Effect of phase centre variation on tropospheric delay in PPP-AR with low-cost global navigation satellite systems receiver and antenna

As low-cost global navigation satellite systems receiver and antenna become increasingly prevalent for water vapour monitoring, precise millimetre-level characterisation of instrument biases is crucial for maintaining measurement accuracy and reliability. This study examines the impact of phase centre variation (PCV) corrections on zenith wet delay (ZWD) accuracy in precise point positioning (PPP) solutions using low-cost systems. The results show that PCV corrections significantly improve ZWD estimation, reducing bias and RMS by 66% and 31% in ambiguity float PPP, and by 71% and 38% in ambiguity fixed PPP. In addition, integer ambiguity resolution offers no significant improvement in ZWD accuracy without PCV correction. When PCV corrections and ambiguity fixing are applied, low-cost receivers demonstrate ZWD estimates comparable to those of high-precision geodetic receivers, with a deviation of 0.2 mm and an RMS of 2 mm. However, variations in signal tracking and multipath suppression can still influence ambiguity fixing rates, resulting in slightly lower performance for low-cost receivers compared to their high-precision counterparts. The study concludes that deploying low-cost receivers with calibrated antennas offers a cost-effective approach to increasing the spatial resolution of atmospheric water vapour measurements, thereby enhancing weather monitoring and early warning systems, particularly for localised extreme weather events.