| 2012年庆阳市一次短时大暴雨的诊断 |
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| 引用本文： | 路亚奇,王建,焦美龄.2012年庆阳市一次短时大暴雨的诊断[J].甘肃气象,2013(3):542-549. |
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| 作者姓名： | 路亚奇 王建 焦美龄 |
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| 作者单位： | [1]中国气象局兰州干旱气象研究所,甘肃省干旱气候变化与减灾重点实验室,中国气象局干旱气候变化与减灾重点开放实验室,甘肃兰州730020 [2]甘肃省庆阳市气象局,甘肃庆阳745000 |
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| 基金项目： | 甘肃省气象局科研项目“基于配料法的甘肃河东短时强降水短期预报方法研究（201305）”资助 |
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| 摘 要： | 庆阳市2012年7月21日区域性大暴雨创造了环县1957年建站以来的历史极值，导致了人民财产的重大损失。本文利用常规资料、自动站等探测资料以及历史相似个例，对2012年7月21日庆阳市出现的区域性大暴雨天气进行分析。结果表明：（1）高空低槽伴随地面冷锋东移，受西太平洋副热带高压的阻挡移动缓慢，副高、大陆高压不断加强，造成贝加尔湖冷空气在两高之间大量堆积，为这场大暴雨发生奠定了基础；（2）2012年第8号台风“韦森特”登陆前，台风低压和副热带高压之间形成的强气压梯度导致通向庆阳市的南风低空急流建立并加强，为此次大暴雨的发生提供了充分的水汽条件；（3）在高空槽前正涡度平流的作用下，对流层中低层出现明显的辐合，产生强烈上升运动，低层暖湿气流抬升促使对流不稳定能量爆发，从而形成局地强对流和暴雨；（4）导致庆阳区域性大暴雨的中尺度对流系统起源于河套地区低层涡旋的发展，在中尺度涡旋向东北和向东扩展过程中，尺度明显增大，整个系统低层具有明显的气旋性切变和气旋性涡度，在有利的环境条件下整个中尺度对流系统的东移和发展壮大，最终导致庆阳市区域性大暴雨的发生。
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| 关 键 词： | 大暴雨 低空急流 中小尺度系统 台风远距离影响 庆阳市 |
Diagnostic Analysis on the Short- term Cloudburst in Qingyang of Gansu Province on July 21, 2012 |
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| LU Yaqi,WANG Jian,JIAO Meiling.Diagnostic Analysis on the Short- term Cloudburst in Qingyang of Gansu Province on July 21, 2012[J].Gansu Meteorology,2013(3):542-549. |
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| Authors: | LU Yaqi WANG Jian JIAO Meiling |
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| Institution: | 1. Lanzhou Institute of Arid Meteorology, CMA, Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province, Key Open Laboratory of Arid Climatic Change and Disaster Reduction, CMA, Lanzhou 730020, China; 2. Qingyang Meteorological Bureau of Gansu Province, Qingyang 745000, China) |
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| Abstract: | The regional cloudburst in Qingyang on July 21, 2012 was the most severe rainfall event since the meteorological station of Huanxian County was established in 1957, which resulted in a significant property loss and people casualty. Thus, based on the con- ventional data from the automatic station and the historical similar cases of cloudburst, detailed analysis and investigation were carried out in this paper. The results are as follows ： accompanied with the surface cold front moving eastward, the speed of the upper - level trough blocked by the west Pacific subtropical high was slowed down, and the cold air over Lake Baikal was abundantly accumulatedat between two high pressures, which established the foundation for the severe rainstorm process. Before the typhoon ＂Vicente＂ landing, due to the presence of the strong pressure gradient between typhoon depression and subtropical high, the southward low - level jet lead- ing to Qingyang area was established and enhanced, which provided a plenty of water vapor for the cloudburst. Under the influence of positive vortieity advection in front of the upper trough, there was obvious subtropical convergence in the middle and lower troposphere, which consequently formed violent ascending motion. The ascending motion of warm and humid air from the low - level triggered the ex- plosion of unsteady energy at the convection, and further formed local severe convection and heavy rain. At last, the mesoseale convec- tive systems that caused the regional cloudburst in Qingyang originated from the development of lower - level vortex in Hetao. When the mesoseale vortex moved to the east and northeast, its scale was distinctly enlarged and the lower - level of the whole system exhibited obvious cyclonic shear and cyclonic vorticity. Consequently, the eastern moving and enhancement of the entire mesoseale convective systems caused the regional cloudburst in Qingyang under suitable environment. |
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| Keywords: | cloudburst low - level jet stream meso - microscale systems long distance influence of the typhoon Qingyang |
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