Accuracy assessment of global ionospheric maps based on occultation data
global ionospheric map (GIM) data are widely used in research on the ionosphere,and its accuracy assessment is of great significance for studying the nature of the ionosphere and improving positioning accuracy. In order to assess the accuracy of the GIM,this paper calculated the constellation observing system for meteorology,ionosphere and climate (COSMIC) and vertical total electron content (VTEC) in 2008 and 2012 based on the ionPrf product provided by the University Corporation for Atmospheric Research (UCAR). The accuracy of GIM from the International Global Navigation Satellite System Service (IGS) was evaluated by histogram statistics,latitude distribution statistics,annual cumulative day distribution statistics,and local time distribution statistics. The results show that:① The mean of bias is 5.09 TECU in 2008 and 9.90 TECU in 2012;② The bias of each latitude in 2008 ranges from 3 to 8 TECU,and that in 2012 ranges from 6 to 16 TECU;③ The mean of bias achieves its maximum value in January and its minimum value between the summer solstice and the fall equinox;④ The bias of each local time in 2008 ranges from 3 to 7 TECU,and that in 2012 ranges from 6 to 14 TECU;⑤ In years with high solar activity,the bias reflects equatorial anomalies,semi-annual anomalies,and winter anomalies. In summary,the accuracy of the GIM is closely related to solar activity,geographic location,seasonal variations,and daily variations.
ionospheretotal electron content (TEC)radio occultationglobal ionosphere map (GIM)accuracy assessment
万方数据
维普
