Evaluation of regional ionospheric grid model over China from dense GPS observations

The current global or regional ionospheric models have been established for monitoring the ionospheric variations. However, the spatial and temporal resolutions are not enough to describe total electron content (TEC) variations in small scales for China. In this paper, a regional ionospheric grid model (RIGM) with high spatial-temporal resolution (0.5° × 0.5° and 10-min interval) in China and surrounding areas is established based on spherical harmonics expansion from dense GPS measurements provided by Crustal Movement Observation Network of China (CMONOC) and the International GNSS Service (IGS). The correlation coefficient between the estimated TEC from GPS and the ionosonde measurements is 0.97, and the root mean square (RMS) with respect to Center for Orbit Determination in Europe (CODE) Global Ionosphere Maps (GIMs) is 4.87 TECU. In addition, the impact of different spherical harmonics orders and degrees on TEC estimations are evaluated and the degree/order 6 is better. Moreover, effective ionospheric shell heights from 300 km to 700 km are further assessed and the result indicates that 550 km is the most suitable for regional ionospheric modeling in China at solar maximum. © 2016 Institute of Seismology, China Earthquake AdministrationScience and Technology Commission of Shanghai Municipality: 12DZ2273300 Chinese Academy of Sciences National Natural Science Foundation of China: 11573052 National Natural Science Foundation of ChinaThis work was supported by the National Natural Science Foundation of China (NSFC) Project ( 11573052 ), Shanghai Science and Technology Commission Project ( 12DZ2273300 ) and Key Laboratory of Planetary Sciences, Chinese Academy of Sciences . Great appreciation is extended to data sources for providing the free access. Xin Zhao , is a Master student of Shanghai University and Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai, China. His main topics are focused on Satellite Navigation, Space Geodesy and GNSS Ionospheric Sounding