掩星大气反演中的电离层二阶项效应的分析

以MSIS90大气模型、3D NeUoG电离层模型和IGRF11地磁场模型为基础,用三维射线追踪法模拟了无线电掩星中电离层二阶项残差的变化,研究了其在不同太阳活动强度、不同地方时、不同方位角下的变化,以及在全球的分布特征。结果表明,二阶项残余误差通常在亚cm级水平,但在较高太阳活动水平下,或当掩星发生地位于中低纬度地区,掩星方位角约为0°或180°时,二阶项残余误差可达到cm级,而且在全球分布呈现出“三峰”结构。

Analysis of Second Order Ionospheric Effects on Atmospheric Parameters Estimation in Radio Occultation

In the study of atmospheric inversion based on radio occultation, the residual ionospheric errors have great influence on the accuracy and the second order errors are not ignorable. In this paper, MSIS90 atmospheric model, 3D NeUoG ionospheric model and IGRF11 geomagnetic model are all collected, and 3D ray tracing method was used to simulate the changes of the second order residual ionospheric errors in radio occultation. Under different solar activities, local time, azimuth, the second order errors were analyzed, especially for its global distribution. The results show that second order errors are usually in sub-centimeter level, but up to centimeter level under higher solar activity or in middle and low latitudes at 0° or 180° azimuth, and illustrate the structure of “three-peak” in globe. Therefore, in the occultation data process, the ionospheric monitoring must be strengthened and second order ionospheric errors must be eliminated effectively.