卫星测高应用中的电离层延迟滤波处理的必要性

Necessity for filtering for ionospheric delay in the applications of satellite altimetry

针对卫星测高应用中电离层延迟的精细化处理问题,分析了电离层延迟滤波处理的必要性.利用Jason-3卫星1 s电离层延迟数据研究了电离层延迟的空间变化特性,分析了滤波前后电离层延迟变化的差异及其产生原因.通过Jason-3卫星前100个周期的电离层延迟双频改正数据计算的1 s差分序列的标准差约为1.49 cm,其与实际电离层变化情况的差异表明原始电离层延迟双频改正包含1 cm量级的误差,滤波处理后电离层延迟1 s差分序列的标准差约为0.05 cm,更合理地反映了电离层电子含量的空间变化情况.卫星测高应用特别是需要进行沿轨海面高差计算的应用中电离层延迟滤波处理非常必要,若不进行滤波处理,对于Ku频段测高应用,沿轨海面坡度的计算将包含约1.5 cm/5.8 km的误差.

To accurately compute the ionospheric delay in satellite altimetry application, the necessity of filtering for ionospheric delay is analyzed. The space change characteristics of ionospheric delay is studied using 1 s sampled Jason-3 satellite data, the difference of ionospheric delay before and after filtering and its reason is analyzed. The standard deviation of 1 s differential sequence computed through dual-freqency ionospheric delay correction data of the first 100 cycles of Jason-3 is 1.49 cm, the discrepancy comparing with the actual change of ionosphere shows that original dual-freqency ionospheric delay correction contains 1 cm level error. The standard deviation of ionospheric delay turns to be 0.05 cm after filtering, which matches the actual change of space ionospheric electron content more reasonably. In the satellite altimetry application especially which needs to calculate sea surface height change along satellite ground track, the process of ionospheric delay filtering is very necessary. If filtering were not done in the Ku band altimetry application, the result of sea slope along track would contain error of 1.5 cm per 5.8 km.