行星弓激波是行星空间环境与太阳风相互作用区域的最外层边界，其大小和形状能够影响行星空间系统与太阳风之间的物质、动量和能量的传输。大量的卫星观测数据显示，现有的各种弓激波模型和理论在描述和解释行星际磁场（IMF）对行星弓激波位形的控制机制时都遇到了瓶颈。金星弓激波代表了弱磁行星与太阳风相互作用形成的弓激波类型，其位形能更明显的体现出IMF的控制效应。本项目拟利用“金星快车”的观测数据和三维全球混杂模拟程序，研究IMF对金星弓激波位形的控制作用和物理机制。首先通过对3000多个卫星穿越弓激波事件进行统计分析，构建金星弓激波模型，提取IMF的方向和强度对金星弓激波的大小和不对称性的影响。然后利用混杂程序模拟卫星观测到的现象，通过对模拟结果进行定量地分析和论证，揭示IMF控制金星弓激波位形的主要机制。最后，尝试找出普遍存在于行星弓激波位形的垂直—平行不对称的物理原因。

Planetary bow shocks are the outmost boundaries where the planets interact with solar wind. The sizes and shapes of the planetary bow shocks influence the transport of mass, momentum and energy between the solar wind and the planetary space environment. Numerous in-situ observations indicate that the present models and theories are insufficient to describe the interplanetary magnetic field (IMF) control of the locations of planetary bow shocks. The Venus-like bow shock is defined as a bow shock that forms in front of a planet that has no intrinsic magnetic field, and the IMF influence is easier to be discerned from Venusian bow shock. This project will investigate the IMF control of the location of Venusian bow shock using the Venus Express (VEX) data and a three-dimensional global hybrid code. First, statistical analyses of the data set of about 3000 bow shock crossings will be carried out to construct a model of Venusian bow shock and extract the effects of the magnitude and orientation of the IMF on the size and asymmetries of Venusian bow shock. Then, the hybrid code will be used to simulate the observed phenomena and quantitatively analyze the mechanisms for the IMF control of the location of Venusian bow shock. Finally, we will try to find out the physical reason for the general perpendicular-parallel asymmetries in the locations of planetary bow shocks.