利用球冠谐分析方法和GPS数据建立中国区域电离层TEC模型
Modeling Regional Ionosphere Using GPS Measurements over China by Spherical Cap Harmonic Analysis Methodology
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摘要: 利用GPS实测资料建立了中国区域电离层TEC球冠谐分析模型(spherical cap harmonic analysis,SCHA),评估了该模型的精度和有效性。结果表明,该模型有较高的拟合精度,其拟合残差约为±3 TECU,且精度在时间和空间上分布较均匀。根据IGS分析中心发布的IONEX全球电离层数据(GIM),内插得到了区域内相应时段的平均电离层电子含量,并利用它对CSHA模型的零阶项系数~C0,0所表示的区域平均电离层电子含量进行了检核。结果表明,二者具有较高的一致性和相关性,其谱特征相关系数为0.993。由于SCHA模型较GIM模型利用了更多本区域的GPS观测数据,因此其拟合精度更高,拟合结果与实测数据更一致。对SCHA模型参数的时间序列进行谱分析,结果表明,该模型的模型系数较好地描述了区域电离层TEC的周期性变化特征。Abstract: Based on spherical cap harmonic analysis(SCHA) methodology,the SCHA model to fit regional ionosphere total electronic content(TEC) over China is developed,and the accuracy and validity of this new TEC model by the GPS measurements from two Chinese domestic GPS observation networks in 2004 are evaluated.The results show that SCHA model is preferable since the overall modeling residual with respect to TEC measurements is relatively small,and the residual distribution is well-proportioned within temporal and spatial domain.Moreover,the time series of SCHA coefficients reflect the procecss of ionospheric activity explicitly,e.g.,the coefficient 0,0 depicts the mean regional ionosphere TEC,which is confirmed by the result deduced by GIM parameters of CODE,one of IGS analysis centers.That implies that SCHA mode can be used to predicate regional ionospheric TEC.Due to more GPS measurements over China involved in the modeling,SCHA model provides more precise TEC estimation in the region than IONEX data delivered by IGS analysis centers.
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