| 四川盆地暖区暴雨的雷达回波特征及分类识别 |
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| 引用本文： | 罗辉,肖递祥,匡秋明,青泉,康岚.四川盆地暖区暴雨的雷达回波特征及分类识别[J].应用气象学报,2020,31(4):460-470. |
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| 作者姓名： | 罗辉 肖递祥 匡秋明 青泉 康岚 |
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| 作者单位： | 1.四川省气象台, 成都 610072 |
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| 摘 要： | 暖区暴雨强度大且降水集中，可造成严重气象灾害。利用四川盆地实况降水和7部天气雷达资料，分析了2012—2017年28次暖区暴雨过程的降水特征，按超过20 mm·h-1降水站数的突增，将暖区暴雨的雷暴群分为初生阶段和成熟阶段，根据不同降水类型成熟前后的雷达回波特征，将雷暴群分为3种类型，3类回波特征差异明显，雷暴的长时间生消、合并以及传播作用使暖区暴雨降水强度大、范围广。在28次暖区暴雨过程中，四川盆地西北部出现次数最多，持续时间最长，回波基本呈现东北—西南向，与四川盆地西部龙门山脉走向基本一致，地形（产生偏东风）抬升在暖区暴雨的发生发展中起关键作用。对3类雷暴群质心高度、顶高、最大回波强度等要素的统计显示，不同类型雷暴群在初生阶段和成熟阶段的概率密度曲线存在双峰和单峰等结构特征。利用雷暴群的多个参数构建暖区暴雨分类识别的特征向量，并采用随机森林机器学习方法进行识别，取得较好效果。
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| 关 键 词： | 暖区暴雨 雷暴群 回波特征 随机森林 |
| 收稿时间： | 2019-10-10 |
Radar Echo Characteristics and Recognition of Warm-sector Torrential Rain in Sichuan Basin |
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| Institution: | 1.Sichuan Meteorological Observatory, Chengdu 6100722.Heavy Rain and Drought-Flood Disaster in Plateau and Basin Key Laboratory of Sichuan Province, Chengdu 6100723.CMA Public Meteorological Service Centre, Beijing 100081 |
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| Abstract: | Based on data of real-time precipitation and weather radar during 28 torrential rain events in warm regions of Sichuan Basin, radar echo characteristics of torrential rain in early and mature stages are analyzed. Feature vectors for identifying early and mature stages of torrential rain in warm regions are constructed and the selected samples are studied by random forest machine learning method. According to the influence range, duration, and cumulative amount of precipitation, the thunderstorm group is the main part of the rainstorm in the warm region, and its development can be divided into three types.According to the burst of short-term heavy precipitation, thunderstorm groups are divided into primary and mature stages. In the early stage of the thunderstorm to the mature stage, the "in situ development type" is dominant, the "individual development type" and the "in front side trigger type" are the second. With the evolution after the maturity, the "in situ development type" and the "front side trigger type" are the main types. Convective precipitation is the main type of heavy rain in the warm area. After the first type of thunderstorm group, the combination of mature thunderstorms is the main source of thunderstorms, which moves slowly and is conducive to the generation of heavy precipitation. In front of mature thunderstorms, new thunderstorm cells are continuously generated and merged to continue spreading northward, forming a large range of precipitation. Individual development thunderstorm groups have the longest duration and a large influencing range. They are accompanied by long-term merge when moving. Among 28 processes, a large proportion appears in the northwest and has the longest duration. Echoes of these processes are in the southwest-northeast direction, which is basically consistent with the trend of the Longmen mountains in the western part of the Basin. The uplift of the topography (generating easterly wind) plays a key role in the occurrence and development of warm rainstorms. In the primary stage, the average core height and average top height of "in situ development type" thunderstorm group has a bimodal structure. Similar structure is found for "front side trigger type" in the mature stage. Multiple parameters of three types of thunderstorm groups show a unimodal distribution in the nascent and mature stages. To identify heavy rains in the warm area, feature vector is constructed using multiple parameters of the thunderstorm group, and random forest machine learning is also applied, leading to satisfying results. |
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