An effective interpolation strategy for mitigating the day boundary discontinuities of precise GNSS orbit products

A precise Global Navigation Satellite System (GNSS) satellite orbit is an essential prerequisite for precise point positioning (PPP). Due to the daily orbit discontinuities (DODs) between adjacent daily orbit products provided by the International GNSS Service, the interpolation accuracy at the epochs near the day boundaries cannot be as high as expected and can significantly degrade the positioning accuracy. This is especially for the emerging Beidou and Galileo satellites with larger DODs. In this study, a new interpolation strategy was proposed to mitigate the DOD effect by estimating the zero- to second-order biases between the orbits of two adjacent days. The results show that the proposed interpolation strategy outperforms the traditional interpolation strategies. The 3D orbit interpolation error for the last 10 min on each day is reduced from almost a few centimeters or even meters to millimeters, an improvement of approximately 86–99% for all satellites. PPP validation also provides concrete evidence of this improvement, as the DOD-induced satellite phase residuals are reduced significantly. Thus, the new interpolation strategy mitigates the DOD effect and helps multi-GNSS users obtain the highest interpolation accuracy at the day boundaries, which can be comparable to that at the non-day boundaries.