PPP-RTK atmospheric correction generation and service applicability : a case study during typhoon Saola and moderate geomagnetic disturbances in Hong Kong

Abstract

Complex space weather, such as typhoons and solar activity, can cause heavy rainfall and ionospheric disturbances, affecting the quality of Global Navigation Satellite System (GNSS) signals. Among GNSS positioning techniques, Precise Point Positioning Real-time Kinematic (PPP-RTK) uses atmospheric corrections and bias products to achieve fast convergence and high accuracy solutions, with the quality of ionospheric and tropospheric corrections being critical to PPP-RTK performance. While most research focuses on improving user positioning accuracy, few studies address PPP-RTK applicability under complex space weather. This study uses GNSS data from Hong Kong to generate and verify PPP-RTK corrections during Typhoon Saola and a moderate geomagnetic disturbance in solar cycle 25. Results show that derived tropospheric zenith wet delay (ZWD) aligns with historical rainfall data, and ZWD model residuals are positively correlated with the typhoon process, with standard deviations below 4 mm. The ionospheric interpolation errors increase before and after landfall, and the possible reason is that the ionospheric perturbations in the eye of the storm are fewer than those at the edges of the typhoon. Across days, ionospheric interpolation error standard deviations range from 5 to 10 cm. PPP-RTK validation using these corrections achieves 1–2 cm accuracy with near-instantaneous convergence in east and north directions, while 2–5 min are needed for the up direction to converge to 2–6 cm accuracy. The assessment and validation confirm the high precision of atmospheric corrections and the applicability of PPP-RTK during typhoon Saola and moderate geomagnetic disturbances in a dense network in Hong Kong.