Reconstructed results based on actual observations under conditions of geomagnetic quiet and storm both show that variations of ionospheric electron density with height, latitude, longitude and time can be resolved by means of CIT with ground-based GPS network and occultation observations. 在平静日和磁暴期间两种条件下利用实测数据的重建结果表明，GPS地面台网和掩星观测结合的电离层层析可以获得电离层电子密度在高度-纬度-经度-时间四维空间中的变化。
The sea was quiet before the storm struck. 暴风雨来袭前海面很平静。
Immediately after that, Fengyun mutation substantial selling a sudden gush, until then people began to understand that, however, before the quiet before the storm are the illusion. 紧接着，风云突变，大量抛盘骤然涌出，直到这时人们才明白，原来之前的宁静不过是暴风雨前的假象。
Here I thought the situation was about to clear up, I hadn't anticipated that that was merely a quiet pause in the storm. 我还以为局势快明朗了，却不料是暴风雨来临前短暂一刻。
Based on the fundamental theory of natural alternating electromagnetic field, we have studied the varying characteristics of apparent resistivity during magnetically quiet day and magnetic storm. 基于地球天然交变电磁场的基本理论，研究了磁静日、磁暴时的视电阻率的变化特征。
