Abstract: Time delay in the ionosphere is the most important source of error in the Global Navigation Satellite System. In particular, the ionosphere in polar regions is changeable, resulting in reduced precision of global positioning systems (GPS). Therefore, an appropriate broadcast ionospheric model is needed for the polar regions. Vertical total electron content data were derived from the GIM model, and the effects of two correction models (two versions of the Klobuchar model adopted by GPS and the BeiDou Navigation Satellite System [BDS], and the NeQuick model) on the ionospheric delay of positioning accuracy were compared. At latitudes higher than 57.5°N or S, the Klobuchar model adopted by GPS had a negative effect in most cases, but performed better than that adopted by the BDS. The NeQuick model performed worse at high latitudes than at middle and low latitudes, with a correction effect of about 40%.

Key words: Klobuchar model, NeQuick model, GIM model, TEC, polar