## 4 Discussion and Conclusions  
The main goal of this study was to evaluate the performance of experiments with and without data assimilation for predicting the ATs near Pingtung Airport on 5 August 2018. In the experiments with data assimilation, the 3 DVAR system of the WRF model was assimilated with observation data from the Doppler lidar wind profiler in Pingtung Airport. During the major impact period of 0500-1100 UTC (1300-1900 LST) on 5 August 2018, ATs triggered by sea breeze circulation gradually formed in southern Taiwan and reached their mature stage at 0700 UTC, resulting in a single, quasi-stationary line of convection along the west coast. Short-duration intense rainfall of more than 30 mm during 12 h was observed in data collected from the AWSs of the Cengwen, Yuemei, and Yanpu stations. This reduced horizontal visibility to \(\leq\)5 km at the Pingtung meteorological station, which limited pilots to fly only under the instrument flight rules instead of visual flight rules. The change of flight rules exerted a great impact on aviation operations. Compared with the C1 experiments without data assimilation (NDA01, NDA02, NDA03 and NDA04), the C2 experiments (DA01, DA02, DA03 and DA04) and the C3 group experiments (CDA01, CDA02, CDA03) that used the 3 DVAR system with wind profiler data exhibited greatly improved simulation accuracy of the locations, intensity of ATs and wind fields produced by the local circulations of the sea breeze and the mountains in southern Taiwan in the horizontal and vertical directions. The model QPF was also greatly improved in the experiments with data assimilation. The TS of the C2 experiments exhibited consistently higher skills at the thresholds of 5, 10, 15 and 20 mm than did those of the C1 experiments. Similarly, the BS of the C2 experiments had mostly higher skills at the various thresholds. For all the C1 and C2 experiments, TS and BS tended to be higher at the thresholds of 5 and 10 mm than those of 15 and 20 mm. The analyses of PPMCC and SRCC also revealed the better model performance in the C2 and C3 group experiments with data assimilation. Among the group C2, the DA04 experiment performed best in the analysis of BS, TS, RMSE, PPMCC and SRCC and performed comparable to the DA02 experiment in the analysis of BS. Thus, the DA04 experiment had the overall better evaluation than other experiments of DA01, DA02 and DA03. However, the TS was higher in CDA02 and CDA03 in DA04, which implies that as the implementation time of data assimilation approaches the occurrence time of ATs, the forecast performance of short-duration intense rainfall is greatly improved. As in the study of Ref. [56], our findings suggest that assimilation of Doppler lidar wind profiles into a WRF-3 DVAR system creates conditions that favor the development of ATs and upscale growth. Although the results of this study are only supported by a single case, they provide valuable clues to improve the prediction of ATs by using the assimilation of lidar wind profiler data at Pingtung Airport. In the future, more case studies of the assimilation of lidar wind profiler data should be conducted to improve the accuracy and applicability of the results. **Author Contributions:** Conceptualization, W.-K.S. ; Formal analysis, W.-K.S. and S.-J.T. ; Funding acquisition, P.-H.T. and W.-K.S. ; Investigation, W.-K.S. and S.-J.T. ; Methodology, W.-K.S. ; Project administration, P.-H.T. ; Software, W.-K.S., S.-J.T., W.-J.C. and I.-H.C.; Data curation, S.-J.T., W.-J.C. and I.-H.C.; Supervision, P.-H.T. and W.-K.S. ; Visualization, P.-H.T., W.-K.S. and S.-J.T. ; Writing--original draft, P.-H.T. and S.-J.T. ; Writing-review and editing, all authors. All authors have read and agreed to the published version of the manuscript. **Funding:** This study was supported by the Ministry of Defense, Taiwan, under the project \"Research on establishment of real-time warning system of thunderstorm at airport using lightning detection and numerical weather forecasting model\". **Institutional Review Board Statement:** Not applicable.