合肥市21·7暴雨水汽输送过程与特征解析

Analysis of the water vapor transport process and characteristics of the rainstorm in Hefei in July 2021

摘要

【目的】全球气候变化的背景下，气候变率陡增，极端事件频发，对人民生命财产和社会经济健康发展带来巨大威胁。2021年安徽省梅雨期平均降雨量317 mm,较常年同期偏丰近三成。为分析暴雨水汽输送场，揭示其发展过程特征。【方法】基于拉格朗日混合单粒子轨迹模型(HYSPLIT)计算了2021年7月合肥市董铺、大房郢水库流域场次降雨期间水汽输送轨迹。【结果】结果显示：降雨量空间分布不均匀，平均降雨量为306.6 mm,刘庙站的降雨量最高(356.5 mm),而最低的是沈油坊站(228.5 mm);不同高度层的水汽输送轨迹特征存在差异，925 hPa有西太平洋的东南路径、孟加拉湾的西南路径、中国南海的南向路径，对应的水汽贡献率分别为44.4%、43.8%、11.8%;850 hPa有西太平洋路径和孟加拉湾路径，分别为26.3%、73.7%;700 hPa有西太平洋路径、印度洋的西南路径、青藏高原的西向路径，分别为17.1%、77.9%、5.0%;随着水汽轨迹模拟的初始高度增加，水汽轨迹数目的空间分布表现为西多东少，且温度和比湿度在输送过程中均发生了增加(减少)。【结论】2021年7月合肥市董铺、大房郢水库流域场次降雨在不同高度层上的水汽均主要来源于海洋通道，尤其是来自西太平洋、孟加拉湾和印度洋的水汽贡献为主。而在850 hPa高度层上，出现了非常强烈的水汽辐合带，为局部短时强降雨供应着充沛的水汽。

Abstract

[Objective] In the context of global climate change, climate variability has increased sharply, and extreme events have become more frequent, posing significant threats to people's lives, property, and the healthy development of the socio-economic system. During the 2021 Meiyu season in Anhui Province, the average rainfall was 317 mm, which was nearly 30% higher than the long-term average. To analyze the moisture transport field of heavy rainfall and reveal its development characteristics, [Methods]the Lagrangian Hybrid Single Particle Trajectory Model(HYSPLIT) was utilized to simulate the moisture transport trajectories during the rainfall event in the Dongpu and Dafangying reservoir basins of Hefei City in July 2021. [Results] The result indicate that the spatial distribution of rainfall was uneven, with an average rainfall of 306.6 mm. The highest rainfall was recorded at Liumiao Station(356.5 mm), while the lowest was at Shenyoufang Station(228.5 mm). The characteristics of moisture transport trajectories varied at different height levels. At 925 hPa, there were southeast paths from the Western Pacific, southwest paths from the Bay of Bengal, and southward paths from the South China Sea, with corresponding moisture contribution rates of 44.4%, 43.8%, and 11.8%, respectively. At 850 hPa, the paths from the Western Pacific and the Bay of Bengal accounted for 26.3% and 73.7%, respectively. At 700 hPa, the paths included the Western Pacific, southwest paths from the Indian Ocean, and westward paths from the Tibetan Plateau, with contributions of 17.1%, 77.9%, and 5.0%, respectively. As the initial height of the moisture trajectory simulation increased, the spatial distribution of the number of trajectories showed a pattern of more in the west and less in the east, and both temperature and specific humidity increased(decreased) during the transport process. [Conclusion] The moisture for the rainfall event in the Dongpu and Dafangying reservoir basins of Hefei City in July 2021 primarily originated from oceanic channels at different height levels, with significant contributions from the Western Pacific, the Bay of Bengal, and the Indian Ocean. At the 850 hPa level, a very strong moisture convergence zone was observed, providing ample moisture for localized heavy rainfall.

关键词

董大水库 / 降雨 / HYSPLIT / 水汽输送 / 水汽通量散度 / 气候变化 / 时空分布

Key words

Dongpu and Dafangying Reservoirs / rainfall / HYSPLIT / water vapor transport / water vapor flux divergence / climate change / spatiotemporal distribution

基金资助

国家自然科学基金项目(42377346)

陕西省自然科学基础研究计划联合基金项目(2022JC-LHJJ-01)