| 摘要: |
| 【目的】分析滇西北横断山脉2020年5月24—27日持续性强降水天气过程特征和成因。【方法】利用ERA5再分析资料和怒江州气象观测站雨量数据，基于HYSPLIT模式及天气学诊断分析。【结果】（1）中高纬环流的调整使南支槽稳定在青藏高原南部，上游风速增大使中高层形成西风急流，低层西南气流辐合，93～98°E、26～28°N区域维持大于20 m·s-1的纬向风且扩大东移。（2）贡山站过程累积雨量历史排行第二，暴雨持续日数达历年最高，具有一定的极端性。最大小时雨量9.9 mm，长时间降水的维持是引起此次过程的重要条件。（3）过程期间大气低层强辐合、中高层强辐散，抽吸作用明显，降水强盛期前97～99°E区域低层强辐合中层强辐散中心与强降水落区相对应，中高层上升气流加强时期与降水集中时段对应较好，物理量的变化对降水趋势变化有指示意义。（4）低层水汽辐合强且向中高层输送，大于90%的相对湿度伸展至高层。水汽主要来源于孟加拉湾及阿拉伯海，部分水汽来自喇叭口地形作用及天气系统。【结论】加深对此类过程的了解和认识，为开展预报预警服务提供参考。 |
| 关键词: 持续性强降水；南支槽；西风急流；水汽来源 |
| DOI： |
| 投稿时间：2023-03-25修订日期：2024-01-28 |
| 基金项目:云南省气象局基层台站气象科技创新与能力提升计划项目（STIAP202253） |
|
| Characteristics and Causes of a Continuous Heavy Rainfall Process in Hengduan Mountains, Northwest Yunnan Province |
| xiaojinyi,DI Aisong |
| (Meteorological Bureau of Gongshan County) |
| Abstract: |
| The characteristics and causes of the continuous severe precipitation process that occurred in the Hengduan Mountains of northwest Yunnan Province from May 24 to 27, 2020 are analyzed based on the ERA5 reanalysis data and precipitation data from Nujiang Meteorological Station as well as the HYSPLIT model and synoptic diagnostic analysis method. The results suggest that: (1) During this continuous severe precipitation process, the south branch trough stabilized in the south of Qinghai-Tibet Plateau due to the adjustment of atmospheric circulation in the middle to high latitudes. The increased wind speed from the upwind area caused westerly jet to come into being in the upper atmosphere and southwest airflow to converge in the lower atmosphere. The 93-98° E, 26-28° N area maintains latitudinal winds greater than 20 m·s-1 and expanding eastwards. (2) The accumulated precipitation in the process at the Gongshan Meteorological Station ranked the second in records, and the maximum number of continuous torrential rain days was extreme. The maximum hourly rainfall reached 9.9 mm, and the long duration was an important feature in this severe precipitation process. (3) During the severe precipitation process, it was noticeable that there was strong convergence in the lower atmosphere and strong divergence in the middle and upper atmosphere, so the effect of air suction was obvious. Before the period of heavy precipitation, the centre of strong low-level convergence and strong mid-level dispersion in the 97-99° E region corresponds to the area of heavy precipitation, and the period of intensification of mid- and upper-level updrafts corresponds well to the period of concentrated precipitation. Moreover, the variation of physical parameter indicated the changing trend of precipitation. (4) On account of the moisture transport from the lower to the upper atmosphere, the relative humidity higher than 90% extended to the upper atmosphere. The moisture mainly originated from the Bay of Bengal and the Arabian Sea, with some moisture from the trumpet topography and synoptic systems. The finding of this research can deepen the understanding of such process and provide references in the forecasting and warning services. |
| Key words: continuous heavy precipitation; south branch trough; westerly jet; source of moisture |
