Zhang, Keke, Li, Xingxing, Wu, Jiaqi, Yuan, Yongqiang, Li, Xin, Zhang, Xiaohong, and Zhang, Wei
Precise knowledge of orbit represents a fundamental requirement for the earth observing satellite missions to achieve their advanced objectives. The integer ambiguity resolution (IAR) has proved to be a key to utmost accuracy in space navigation. Generally, there are two typical IAR methods widely used in the orbit determination of low Earth orbit (LEO) satellites, the classical double‐difference (DD) IAR and new single‐difference (SD) IAR. Based on one‐year observations of Gravity Recovery and Climate Experiment Follow‐On (GRACE‐FO) and Sentinel‐3 missions, this study is dedicated to a comprehensive analysis of the differences of the products used, implementation details and ambiguity fixing performance for different IAR methods in LEO precise orbit determination (POD), and discusses how these differences influence the orbit solutions. The results show that the orbit accuracy improvement contributed by the ambiguity fixing varies with the adopted IAR methods. SD IAR can contribute to a representative reduction of 1–4 mm in satellite laser ranging (SLR) residuals compared to the float solutions. The application of bias products from different analysis centers leads to marginal differences for the ambiguity fixing. For DD IAR method, the different ways to form the double‐difference ambiguity yield different performances in POD. The DD IAR of space‐ground baselines can achieve a comparable performance to SD IAR, while the benefit of ambiguity fixing is largely weakened when forming space‐space baseline. Furthermore, we also analyze the contribution of the ambiguity fixing to the accuracy and robustness of the kinematic orbit and discuss its great potential for the future applications. Plain Language Summary: Obtaining accurate orbit information of low Earth orbit satellite is an essential prerequisite for the geodetic and remote sensing missions to support their operation. Today, the onboard Global Navigation Satellite System (GNSS) technology has been commonly recognized as the optimal way to produce high‐quality orbit for these Earth‐observation satellites. However, due to the existence of hardware delays in both signal transmitter and receiver, the inherent accuracy of carrier phase signal is not fully exploited. Removing the effects of these errors plays a key to achieve the ultimate accuracy of GNSS‐based orbit. Nevertheless, different methods of separating these hardware delays from GNSS observations eventually lead to accuracy discrepancy in satellite orbit recovery. Our study focuses on the several commonly used methods of eliminating the hardware delays in the precise orbit determination. We present a detailed analysis about the differences between these methods lying in the implementation details and performance, and discuss how these differences impact the orbit solutions. Using a wider set of Earth‐observation missions and data over a longer time span than before, we aim to answer the question which method is optimal or most appropriate for the recovery of satellite orbit and make suggestion for the future mission. Key Points: The differences in the implementation, fixing performance and accuracy between several ambiguity fixing methods in low Earth orbit (LEO) precise orbit determination (POD) are discussedThe single‐receiver integer ambiguity resolution represents the currently optimal choice for LEO PODWith the integer ambiguity fixing method, the kinematic orbit exhibits a great potential for the future applications [ABSTRACT FROM AUTHOR]