【摘要】 本文研究太阳活动低年期间英国South Uist、Hawick和Aberystwyth三台站电离层电子总量的冬夜行为特性。法拉第旋转记录分析表明,中纬度电离层电子总量冬夜增长幅度和出现率同季节和台站纬度有关。文中详细考察了冬夜增长的发生时刻和持续时间的分布状况,电子总量冬夜极大值位置,冬夜电子总量W型特征面貌,冬夜增长的运动速度与方向等,发现电离层电子总量冬夜值和冬夜增长同地磁活动指数之间存在着负相关关系。对冬夜增长的机制,本文提出一种磁共轭电离迁移与等离子层电离库原理。指出在冬夏至期间,由于南北半球的太阳天顶角、日照时间、大气温度和电离密度的显著差别,在全球范围内依次于各地傍晚时分,发生一种从夏半球中纬度电离层沿高空磁力线并经等离子层电离库的调节,而朝向冬半球中纬度电离层共轭区的电离迁移和电离层贸易风,以此来解释电离层电子总量的夜间行为。更多还原

【Abstract】 Studies of the behavior of winter nighttime increases (WNI) in total electron content (TEC) of the ionosphere at three stations, South Uist, Hawick and Aberystwyth, U. K. during a period of low solar activity are presented. Analysis of Faraday rotation records shows that the nighttime increases in the ionospheric TEC at middle latitudes are a regular phenomenon in winter. The average amount and the percentage occurrence of nighttime increases are related to seasons and station latitudes. Detailed examination is made on the distribution of starting time and the duration of WNI, the maximum position of nighttime TEC, as well as the velocities and directions of motion of these increases, etc. The W-shaped features and an extraordinary negative correlation between the increases in TEC and geomagnetic activities have been found. For the mechanism of WNI, a principle of geomagnetically conjugate point transfer of ionization and the plasmaspheric reservoir has been proposed. It is suggested that during the solstitial periods there is an ionospheric trade wind in the local evening on a global scale successively from the mid-latitude ionosphere of summer hemisphere to its conjugate region of winter one along magnetic field line at high altitudes through an adjustment of immigration and drainage, owing to substantial differences in solar declinations and sunset times, hence the differences in the atmospheric temperatures and ionization concentrations between two hemispheres. Consequently, the nocturnal characteristics in the ionospheric TEC have been explained.更多还原