标题： 背景太阳风和阻力对日冕物质抛射驱动激波传播的影响 显示英文标题

标题： Effects of background solar wind and drag force on the propagation of coronal mass ejection driven shock

摘要： 行星际（IP）激波的传播，特别是由日冕物质抛射（CMEs）驱动的激波，仍然是日球物理和空间天气预报中的一个悬而未决的问题。 在这里，我们研究了周围太阳风对两个类似的由CME驱动的激波从太阳到地球传播的影响。 这两个激波事件（CME03：2010年4月3日和CME12：2012年7月12日）具有以下特性：两个事件（1）由晕状CME驱动（即源位置靠近太阳-地球线），（2）CME源位于南半球，（3）到地球的传播时间相似（约2天），（4）发生在非平静的太阳期间，（5）导致了严重的地磁暴。 根据日冕仪图像测量的初始（接近太阳）传播速度，CME03比CME12慢（约300 km/s），但两个事件到达地球所需的旅行时间大致相同。 根据Wind航天器的原位太阳风观测，CME03驱动的激波在激波上游的太阳风速度比CME12驱动的激波快。 这也在我们的全球MHD模拟中得到了证实。 我们模拟结果的分析表明，阻力力在激波传播中起着间接的重要作用。 本研究建议，除了太阳附近的初始CME传播速度、激波速度（惯性系中）以及周围的太阳风条件，特别是太阳风速度，是预测CME驱动激波事件到达时间的关键因素。 显示英文摘要

摘要： Propagation of interplanetary (IP) shocks, particularly those driven by coronal mass ejections (CMEs), is still an outstanding question in heliophysics and space weather forecasting. Here we address effects of the ambient solar wind on the propagation of two similar CME-driven shocks from the Sun to Earth. The two shock events (CME03: April 3, 2010 and CME12: July 12, 2012) have the following properties: Both events (1) were driven by a halo CME (i.e., source location is near the Sun-Earth line), (2) had a CME source in the southern hemisphere, (3) had a similar transit time (~2 days) to Earth, (4) occurred in a non-quiet solar period, and (5) led to a severe geomagnetic storm. The initial (near the Sun) propagation speed, as measured by coronagraph images, was slower (by ~300 km/s) for CME03 than CME12, but it took about the same amount of traveling time for both events to reach Earth. According to the in-situ solar wind observations from the Wind spacecraft, the CME03-driven shock was associated with a faster solar wind upstream of the shock than the CME12-driven shock. This is also demonstrated in our global MHD simulations. Analysis of our simulation result indicates that the drag force indirectly plays an important role in the shock propagation. The present study suggests that in addition to the initial CME propagation speed near the Sun the shock speed (in the inertial frame) and the ambient solar wind condition, in particular the solar wind speed, are the key to timing the arrival of CME-driven-shock events.