Impact of Assimilating the FORMOSAT‐3/COSMIC and FORMOSAT‐7/COSMIC‐2 RO Data on the Midlatitude and Low‐Latitude Ionospheric Specification
Impact of Assimilating the FORMOSAT‐3/COSMIC and FORMOSAT‐7/COSMIC‐2 RO Data on the Midlatitude and Low‐Latitude Ionospheric Specification
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DOI：
10.1029/2018ea000447
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发表时间：
2018-12
影响因子：
3.1
通讯作者：
C. Hsu;T. Matsuo;Jann‐Yenq Liu
中科院分区：
文献类型：
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作者：
C. Hsu;T. Matsuo;Jann‐Yenq Liu
全球导航卫星系统（GNSS）无线电掩星（RO）任务，例如福尔摩沙卫星三号/气象、电离层和气候星座观测系统（FORMOSAT - 3/COSMIC）以及即将发射的福尔摩沙卫星七号/COSMIC - 2，为监测空间天气提供了电离层的有价值的剖面信息。这项研究表明，借助数据同化，FORMOSAT - 3/COSMIC和FORMOSAT - 7/COSMIC - 2任务监测高度变化的电离层天气的能力可以得到显著提升。格点统计插值（GSI）电离层是一种专门为低纬度和中纬度电离层设计的新型数据同化系统。首先利用2013年1月的实际FORMOSAT - 3/COSMIC无线电掩星总电子含量（TEC）数据展示了GSI电离层的能力。在一个耦合的等离子体层 - 电离层 - 热层模型中，电离层赤道电离异常的特征与利用独立的地基GPS数据生成的TEC图更加一致。与没有数据同化的对照模拟情况相比，通过同化FORMOSAT - 3/COSMIC无线电掩星数据，一致性提高了约50%。为了评估未来无线电掩星任务对电离层天气状况的影响，利用合成的无线电掩星TEC数据进行了对比观测系统模拟实验（OSSEs）。FORMOSAT - 7/COSMIC - 2的一次OSSE表明，GSI电离层在地磁纬度±30°范围内能够使电离层状况比对照情况改善67%，这与2009年FORMOSAT - 3/COSMIC所带来的改善（61%）相当。这些结果表明，借助FORMOSAT - 7/COSMIC - 2无线电掩星TEC数据，在改善对实际电离层天气的监测方面具有巨大潜力。
Global Navigation Satellite System (GNSS) Radio Occultation (RO) missions, such as the Formosa Satellite‐3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT‐3/COSMIC) and the upcoming FORMOSAT‐7/COSMIC‐2, provide valuable profiling of the ionized atmosphere for the monitoring of space weather. This study shows that the FORMOSAT‐3/COSMIC and FORMOSAT‐7/COSMIC‐2 missions' ability to monitor highly variable ionospheric weather can be considerably extended with the help of data assimilation. The Gridpoint Statistical Interpolation (GSI) Ionosphere is a new data assimilation system designed specifically for the low‐latitude and midlatitude ionosphere. The capability of the GSI Ionosphere is first demonstrated with actual FORMOSAT‐3/COSMIC RO total electron content (TEC) data for January 2013. Features of the ionospheric equatorial ionization anomaly in a coupled plasmasphere ionosphere thermosphere model become more consistent with the TEC maps created with independent ground‐based GPS data. The consistency has improved by assimilation of FORMOSAT‐3/COSMIC RO data up to about 50% in comparison to the control simulation case without data assimilation. To evaluate the impact of future RO missions on ionospheric weather specification, comparative Observing System Simulation Experiments (OSSEs) are carried out with synthetic RO TEC data. An OSSE of FORMOSAT‐7/COSMIC‐2 shows that the GSI Ionosphere can improve the ionospheric specification within ±30° geomagnetic latitude by 67% over the control case, which is comparable to the improvement yielded by FORMOSAT‐3/COSMIC for 2009 (61%). These results indicate a great potential for improving the monitoring of realistic ionospheric weather with the help of FORMOSAT‐7/COSMIC‐2 RO TEC data.