近60年我国华北地区夏季持续性暴雨过程的分类研究

Previous studies have obtained solid and abundant knowledge of the climatic background and circulation in understanding the persistent heavy rainfall events. Based on the synoptic analysis of extensive real weather events and rich experiences gained by forecasters, the persistent heavy rainfall events over North China in the summer (HX-PHRE) are analyzed and classified in this proposal from the perspective of the characteristics and interactions between the synoptic and sub-synoptic motions. The traditionally broadly-used quasi-geostrophic theory is reconstructed in the high-resolution numerical model with special considerations of the terrain effects and the diabatic heating. Firstly, daily precipitation data of relatively long series from 1958 to 2017 has been investigated. The HX-PHRE has been defined considering the unique characteristics of rainy season of North China, and then classified from the perspective of their dominant synoptic scale systems. The database of HX-PHRE in the last 60 years has been set up. Secondly, a set of diagnostic and prognostic equations under the approximation of quasi-geostrophic theory is derived in the numerical model's terrain-following coordinate system with the consideration of both the terrain effects and the diabatic heating. It is used for analyzing and partitioning the HX-PHRE database from the perspective of the characteristics and interactions between the synoptic and sub-synoptic motions. Last but not the least, the classification principle for HX-PHRE is concluded. This proposal combines mathematical tools and physical understandings, and has innovations both theoretically and technologically. Hopefully the results will help people with better understanding of the dynamics and improved numerical modeling skills.

本项目在已有关于持续性强降水过程气候变化及环流特征研究成果基础上，综合大量天气事实分析和台站预报员实践经验，在高分辨率数值模式中重新构建传统的准地转理论，补充考虑地形和非绝热影响，进一步理解华北地区夏季持续性暴雨过程（简称HX-PHRE）的动热力特征，从天气-次天气尺度系统特征及相互作用角度开展分类研究。具体研究内容有：（1）使用最近60年长序列的日降水量资料，结合华北雨季降水特点定义HX-PHRE，再从传统天气学分类角度，建立历史数据库。（2）在数值模式动热力框架上构建包括地形和潜热影响的准地转动力诊断-预报方法，针对每一类型从天气和次天气尺度系统发生发展特征和相互作用关系角度进行动热力分类。（3）总结归纳HX-PHRE动热力分类规则。本申请项目结合数学工具和物理本质，在理论和应用方面都有创新。研究成果既能提供动力理论和预报方法研究新思路，又能作为设计和改进数值模式和计算方法的理论基础。

本项目在已有关于持续性强降水过程气候变化及环流特征研究成果基础上，综合大量天气事实分析和台站预报员实践经验，在高分辨率数值模式中重新构建传统的准地转理论，补充考虑地形和非绝热影响，进一步理解华北地区夏季持续性暴雨过程（简称HX-PHRE）的动热力特征，从准地转近似下的天气-次天气尺度系统特征及相互作用角度开展分类研究。完成以下研究内容：（1）使用1958-2021年共64年的长序列日降水量资料，结合华北雨季降水特点定义HX-PHRE，从传统天气学分类角度，使用分级聚类方法，划分HX-PHRE为四种类型，最终建立历史数据库。（2）在数值模式动热力框架上构建包括地形和潜热影响的准地转动力诊断-预报方法，研发了针对不规则边界和复杂地形下垫面复杂流场的区域诊断分析技术、基于数值模式准地转动力理论的主导环流诊断分析技术、以及基于数值模式地形追随坐标系的水汽通量散度分解分析技术，对每一类型从天气系统发生发展特征和相互作用关系角度分析动热力特征。（3）总结归纳HX-PHRE动热力分类规则，应用到对几次极端HX-PHRE数值模拟中，并定量分析2021年两类主要的HX-PHRE的动热力特征及其可能的影响机制。本申请项目结合数学工具和物理本质，在理论和应用方面都有创新。研究成果既能提供动力理论和预报方法研究新思路，又能作为设计和改进数值模式和计算方法的理论基础，未来将从准地转近似提高至更高精度近似关系，应用于HX-PHRE业务预报。发表期刊论文13篇（其中SCI论文7篇），申请国家发明专利1项，出版科普书1本，培养5名研究生。