In this work, the Global Ionospheric Maps (GIMs) are used to analyze the behavior of the mid-latitude ionospheric trough (MIT) during the solar cycle 24 (2008–2019). This analysis is performed for the Northern and Southern Hemispheres at different local times: 00, 02 and 04 LT. We study the MIT position dependence on the phase of the solar cycle, seasonal, and geomagnetic activity during the post-midnight period. We find that the MIT position shows an interhemispheric asymmetry. Its equatorward movement from low to high solar activity is about $3°$ and $1°$ for Northern and Southern Hemisphere respectively for the three local times analyzed. There is also a clear seasonal variation, the shift between winter and summer is around $3°$ and $1°$ at 00 LT and $6°$ and $4°$ at 04 LT for the Northern and Southern Hemispheres, respectively. In general, the MIT position reaches the highest geomagnetic latitude in winter, without variation with local time. However, in summer it takes the lowest geomagnetic latitude, moving towards the equator from 00LT to 04LT. The MIT position moves equatorward under disturbed geomagnetic conditions, and the difference between the MIT position during quiet and perturbed days is greater in the Northern than in the Southern Hemisphere. In addition, the periodicity of the variability of the MIT position for both Hemispheres versus the solar wind speed and IMF Bz-component are analyzed using the wavelet transform, showing a clear dependence between them during the descending and minimum solar phase at 13.5 and 27-day time scales.

在这项工作中，全球电离层图 (GIM) 用于分析中纬度电离层槽 (MIT) 在太阳活动周期 24 (2008-2019) 期间的行为。该分析针对北半球和南半球在不同的本地时间执行：00、02 和 04 LT。我们研究了 MIT 位置对后午夜时期太阳周期阶段、季节性和地磁活动的依赖性。我们发现 MIT 位置显示出半球间的不对称性。它从低太阳活动到高​​太阳活动的赤道运动大约是$3°$ 和 $1°$分别为北半球和南半球的三个本地时间进行分析。也有明显的季节变化，冬夏交替$3°$ 和 $1°$ 在 00 LT 和 $6°$ 和 $4°$分别为北半球和南半球的 04 LT。一般来说，MIT位置在冬季达到最高地磁纬度，与当地时间没有变化。然而，在夏季，它需要最低地磁纬度，从 00LT 到 04LT 向赤道移动。麻省理工学院的位置在受扰动的地磁条件下向赤道移动，北半球安静和扰动期间麻省理工学院位置之间的差异比南半球更大。此外，使用小波变换分析了两个半球的 MIT 位置随太阳风速和 IMF Bz 分量变化的周期性，在 13.5 和 27 度的下降和最小太阳相位期间，它们之间显示出明显的相关性。白天的时间尺度。