Objectives With the continuous expansion of China's polar scientific expeditions, the demand for reliable and high-precision global navigation satellite system (GNSS) positioning services in Antarctica has become increasingly prominent. However, the Antarctic inland region is characterized by extremely harsh environmental conditions, sparse infrastructure, and limited communication capability, making it difficult to establish dense continuous GNSS observation networks or ground-based augmentation systems. Under these conditions, precise point positioning (PPP), which enables high-precision positioning using a single receiver with precise satellite orbit and clock products, provides an important technical solution for Antarctic inland applications.
Methods Based on GNSS observations from Antarctic international GNSS service (IGS) stations, including CAS1 and DAV1, as well as rare GNSS data collected at China's Kunlun station (KUNL) and Taishan station (TAIS) during the 41st Chinese national antarctic research expedition, this study systematically evaluates the positioning performance of BeiDou navigation satellite system(BDS)/GNSS in the Antarctic high-latitude region, with particular focus on China's inland Antarctic stations. Geomagnetically quiet days from March 1 to March 10, 2024, and the strong geomagnetic storm event on March 24, 2024, were selected for comparative analysis. Standard point positioning (SPP), undifferenced and uncombined PPP float solutions, and PPP ambiguity resolution (PPP-AR) solutions were assessed under both static and simulated kinematic modes for single-system GPS, BDS, Galileo, and multi-system combinations of GPS/BDS and GPS/BDS/Galileo. Positioning accuracy, initialization time, ambiguity fix rate, visible satellite number, geometric dilution of precision (GDOP), and the rate of total electron content index (ROTI) were comprehensively analyzed.
Results The results indicate that multi-GNSS observations significantly enhance satellite availability in Antarctica, with approximately 50-60 visible satellites observed at Antarctic stations. The positioning accuracy of single-frequency SPP is approximately 2.7-3.3 m, while dual-frequency SPP improves the accuracy to about 2.0 m, highlighting the advantage of dual-frequency observations in polar environments. Compared with SPP, static PPP ambiguity resolution (PPP-AR) solutions achieve decimeter- to centimeter-level accuracy, demonstrating the feasibility of PPP for high-precision Antarctic positioning. BDS and Galileo outperform GPS in both positioning accuracy and ambiguity fixing capability. Multi-GNSS integration, especially the GPS/BDS/Galileo combination, further improves positioning stability and shortens initialization time, with the initialization time of the CAS1 and DAV1 reduced to about 12 min under favorable conditions. The average PPP-AR initialization times of high-latitude stations such as TAIS and KUNL are generally longer than those of the relatively lower-latitude CAS1 and DAV1 stations. This may be mainly attributed to the combined effects of satellite geometry, and observation noise in ice-snow environments in the high-latitude inland Antarctic region. Compared with static PPP, the overall performance in terms of average initialization time and average three-dimensional positioning error of simulated kinematic PPP-AR is degraded. For the four Antarctic stations, both kinematic and static PPP float resolution achieve centimeter-level average 3D positioning accuracy. The average convergence times of static and kinematic PPP float solutions at CAS1 and DAV1 are less than 15 minutes, whereas TAIS and KUNL exhibit longer average convergence time. During the geomagnetic storm, PPP positioning errors increased and ROTI values fluctuated markedly at Antarctic stations, suggesting that enhanced polar ionospheric disturbances adversely affect PPP performance.
Conclusions Overall, this study demonstrates that BDS/GNSS PPP, particularly multi-GNSS PPP, is an effective and reliable approach for high-precision positioning in Antarctic inland scientific expeditions. Meanwhile, the influence of space weather should be carefully considered in practical GNSS applications in polar regions.
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