Currently, solar activity has entered the peak year of its 25th cycle, which is significantly and critically impacting the positioning accuracy and reliability of the Global Navigation Satellite System (GNSS). Intense ionospheric scintilla- tion and fluctuations in Total Electron Content (TEC) can lead to substantial errors in GNSS observations, particularly in low-latitude regions. To address this issue, this study proposed an improved Network Real-Time Kinematic (NRTK) positioning method tailored for complex ionospheric environments. By leveraging the warning information of iono- spheric disturbances from the server-end, the proposed method enhances both the accuracy and availability of NRTK positioning with ionospheric residual estimation and adaptive stochastic model at the user-end. Using the data at Hong Kong regional Continuously Operating Reference Station (CORS) from September 2024, we demonstrated that during the high solar activity year, the ionospheric disturbances index Rate Of TEC Index (ROTI) exhibited a strong positive correlation (correlation coefficient: 0.91) with ionospheric interpolation errors on the server-end and a nega- tive correlation (correlation coefficient: − 0.9) with fixing rate on the user-end. Compared to the conventional NRTK method, our approach significantly improves the rover positioning performance. The average fixing rate is increased from 58 to 84%, while the positioning accuracy is improved by 37.6% and 41.6% for the horizontal and vertical com- ponents, respectively. |
