Modeling impact of FORMOSAT‐7/COSMIC‐2 mission on ionospheric space weather monitoring

For the past decade, the paucity of ionospheric observations has made it almost impossible to reconstruct the three‐dimensional structures of global ionospheric electron density. The Formosa Satellite‐3/Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT‐3/COSMIC, F3/C) constellation has provided ionospheric electron density profiles with high vertical resolution through radio occultation measurements. Slated for deployment starting in 2016, the FORMOSAT‐7/COSMIC‐2 (F7/C2) constellation will further provide more than 4 times the number of the F3/C occultation soundings. An observing system simulation experiment is conducted to determine the impact of F7/C2 on ionospheric weather monitoring. The results first show that the F7/C2 observations can reconstruct 3‐D ionospheric structure with a data accumulation period of 1 h, which can advance studies of small spatial/temporal scale variation/signatures in the ionosphere. Comparing to assimilation results of F3/C, the assimilation system significantly reduces the error arising in the models and observations after assimilating synthetic observations of F7/C2. During this observing system simulation experiment period, the averaged root‐mean‐square error percentage for the results of F7/C2 is about 4.4%, lower than that of F3/C 7.3%. Furthermore, even with an assimilation window of less than 60 min, the F7/C2 RMS errors still yield reliable values compared to the F3/C results. This paper represents a major advance in ionospheric weather monitoring for the future mission.

在过去的十年中，电离层观测的匮乏使得重建全球电离层电子密度的三维结构几乎不可能。福尔摩沙卫星三号/气象、电离层和气候星座观测系统（FORMOSAT - 3/COSMIC，F3/C）星座通过无线电掩星测量提供了具有高垂直分辨率的电离层电子密度剖面。计划于2016年开始部署的福尔摩沙卫星七号/COSMIC - 2（F7/C2）星座将进一步提供比F3/C掩星探测数量多4倍以上的数据。进行了一次观测系统模拟实验以确定F7/C2对电离层天气监测的影响。结果首先表明，F7/C2观测能够在1小时的数据积累周期内重建三维电离层结构，这可以推进对电离层中小尺度时空变化/特征的研究。与F3/C的同化结果相比，同化系统在同化F7/C2的合成观测后显著降低了模型和观测中产生的误差。在这次观测系统模拟实验期间，F7/C2结果的平均均方根误差百分比约为4.4%，低于F3/C的7.3%。此外，即使同化窗口小于60分钟，与F3/C结果相比，F7/C2的均方根误差仍然能得出可靠的值。本文代表了未来任务在电离层天气监测方面的一项重大进展。