Guo Jianpeng, Wei Fengsi, Feng Xueshang, Liu Huixin, Wan Weixing, Yang Zhiliang, Xu Jiyao, Liu Chaoxu
State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China.
Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, Fukuoka, 812-8581, Japan.
Sci Rep. 2016 Jan 5;6:18895. doi: 10.1038/srep18895.
Alfvén waves have been proposed as an important mechanism for the heating of the Sun's outer atmosphere and the acceleration of solar wind, but they are generally believed to have no significant impact on the Earth's upper atmosphere under quiet geomagnetic conditions due to their highly fluctuating nature of interplanetary magnetic field (i.e., intermittent southward magnetic field component). Here we report that a long-duration outward propagating Alfvén wave train carried by a high-speed stream produced continuous (~2 days) and strong (up to ± 40%) density disturbances in the Earth's thermosphere in a way by exciting multiple large-scale gravity waves in auroral regions. The observed ability of Alfvén waves to excite large-scale gravity waves, together with their proved ubiquity in the solar atmosphere and solar wind, suggests that Alfvén waves could be an important solar-interplanetary driver of the global thermospheric disturbances.
阿尔文波被认为是太阳外层大气加热和太阳风加速的重要机制，但由于行星际磁场的高度波动特性（即间歇性南向磁场分量），人们普遍认为在平静的地磁条件下，它们对地球高层大气没有显著影响。在此我们报告，高速流携带的长时间向外传播的阿尔文波列，通过在极光区域激发多个大尺度重力波，在地球热层中产生了持续约2天的强烈（高达±40%）密度扰动。观测到的阿尔文波激发大尺度重力波的能力，以及它们在太阳大气和太阳风中普遍存在的事实，表明阿尔文波可能是全球热层扰动的一个重要太阳-行星际驱动因素。
