Occurrence characteristics of plasma bubble derived from global ground-based GPS receiver networks
Occurrence characteristics of plasma bubble derived from global ground-based GPS receiver networks
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DOI：
10.1029/2007ja012605
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发表时间：
2008-05-02
影响因子：
2.8
通讯作者：
Tsugawa, T.
中科院分区：
文献类型：
--
作者：
Nishioka, M.;Saito, A.;Tsugawa, T.
利用地面GPS接收网络研究了等离子体气泡的发生特征。由全球GPS网络得到的等离子体气泡的出现率比其他观测技术得到的结果具有更高的空间和时间分辨率，因为它对观测的覆盖范围很广。利用该数据集对等离子体气泡产生的物理特性进行了详细的研究。利用赤道附近的23个GPS接收器揭示了2000-2006年间的这一现象。各地区的月发病率特征不同。虽然发现日落时滞效应对月变化起重要作用，但发现了两个不能用日落时滞情景解释的不对称性：(1)两至日之间的不对称性和(2)两分点之间的不对称性。沿地磁线积分的F区电导率的季节变化可以部分解释冬至的不对称性。利用2000~2006年的半年出现率，研究了太阳活动高峰期到太阳活动低峰期的年际变化。不同地区对太阳活动的依赖程度不同。2004年在亚洲地区对纬度/海拔的发生率进行了调查。结果表明，对于赤道倾角高度小于700公里的台站，其发生频度较高且恒定。HODE大于700公里时开始下降，大于900公里时几乎为零。
Occurrence characteristic of plasma bubble was studied using ground-based GPS receiver networks. The occurrence rate of plasma bubble derived from the global GPS network has higher spatial and temporal resolution than that derived from the other observational techniques because of its wide coverage of the observation. The physical characteristics of plasma bubble occurrence were studied in detail with this novel data set. Twenty-three GPS receivers around the dip equator were used to reveal the occurrence from 2000 to 2006. Characteristics of the monthly occurrence rates were different among the regions. Although it was found that sunset time lag effect plays an important role for the monthly variation, two asymmetries which could not be explained with the sunset time lag scenario were found: ( 1) asymmetry between two solstices and ( 2) asymmetry between two equinoxes. The seasonal variation of the F-region conductivity integrated along the geomagnetic field line could partially explain the solstice asymmetry. Semiannual occurrence rates from 2000 to 2006 were used to study the year-to-year variation from the high solar activity period to the low solar activity period. The dependency of the occurrence on the solar activity was different among the regions. Occurrence rates against the latitude/altitude were investigated in the Asian region in 2004. It was found that the occurrence was high and constant for a station whose height on the dip equator ( HODE) was less than 700 km. They began to decrease when HODE was higher than 700 km and was almost zero where it was higher than 900 km.