Abstract A local maximum value of ionospheric total electron content (TEC) in midlatitude regions, named midlatitude ionospheric peak in this study, has been frequently observed during both the daytime and nighttime. We have carried out a modeling study of midlatitude ionospheric peaks in TEC using the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM) to investigate possible mechanisms driving these peaks. Comparisons between model results and Global Position System (GPS) TEC observations in the solar minimum year of 2009 show that TIEGCM can reproduce the nighttime and daytime midlatitude ionospheric peaks. Model results indicate that midlatitude ionospheric peaks in the daytime and nighttime are likely caused by different mechanisms. Nighttime midlatitude ionospheric peaks are attributed to the downwards-moving plasma ambipolar diffusive flux from the plasmasphere. However, the daytime upwards-moving plasma ambipolar diffusive flux and poleward meridional winds, which can cause ionospheric depletion, might play dominated roles in producing midlatitude ionospheric peaks in the early morning in the winter season.

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使用 TIEGCM 研究 TEC 中纬度电离层峰值

摘要 中纬度地区电离层总电子含量（TEC）的一个局部最大值，在本研究中称为中纬度电离层峰值，在白天和夜间经常出现。我们使用热层电离层电动环流模型 (TIEGCM) 对 TEC 中纬度电离层峰值进行了建模研究，以研究驱动这些峰值的可能机制。模型结果与 2009 年太阳活动极小年全球定位系统 (GPS) TEC 观测结果的比较表明，TIEGCM 可以再现夜间和白天的中纬度电离层峰值。模型结果表明，白天和夜间的中纬度电离层峰值很可能是由不同的机制引起的。夜间中纬度电离层峰值归因于来自等离子体层的向下移动的等离子体双极扩散通量。然而，白天向上移动的等离子体双极扩散通量和极地经向风会导致电离层损耗，可能在冬季清晨产生中纬度电离层峰值中起主导作用。