<p>The accuracy of ionospheric correction products is a key factor in determining the convergence time and positioning accuracy of Global navigation satellite system (GNSS) augmentation positioning techniques such as Network Real-Time Kinematic (Network RTK) and Precise Point Positioning-Real-Time Kinematic (PPP-RTK). Under conditions where the Continuously operating reference station (CORS) network is sparse or ionospheric activity is high, the accuracy of ionospheric corrections deteriorates. In such cases, the ionosphere-weighted model is more suitable compared to the ionosphere-float and ionosphere-fixed models. However, in the ionosphere-weighted model, the accuracy of the ionospheric correction products is generally calculated based on empirical models, which makes it difficult to accurately describe the complex variations of ionospheric correction residuals during periods of high ionospheric activity. These residuals cannot be fully absorbed by model parameters, thus degrading the positioning performance. To address this issue, this paper proposes a new method. Based on the verified spatial correlation of ionospheric correction errors, a rigorous derivation is conducted to obtain the formulation for real-time ionospheric correction precision at interpolation point using the residuals modelled from surrounding reference stations. Experimental results show that, compared to the ionospheric correction precision calculated by empirical models, the proposed method provides a more accurate characterization of the spatiotemporal distribution of ionospheric correction residuals, especially under active ionospheric conditions. The incorporation of real-time ionospheric correction precision in the proposed method improves the ambiguity fixing rate and positioning accuracy of CORS services. Notably, during periods of heightened ionospheric activity, such as periods of ionospheric disturbance and high solar activity, the new method demonstrated significant improvements over existing methods.</p>