Change of Ionospheric Crest in China Sector Based on GPS-TEC
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摘要: 利用中国南部地区七个站点的2004年GPS观测数据,对赤道异常中国扇区电离层TEC的北驼峰位置和时间以及驼峰北侧电离层梯度进行了分析,结果表明:驼峰位置随季节改变,介于地理北纬17.5°～22.5°之间,冬季月份相对为低,分季月份相对为高,年平均位置约在北纬20°附近;驼峰出现时间也随季节在地方时13～16 h之间变化,冬季月份相对为早,夏季月份相对为晚,其出现时间的年平均值前者在地方时14 h前后,后者约在地方时15～16 h之间。驼峰区电离层TEC存在纬向梯度,其梯度也随地方时和季节而改变,夜侧梯度在地方时4.5 h前后为极小,且在不同季节其变化幅度不大,而日侧梯度在地方时13.5～16.5 h时段出现极大,且在不同季节差异较大,分季要高于冬季和夏季。Abstract: The variations of ionospheric TEC (total electron content) of equatorial anomaly are studied using the data from seven GPS sites of China region in 2004, including the occurrence latitude and time of the crest and the ionospheric gradient. Results show that the latitude of the crest varies from 17.5°N to 22.5°N in different seasons. It is higher in equinoxes and lower in winter, and the mean of occurrence latitude is about 20°N. The occurrence time of the crest varies also between 13 h and 16 h in local time (LT). It is earlier in winter and later in summer, and the mean time is about 14 h LT for the former and between 15 and 16h LT for the latter. It is found that there is the gradient of ionospheric TEC along the longitudinal chain, which vary with the local time and seasons. The minimum of gradient occur in nightside about 4.5 h LT and the maximum appears in dayside between 13 h and 16 h LT. Moreover, the variations of gradient is smaller in different seasons for the nightside and turn notable for the dayside, and the gradient is greater in equinoxes than summer and winter in dayside.
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Key words:
- GPS /
- total electron content /
- equatorial anomaly /
- gradient
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