第八届全国中尺度气象学研讨会

Warm-season extreme rainfall over the eastern Tibetan Plateau is strongly influenced by water-vapor transport, but the largest instantaneous moisture forcing does not always lead to the largest event-total precipitation. This study addresses why a short pulsed event can exhibit stronger high-end moisture transport and convergence than a longer event while producing less accumulated rainfall. Two selected cases are compared: a persistent rainfall event during 17–26 August 2021 and a pulsed rainfall event during 23–27 June 2022. Daily precipitation from CN05.1, European Centre for Medium-Range Weather Forecasts Reanalysis version 5 (ERA5), Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG), Weather Research and Forecasting model (WRF) rainfall output and precipitation-adjusted forcing checks are combined to diagnose moisture transport, moisture-flux convergence, convective instability, vertical motion, precipitation partitioning and precipitation conversion. The 2021 event was characterized by more persistent moisture-flux convergence, larger convective available potential energy, a higher ERA5-derived convective precipitation fraction and higher precipitation efficiency relative to column water vapor. The 2022 event instead had slightly larger precipitable water and stronger high-end integrated vapor transport and moisture-flux convergence, but the overlap among moisture inflow, convergence, ascent and active precipitation was shorter. The comparison suggests that, in these two cases, accumulated rainfall was more closely associated with the residence time and co-location of the conversion environment than with peak moisture forcing alone. Single-scale terrain-smoothing experiments provide auxiliary process context, but the findings remain a two-case atmospheric diagnosis rather than a formal terrain-attribution analysis or regional climatology.