Analysis on Multi-Factor Synergistic Hazards Mechanism of Wet Micro-Downburst: a Multi-Source Data Fusion Analysis Based on Passenger Vessel Capsizing Accident in Qianxi, Guizhou on 4 May 2025

Abstract. The research on the multi-factor synergistic disaster-causing mechanism of wet microbursts, constrained by the scarcity of monitoring data, constitutes a crucial bottleneck restricting the early warning and prevention of major accidents such as water vessel capsizing. Focusing on the catastrophic “5.4” passenger ship capsizing accident that occurred at 08:32 UTC (UTC is used throughout the paper) on 4 May 2025 at Dongfeng Reservoir in Qianxi, Guizhou Province, this study integrates multi-source data encompassing weather radar observations, surface meteorological observations, lightning monitoring, on-site surveillance videos, and disaster trace investigations. It overcomes the limitations of single-source or low-resolution monitoring data in previous cases such as the “Eastern Star” incident, and conducts a systematic analysis by integrating minute-level high-resolution observations, which cover dynamic characteristics, surface thermal responses, as well as video and disaster trace verification. The study reveals that the rapid descent of the strong radar echo core within the convective system triggers an explosive near-surface divergent wind field (with an instantaneous wind speed of 34.7 m s−1), accompanied by an abrupt drop of 14.9 °C in surface temperature and a sudden surge of 5.4 hPa in atmospheric pressure. The phase transition of ice-phase particles indicated by the radar differential reflectivity (ZDR) column, enhanced the downward motion through a feedback mechanism, and a hailfall occurred subsequent to the wind direction reversal. Meanwhile, the high-density zone of lightning activity coincided with the convective path, and the high consistency among surveillance video records as well as the on-site disaster trace distributions, and wind field evolution, which verified the synergistic disaster-causing chain of dynamic – thermal – microphysical coupling in this case. This study fills the gap in multi-source data fusion analysis of the multi-factor synergistic disaster-causing mechanism of wet microbursts, and provides vital scientific support for the optimization of early warning and emergency response to similar water vessel capsizing disasters.