magnetosphere under radial interplanetary magnetic field conditions by using a 3-D global hybrid model, and show the properties of self-consistently generated field line resonances through direct mode conversion in magnetospheric response to the foreshock disturbances for the first time. The simulation results show that the foreshock disturbances from the Q-|| shock can excite magnetospheric ultralow-frequency waves, among which the toroidal Alfvén waves are examined. It is found that the foreshock wave spectrum covers a wide frequency range and matches the band of FLR harmonics after excluding the Doppler shift effects. The fundamental harmonic of field line resonances dominates and has the strongest wave power, and the higher the harmonic order, the weaker the corresponding wave power. The nodes and anti-nodes of the odd and even harmonics in the equatorial plane are also presented. In addition, as the local Alfvén speed increases earthward, the corresponding frequency of each harmonic increases. The field-aligned current in the cusp region indicative of the possibly observable aurora is found to be a result of magnetopause perturbation which is caused by the foreshock disturbances, and a global view substantiating this scenario is given. Finally, it is found that when the solar wind Mach number decreases, the strength of both field line resonance and field-aligned current decreases accordingly.

有人提出，起源于准平行 ( Q -||) 激波上游的太阳风的离子前激波可以影响行星磁层，导致驻切阿尔文波，即场线共振 (FLR)。在本文中，我们通过使用 3-D 全局混合模型对径向行星际磁场条件下太阳风与地球磁层之间的相互作用进行了模拟，并展示了通过直接模式转换自洽产生的场线共振的特性。磁层对前震扰动的首次响应。仿真结果表明，来自Q的前震扰动-|| 激波可以激发磁层超低频波，其中检测了环形阿尔文波。发现前震波谱覆盖较宽的频率范围，在排除多普勒频移效应后与FLR谐波频带相匹配。场线谐振的基波占主导地位，具有最强的波功率，谐波阶数越高，对应的波功率越弱。还给出了赤道平面奇次谐波和偶次谐波的节点和波腹。此外，随着当地阿尔文速度向地球增加，每个谐波的相应频率增加。表明可能观测到极光的尖峰区域中的场对齐电流被发现是由前震扰动引起的磁层顶扰动的结果，并给出了证实这种情况的全局视图。最后发现，当太阳风马赫数减小时，场线共振强度和场准电流强度均相应减小。