This study presents a long-term, high-resolution precipitation dataset over South Korea generated by merging nationwide composite radar reflectivity with dense rain gauge observations from the Korea Meteorological Administration (KMA). The dataset provides precipitation at 10-minute temporal resolution and 0.5 km spatial resolution on a regular grid of 2305 × 2881 pixels, covering the period from 2016 to 2024.</p> <p>Rain gauge observations, originally recorded at 1-minute intervals, are quality-controlled and aggregated to 10-minute accumulations prior to merging. Radar inputs are obtained from the nationwide composite reflectivity product provided by KMA. To ensure temporal consistency in the merged precipitation fields, a radar–gauge bias correction scheme is applied in which scaling factors are updated at 10-minute intervals during precipitation events and constrained relative to preceding time steps. This approach reduces spurious temporal variability while maintaining sensitivity to evolving precipitation systems.</p> <p>Residual differences between bias-corrected radar estimates and gauge observations are interpolated using a Residual Radial Basis Function (RRBF) method. The method models spatially structured residuals to preserve fine-scale radar-derived variability while incorporating gauge-based corrections. The entire merging procedure is computationally efficient, requiring approximately one minute per 10-minute analysis, which supports near-real-time implementation.</p> <p>The dataset is evaluated through comparison with conventional geostatistical interpolation methods, with particular emphasis on bias characteristics and spatial coherence. The resulting product provides temporally continuous and spatially consistent precipitation fields suitable for hydrological applications, extreme rainfall analysis, and urban flood forecasting. The dataset, together with detailed documentation of the generation and validation procedures, is publicly available for research and operational use.