火星感应磁层边界的等离子体不稳定性,如边界层处速度剪切激发的Kelvin-Helmholtz(K-H)不稳定性,对火星感应磁层结构和磁层离子输运过程具有重要的影响.本文利用Mars Atmosphere and Volatile EvolutioN(MAVEN)卫星搭载的Magnetometer(M...火星感应磁层边界的等离子体不稳定性,如边界层处速度剪切激发的Kelvin-Helmholtz(K-H)不稳定性,对火星感应磁层结构和磁层离子输运过程具有重要的影响.本文利用Mars Atmosphere and Volatile EvolutioN(MAVEN)卫星搭载的Magnetometer(MAG)和Super Thermal and Thermal Ion Composition(STATIC)仪器所提供的磁场和等离子数据,分析了2018年5月21日火星感应磁层边界处观测到的K-H不稳定性事件,发现在磁场、重离子通量、离子成分与密度、和离子速度上存在五个连续的准周期变化,估算K-H波的周期为~100 s,同时在其中两个K-H涡旋内发现了磁通量绳结构.磁通量绳的轴向方向与边界层法向准垂直,且其中的离子成分与涡旋内电离层等离子体成分接近,表明此处的磁通量绳有可能是在K-H波的发展过程中形成.磁通量绳的整体速度也远大于此处的离子逃逸速度,这可能导致重离子O^(+)和O_(2)^(+)从火星大气中快速逃逸.展开更多
The characteristics of magnetohydrodynamic fast wave propagation in the solar stratified atmosphere are studied by the ray tracing method. The propagation behaviour of the wavefronts is described in detail. A magnetic...The characteristics of magnetohydrodynamic fast wave propagation in the solar stratified atmosphere are studied by the ray tracing method. The propagation behaviour of the wavefronts is described in detail. A magnetic field incorporating the characteristics field spreading expected in flux tubes is used, which represents the main feature of an active region. Partly ionization is considered beside the stratified solar atmosphere consisting chromosphere, transition region and corona. The study may explain the characteristics in observations of Moreton and extraultraviolet image telescope （EIT） waves. The wavefront incurred by the disturbance initialized at the base of the transition region propagates fast initially due to strong magnetic field, and it slows down when arriving beyond the region of flux-tube. Meanwhile, the wave propagates in the corona with a more consistent speed, as seen in the observation of EIT waves. The speeds and propagated characteristics in chromosphere and corona of the wavefronts are in agreement with those observed in H~ Moreton and EIT waves, respectively.展开更多
文摘火星感应磁层边界的等离子体不稳定性,如边界层处速度剪切激发的Kelvin-Helmholtz(K-H)不稳定性,对火星感应磁层结构和磁层离子输运过程具有重要的影响.本文利用Mars Atmosphere and Volatile EvolutioN(MAVEN)卫星搭载的Magnetometer(MAG)和Super Thermal and Thermal Ion Composition(STATIC)仪器所提供的磁场和等离子数据,分析了2018年5月21日火星感应磁层边界处观测到的K-H不稳定性事件,发现在磁场、重离子通量、离子成分与密度、和离子速度上存在五个连续的准周期变化,估算K-H波的周期为~100 s,同时在其中两个K-H涡旋内发现了磁通量绳结构.磁通量绳的轴向方向与边界层法向准垂直,且其中的离子成分与涡旋内电离层等离子体成分接近,表明此处的磁通量绳有可能是在K-H波的发展过程中形成.磁通量绳的整体速度也远大于此处的离子逃逸速度,这可能导致重离子O^(+)和O_(2)^(+)从火星大气中快速逃逸.
基金Supported by the National Natural Science Foundation of China under Grant Nos 40274050 and 40336052, and the National Key Basic Research Special Foundation of China under Grant No G2000078405.
文摘The characteristics of magnetohydrodynamic fast wave propagation in the solar stratified atmosphere are studied by the ray tracing method. The propagation behaviour of the wavefronts is described in detail. A magnetic field incorporating the characteristics field spreading expected in flux tubes is used, which represents the main feature of an active region. Partly ionization is considered beside the stratified solar atmosphere consisting chromosphere, transition region and corona. The study may explain the characteristics in observations of Moreton and extraultraviolet image telescope （EIT） waves. The wavefront incurred by the disturbance initialized at the base of the transition region propagates fast initially due to strong magnetic field, and it slows down when arriving beyond the region of flux-tube. Meanwhile, the wave propagates in the corona with a more consistent speed, as seen in the observation of EIT waves. The speeds and propagated characteristics in chromosphere and corona of the wavefronts are in agreement with those observed in H~ Moreton and EIT waves, respectively.
