江淮地区夏季夜间高架对流触发及伴生地面对流的机制研究

The elevated and surface-based convection which is the direct system triggering the severe convective weather, occurs frequently during the night in the summertime over the Yangtze-Huaihe river basin (YHRB). Therefore, the initiation of elevated and surface-based convection and the mechanism of their interaction are regarded as the key scientific issues. This project plans to reveal the characteristics of the nocturnal convection initiation (CI) during the summertime over the YHRB on the basis of the observational data, and conduct a mechanism study on the nocturnal elevated CI and concomitant initiation process of the surface-based convection by utilizing the numerical experiments. The main contents include: (1) to analyze the basic features of the nocturnal CI, such as the initiation time, location, storm types, severe events and propagation, according to the satellite data and radar data; (2) to explore the traits of the convergence zones and discuss the role of convergent forcing in the CI by using the surface data and radar data; (3) to investigate the mechanism of the environment forcing and the interaction between convective systems during the elevated CI process and concomitant initiation of the surface-based convection by employing the high-resolution numerical experiments.

江淮地区夏季的高架对流和地面对流常在夜间发生，是触发突发性强对流天气的直接系统。因此，高架对流和地面对流的触发及其相互作用机制是一个重要的科学问题。本项目拟基于观测资料揭示江淮地区夏季夜间对流触发特征和机理，利用数值模拟开展高架对流触发及伴生地面对流的机制研究。主要内容包括：（1）利用卫星资料和雷达资料分析夜间对流触发的基本观测特征，包括触发的时刻、位置、风暴类型、天气现象和对流触发后的移动等；（2）利用地面资料和雷达资料分析辐合线特征并探讨辐合强迫在夜间对流触发中的作用；（3）采用高分辨率的数值模拟，研究高架对流的触发及其发展中激发地面对流的环境强迫和对流系统之间相互作用的机制。

江淮地区夏季对流常在夜间发生，是触发突发性强对流天气的直接系统。本项目首先利用雷达拼图资料，提取了2017-2018年夏季（5-8）月我国江淮地区对流触发的样本，分析了对流触发的基本特征（时间、位置及触发机制）；之后基于2005-2019年2-10月FY2静止卫星资料，识别和追踪了不同类型的中尺度对流系统，统计分析了不同类型中尺度对流系统的时空分布、日变化、移动路径、云顶亮温和面积变化，并与对应位置和时间段内的降水系统进行了比较分析；接着用逐时的格点降水资料获取了我国华南地区极端持续性降水的样本，统计了其基本特征；最后用高分辨率的数值模式研究了梅雨锋期间，边界层对流卷对持续性对流触发的作用。