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利用2000~2012年的IGS电离层TEC数据,研究了南北半球电离层TEC的非对称性。首先对南北半球TEC日平均值的不对称指数(AI)进行了研究,结果表明,AI的极大值的绝对值集中在0.4左右,极小值的绝对值集中在0.3左右,表明南北半球电离层TEC存在数值上的非对称性;通过傅里叶变换,发现AI存在1a和1/3a周期;每年北半球电离层TEC高于南半球电离层TEC的时间比例均大于50%,平均值为58%,表明了南北半球电离层TEC存在时间上的非对称性。然后进一步分析了南北半球TEC年平均值的差异,发现了北半球TEC年平均值高于南半球的规律,2000~2012年的南北半球TEC年平均值的不对称指数在0.036左右。最后从全球大气分布及运动规律的南北非对称性和热层年度变化赤道非对称性两个角度,对南北半球电离层TEC的非对称性产生的原因做了初步分析。
Using the IGS ionospheric TEC data from 2000 to 2012, the asymmetry of ionospheric TEC in the northern and southern hemispheres was studied. Firstly, the asymmetry index (AI) of daily averages of TEC in the northern and southern hemispheres was studied. The results show that the absolute value of the maximum value of AI is about 0.4 and the absolute value of minimum value is about 0.3, indicating that the northern and southern hemispheres ionization Layer TEC exists asymmetric value. Through Fourier transform, it is found that AI exists for 1a and 1 / 3a periods. The annual percentage of ionospheric TEC in the northern hemisphere is higher than that in the southern hemisphere by more than 50% with an average of 58% , Indicating that there is a time asymmetry of ionospheric TEC in the northern and southern hemisphere. Then the differences of annual average TEC values in the northern and southern hemispheres were further analyzed. The average annual TEC values in the northern hemisphere were found to be higher than those in the southern hemisphere. The asymmetry index of annual TEC values in the southern and northern hemispheres from 2000 to 2012 was about 0.036. Finally, the causes of the asymmetry of the ionospheric TEC in the northern and southern hemisphere are analyzed from the perspective of the global asymmetry of the distribution and movement of the atmosphere and the equatorial asymmetry of the annual variation of the thermal layer.