中文摘要：

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。

英文摘要：

Using ionosphere TEC data provided by IGS for the years 2000 to 2012,we studied ionosphere TEC asymmetry between the southern and northern hemispheres.By analyzing the Asymmetry Index（AI）of the TEC daily mean between the southern and northern hemispheres,we found that the absolute value of the maximum concentration of AI was about 0.4,the absolute value of the minimum concentration was about 0.3,demonstrating that there is a numerical asymmetry in the ionosphere TEC between the southern and northern hemispheres.With the Fourier analysis method,we found that there is an annual cycle and a 1/3annual cycle existing in Asymmetry Index;more than 50%when the northern hemisphere ionospheric TEC exceeds the southern hemisphere ionospheric TEC in a year.The mean value was 58%,suggesting a temporal asymmetry of the ionosphere TEC between the southern and northern hemispheres.We analyzed the annua difference of the mean TEC between the southern and northern hemispheres,finding that the annual mean TEC of the northern hemisphere is higher than that of the southern hemisphere,and the Asymmetry Index of the annual mean TEC between the southern and northern hemispheres during 2000-2012 was about 0.036.Taking the asymmetry in the atmospheric distribution and the movement rule and thermosphere into consideration,we discuss the reasons for the asymmetry of the ionosphere TEC between the southern and northern hemispheres.