The quiet time characteristics of equatorial electrojet (EEJ), counter electrojet (CEJ), and solar quiet (Sq) day geomagnetic field over two decades (1980–2002) are established using Principal component analysis (PCA) from equatorial (Ettaiyapuram) and off‐equatorial (Hyderabad) Magnetic Observatories, India, over sunspot cycles 21–23. The patterns of normal field shows that the diurnal amplitudes were strong during equinox compared to other seasons. Varying contributions of abnormal field in different Lloyd's seasons were evident in different phases of sunspot cycle. The diurnal amplitudes have reduced from the 21st to the 23rd sunspot maxima following the trend of weakening of sunspot cycle. Analysis of seasonal means shows evening CEJs were more pronounced when compared to morning and afternoon in different phases of sunspot cycle. The abnormal field variations have a strong correlation with the occurrence of afternoon CEJs during solar minima; a correlation of seasonal occurrences of CEJs with phases of sunspot cycles is revealed.

中文翻译：

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太阳黑子周期在正常和异常地磁场上的印记：来自印度赤道和低纬度地区的案例研究

赤道电喷（EEJ），反电喷（CEJ）和太阳静（Sq）日地磁场在过去20年（1980-2002）中的静时特性是使用来自赤道（Ettaiyapuram）的主成分分析（PCA）建立的。印度赤道（海得拉巴）磁观测站，太阳黑子周期为21-23。正常场的模式表明，春分期间的昼夜振幅比其他季节要强。在太阳黑子周期的不同阶段，不同劳埃德季节的异常场贡献是明显的。随着黑子周期减弱的趋势，日峰值从第21个到第23个黑子最大值减小。对季节性平均值的分析表明，与黑子周期不同阶段的早晨和下午相比，晚上的CEJ更为明显。在太阳极小期间，异常场的变化与下午CEJ的发生有很强的相关性。揭示了CEJs的季节性发生与黑子周期周期的相关性。