Alfven波在微电离大气中的衰减特性研究  

Attenuation of Alfven Waves in Weakly Ionized Near Earth Atmosphere

作　　者：刘元涛[1,2] 赵华[1] 李磊[1] 王劲东[1] 周斌[1] 冯永勇[1] 

机构地区：[1]中国科学院空间科学与应用研究中心,北京100190 [2]中国科学院研究生院,北京100049

出　　处：《空间科学学报》2011年第3期299-303,共5页Chinese Journal of Space Science

基　　金：中国科学院空间科学与应用研究中心创新项目资助

摘　　要：利用简单的偶极子地磁场模型以及大气电子密度和电导率模式,分析地面产生的磁扰动以Alfven波的模式传播到近地空间区域.这种地面的磁扰动可能干扰近地空间卫星对空间磁扰动的观测.通过对地面磁扰动Alfven波模式1000 km高度内的衰减情况进行模拟,认为在近地空间采用地磁偶极子模型是合理的.由于衰减随扰动频率的增大而急剧增强,分析还得到了近地卫星能够探测到地面磁扰动的最大频率.计算结果表明,Alfven波的衰减主要集中在高度50km以下,这个区域内的大气电导率极其微弱,使Alfven波的传播受到极大衰减.0.4Hz以下的Alfven波沿磁力线传播到1000 km高度后衰减结为原来扰动幅度的千分之一,因此频率在0.4 Hz以下的Alfven波可能会干扰低轨卫星探测磁场脉动.Alfven waves,produced on the ground by artificial or by soundstorm,propagating to the near-earth space along the geomagnetic field lines,would decay greatly with distance.A dipole geomagnetic field model in near earth space,plasma density and conductivity models derived from observational data are used in this study to investigate the attenuation of Alfven waves below 1000 km altitude by numerical simulation methods.The frequency that would be detected by magnetometer carried by satellite was also found.The result showed that：Alfven waves will decay sharply in the height of less than 50 km for the much weak electrical conductivity in this region：it is 0.4Hz Alfven waves,when transmitted to 1000 km,that becomes about one-thousandth of the original,so Alfven waves below 0.4Hz can be detected by LEO satellites.

关 键 词：ALFVEN波 磁脉动 微弱电离大气 

分 类 号：P353[天文地球—空间物理学]