Accuracy Analysis of GNSS Global Broadcast Ionospheric Model

Global navigation satellite system (GNSS) broadcast ionospheric model is the main method for single frequency users to correct ionospheric delay. GPS, Galileo and BDS-2 satellites all broadcast ionospheric parameters. The BDS-3 test satellites broadcast the BDGIM's (BeiDou global ionospheric delay correction model) parameters, using to correct the global ionospheric delay. Using the International GNSS Service (IGS) GIM (global ionosphere maps) products and the GPS dual-frequency observations from more than 140 GNSS observation stations around the world, the correction accuracies of global broadcast ionosphere model of GPS, Galileo and BDS-3 are analyzed in the global range, different latitudes and different regions. The models are compared with the ionosphere model of IGS prediction (IGS P1 and IGS P2) as well. The results show that the correction accuracy of IGS P1 and IGS P2 products is generally optimal, and BDGIM's parameters are better than Gal NeQuick and GPS K8. For the newly released BDGIM's parameters of BDS-3, the correction accuracy (i.e. root mean square, RMS) is about 3.58 TECU in the global scope, and the correction rate is about 77.2%, with the same correction accuracy in different regions of the world.