基于极大验后推估理论的全球电离层地图预报

Prediction of Global Ionospheric Map Using the Theory of Maximum Posterior Estimation

提出了一种基于极大验后估计理论的全球电离层预报方法,基于中国科学院电离层分析中心(CAS)提供的快速全球电离层地图(GIM),实现了1天、2天和5天GIM的预报。以国际GNSS服务组织(IGS)最终GIM、Jason测高卫星提供的电离层观测信息及全球GNSS基准站实测电离层总电子含量(TEC)为基准,评估了2008-2017年CAS电离层预报GIM在全球大陆及海洋区域的精度,并与欧洲定轨中心(CODE)、欧洲空间局(ESA)和西班牙加泰罗尼亚理工大学(UPC)的预报GIM进行对比。在评估时段内,与IGS-GIM相比,CAS预报GIM精度为2.4~3.1 TECU;与测高卫星TEC相比,CAS预报GIM的精度为5.1~6.6 TECU;与全球基准站实测TEC相比,CAS预报GIM的电离层延迟修正精度优于80%。总体来看,CAS预报GIM与CODE预报GIM精度相当,显著优于ESA和UPC预报GIM。

A method based on maximum posterior estimation is proposed for the prediction of global ionosphere.Using the rapid ionospheric products from the Chinese Academy of Sciences(CAS),the 1-,2-and 5-day predicted Global Ionospheric Maps(GIM)are routinely generated with the proposed algorithm.The qualities of CAS predicted GIMs as well as those from the Center for Orbit Determination of Europe(CODE),European Space Agency(ESA)and the Polytechnic University of Catalonia(UPC),are evaluated during 2008-2017 using Total Electron Content(TEC)references derived from the final GIMs of the International GNSS Service(IGS),Jason altimetry and global GNSS reference stations.The consistency between CAS predicted GIMs and IGS final GIMs is 2.4~3.1 TECU during the test period.Compared to Jason derived TEC observables,the precision of CAS predicted GIMs is on the level of 5.1~6.6 TECU over global oceanic regions.Compared to the TECs derived by global reference stations,the ionospheric delay correction accuracy of CAS predicted GIMs is better than 80%.Overall,the quality of CAS predicted GIM performs at the same level with that from CODE,which is significantly better than ESA and UPC predicted ones.