基于COSMIC掩星观测数据的NmF2全球分布特征研究

Study of the global distribution features of NmF2 by using COSMIC occultation data

利用COSMIC掩星观测获得的电离层电子密度剖面数据,研究了2007-2011年的电离层F2层峰电子密度(NmF2)的全球分布特征。结果发现,赤道电离层异常因地方时和经度而变化,在LT11-LT14期间存在明显的沿经度变化的四峰结构。在北半球夏季夜间,北纬60°区域NmF2显著增强,即广义的威德尔海异常现象;在南半球夏季夜间,在威德尔海区域也出现了NmF2增强的现象。此外,与太阳活动低年相比,太阳活动增强期间的威德尔海异常区域的地理范围明显增大。

The global distribution features of the ionospheric F2 layer peak electron density （NmF2） during the period of 2007-2011 were studied by using the ionospheric electron density profile data derived from COSMIC occultation observations. The results show that the equatorial ionospheric anomaly （EIA） changed with local time （LT） and longitude, and the four peaks structure of EIA varied with longitude between LT11 and LT14. In the summer local night of the northern hemisphere, remarkable increase of NmF2 occurred in the 60°N latitude zones, which is re- ferred to as the generalized Weddell Sea anomaly （WSA）. The NmF2 enhancements also took place in the Weddell Sea areas in the sumner local night of the southern hemisphere. Moreover, the geographic ranges of the WSA re- gions increased significantly during the periods of enhancing solar activity compared with those during the low solar activity year.