Corrected event dataset of FengYun-4A Lightning Mapping Imager (FY-4A LMI), 2019–2023

The Lightning Mapping Imager (LMI) aboard FengYun-4A (FY-4A) has accumulated substantial observational data. To address remaining systematic geolocation deviations, we propose a correction method using World Wide Lightning Location Network (WWLLN) as a reference. The LMI field of view is divided into 400 subregions (20×20 grid). Within each subregion, sensitivity experiments match LMI events with ground-based lightning to quantify systematic deviations, followed by a weighted curve-fitting approach to derive subregional correction curves. The fitted curves are applied to the original Level-2 products to construct a refined correction dataset. Based on over nine million matched LMI-WWLLN pairs (2019–2023), after correction the proportion of events with deviation ≤ 15 km increases from 36.0 % to 51.7 %, and ≤20 km increases from 58.2 % to 74.8 %. The coordinate deviations converge substantially, indicating improved geolocation performance. Across most of the LMI field of view, the coarse-estimate average error is within approximately 15 km (about 1.5 pixels), with the actual accuracy being better, excluding those undetermined regions with sparse lightning (e.g., Xinjiang, Mongolia) where robust fitting is not feasible. Independent validation using the high-precision Beijing Broadband Lightning Network (BLNET) for a severe convective case on 4 August 2019 shows that for 70 % of the events, longitude deviations are within ±0.069° (mean 0.016°) and latitude deviations are within ±0.046° (mean −0.016°), with the comprehensive geolocation error within approximately one pixel, achieving accuracy levels comparable to those obtained using regional high-precision lightning network post-processing corrections. The corrected dataset is publicly available at https://doi.org/10.11888/Atmos.tpdc.303312 (Zhang et al., 2026b).