太阳活动低年低纬地区VTEC变化特性分析

Analysis of Variation Characteristic of VTEC in the Low Latitude Region During Low Solar Activity

利用福州台站(26.1°N,119.3°E,磁纬14.4°N)电离层闪烁与TEC监测仪2006—2010年的观测数据,对该地区垂直总电子含量(VTEC)进行时间变化特性分析.结果表明,春秋冬三季的VTEC平均最高值出现在06:00 UT,夏季出现在08:00 UT,所有季节的平均最低值均出现在21:00 UT;VTEC变化存在季节异常和弱冬季异常,春秋季节高,冬夏季节低,夏季VTEC比冬季低且最大值出现时间延迟;VTEC在2006—2009年呈现下降的变化趋势,2010年开始增强,年际变化与太阳活动及地磁活动变化趋势具有较好的对应关系;VTEC变化与太阳活动存在很好的相关性,相关系数达到0.5以上,地磁活动则显示了弱相关的特性;F_(10.7)与VTEC的相关性随着每天Kp指数总值∑K_p的增大而减小.

Observational data obtained （26.1°N, 119.3°E, geomagnetic latitude by an ionospheric scintillation and TEC monitor at Fuzhou 14.4°N） during 2006--2010 is used to analyze the charac- teristic of temporal variation of vertical TEC in this region. The results show that the maximum value occurs at 06：00 UT during spring, autumn and winter while at 08：00 UT during summer, and the averaged minimum occurs at 21：00UT for all seasons. A seasonal anomaly of VTEC is found with the high value occurring during spring and autumn seasons while low value during summer and winter seasons; there is a weak winter anomaly of VTEC. The value in summer are relatively lower than that in winter and the occurrence time of maximum is delayed. VTEC reveals a decreasing tendency from 2006 to 2009 and increases during 2010, which is corresponding with the yearly varia- tion of solar and geomagnetic activity. The correlation analysis exhibits that the variation of VTEC has a good relation with solar activities with a value of over 0.5, while it shows a weak relationship with the geomagnetic activity. Correlation between F10.7 and VTEC decreases with the raise of total value of geomagnetic index Kp （∑Kp）.