Feasibility of the Data Fusion Between Space-Borne and Ground-Based TEC Products

The space-borne observations like satellite altimetry (SA), Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) and radio occultation (RO) techniques are average distributed around world without any limitation on the Earth surface landforms, hence could be used as complemented observations for the ground-based Global Navigation Satellite System (GNSS) ionosphere total electron content (TEC) retrieval. However, all the three space-borne observations are limited below the low earth orbit(LEO) satellite orbits which could not reflect the whole ionosphere TEC values. In this research, the DORIS relate slant total electron content(STEC) were leveled up/down to consist with global ionosphere maps (GIM) mean STEC, and for SA and RO TEC products, sample regions where the GIM TEC root mean square(RMS) below 2 TECU were selected as reference, and the scaling factors between the space-borne TEC products and GIM TEC were calculated with data in January, 2014. The retrieved TEC products were transferred to unified ionosphere datum as GIM TEC products, and comparison results were satisfied to validate the effectiveness of the space-borne ionosphere retrieval techniques. And also, the differences between the space-borne TEC and GIM TEC were summarized and compared with the ionospheric pierce point (IPP) number. The results show that the adjusted space-borne retrieved TEC products have good agreement with GIM TEC on IPP density distributed areas and less coincident on areas where IPP are sparely distributed. As the accuracy of the space-borne ionosphere retrieval technique basically has no spatial variance, it could be concluded that the adjusted TEC retrieved from the three space-borne techniques could effectively improve the GIM TEC products on ocean area where ground GNSS observation are not enough.