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±3TECU，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。
When formation flying spacecrafts are used as platform to gain earth oriented observation, precise baselines between these spacecrafts are always essential. Gravity recovery and climate experiment （GRACE） mission is aimed at mapping the global gravity field and its variation. Accurate baseline of GRACE satellites is necessary for the gravity field modeling. The determination of kinematic and reduced dynamic relative orbits of twin satellites has been studied in this paper, and an accuracy of 2 mm for dynamic relative orbits and 5 mm for kinematic ones can be obtained, whereby most of the double difference onboard GPS ambiguities are resolved.
