Understanding frontal clouds and precipitation is crucial due to its increasing variability and intensity driven by global warming, which impacts agriculture, water resource management, and climate adaptation. Autumn precipitation in Central China is frequently induced by extratropical cyclones, often featuring a frontal cloud system influenced by warm conveyor belt (WCB). In this paper, the detailed microphysical processes of an autumn precipitation event were examined using reconstructed vertical profiles of polarimetric variables, supplemented with numerical simulation to better depict the microphysics evolution in different stages. Results showed that during the initial stage, a strong, inclined updraft and supersaturated layer influenced by WCB, enhanced the formation and depositional growth of ice particles above −10 °C level, then ice particles grew by riming in addition to aggregation in −5–0 °C layer while precipitation particles coalescence and collecting cloud droplets occurred in warm cloud. As the vertical extent of supersaturated layer increased, the intensified process of collecting cloud droplets and vigorous riming process contributed to the maximum surface rainfall intensity. In the weakening stage, ice-phase processes attenuated before the warm cloud processes showed reducing tendencies. This decline is attributed to weakened inclined updraft and supersaturated layer falling below 0 °C level, which impaired the conditions necessary for ice-phase processes. It is concluded that the thermodynamic structure of WCB, namely the vertical extension of inclined updraft and the presence of supersaturated layer, significantly influenced both the ice-phase and liquid-phase microphysical processes of the frontal cloud system as well as the surface precipitation.

中文翻译：

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华中地区暖输送带影响秋季锋面云微物理过程研究


了解锋面云和降水至关重要，因为全球变暖导致其可变性和强度不断增加，这会影响农业、水资源管理和气候适应。华中地区的秋季降水经常由温带气旋诱发，通常以受暖传送带 （WCB） 影响的锋面云系统为特征。在本文中，使用重建的极化变量垂直剖面研究了秋季降水事件的详细微物理过程，并辅以数值模拟，以更好地描述不同阶段的微物理演变。结果表明，在初始阶段，受 WCB 影响的强烈倾斜上升气流和过饱和层促进了 −10 °C 以上冰颗粒的形成和沉积生长，然后冰颗粒在 −5–0 °C 层中除了聚集外，还通过边缘生长，而降水颗粒聚结和收集云滴发生在暖云中。随着过饱和层垂直范围的增加，云滴收集过程的加强和剧烈的边缘化过程导致了最大的地表降雨强度。在减弱阶段，冰相过程在暖云过程之前减弱，表现出减少趋势。这种下降归因于倾斜上升气流减弱和过饱和层降至 0 °C 以下，这损害了冰相过程所需的条件。结论是，WCB 的热力学结构，即倾斜上升气流的垂直延伸和过饱和层的存在，显着影响了锋面云系统的冰相和液相微物理过程以及地表降水。