电离层峰值变化特性及其影响因素分析

电离层延迟误差是影响GNSS高精度定位的重要误差来源之一,分析和掌握各因素对电离层变化规律的影响,有助于建立高精度电离层模型。为此,本文采用IGS中心提供的1999年~2015年电离层GIM数据计算南北半球不同经度圈的峰值不对称指数,分析其与太阳活动情况和地磁活动情况的相关性,并对单日电离层峰值变化情况进行分析。通过分析表明：(1)峰值不对称指数具有明显的年周期性和季节周期性；(2)西半球峰值不对称指数与太阳黑子数的相关性大于东半球,但东半球和西半球峰值不对称指数与地磁指数相关性几乎相同；(3)除08:00 LT ~ 10:00 LT(Local Time) 赤道两侧不存在明显峰值外,剩余时段均有明显的峰值,且通常在12:00 LT ~ 16:00 LT 取得极大值。

Characteristics Analyses of Ionospheric Delay Peak Value and its Impact Factors

Ionospheric delay error is one of the main error sources in Global Navigation Satellite System (GNSS) positioning. It is contribute to build a higher ionospheric model via analyzing and grasping every factor which influence the changing rules of the ionosphere. In this reason, this paper uses the Global Ionosphere Maps (GIM) data provided by the International Global Navigation Satellite System Service (IGS) center from 1999 to 2015 to calculate the asymmetry index of Total electron content (TEC) peak values in the northern and southern hemisphere. Then, analyzing the correlation between the asymmetry index of TEC peak values and the sunspot number as well as geomagnetic activity index. At last, the variation of the peak values in different longitudes during a day are analyzed. After analyzing the data, it can be concluded that: (1) the asymmetry index of TEC peak values have seasonal cycle and annual cycle obviously, either in the western hemisphere or in the eastern hemisphere; (2) the asymmetry index of TEC peak values are much more related with sunspot in western hemisphere than that of in eastern hemisphere; while the asymmetry index of TEC peak values has a parallel relation with geomagnetic activity index in both eastern hemisphere and western hemisphere; and (3) other than unobvious peak value at 08:00 LT to 10:00 LT on both side of the equator, the rest hours have obvious peak values in every period, especially peaking at 12:00 LT ~ 16:00 LT.