| 高原低值系统影响下一次极端强降水天气诊断分析 |
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| 引用本文： | 杨康权,卢萍,肖递祥,等.高原低值系统影响下一次极端强降水天气诊断分析[J].高原山地气象研究,2017,37(2):1-7. |
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| 作者姓名： | 杨康权 卢萍 肖递祥 等 |
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| 作者单位： | 1. 四川省气象台/高原与盆地暴雨旱涝灾害四川省重点实验室, 成都 610072; |
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| 基金项目： | 中国气象局预报员专项项目(CMAYBY2014-062,CMAYBY2017-062)资助国家自然科学基金重点项目(91337215)国家重点基础发展计划项目(2012CB417202) |
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| 摘 要： | 采用常规观测资料、地面加密观测资料、逐时云顶亮温TBB资料和1°×1°NCEP/NCAR再分析资料,对2013年7月8~11日四川盆地持续性暴雨天气过程的中尺度对流系统活动及其发生发展的物理机制进行了分析。结果表明:(1)暴雨过程发生在对流层中层中高纬度两槽一脊稳定维持的环流背景下,由活跃的高原低值系统以及异常稳定的副高西侧偏南气流配合低层冷空气作用造成。(2)极端降水过程分为暖区强对流性降水和相对稳定的锋面降水两个阶段;暖区对流性降水阶段,偏南暖湿气流源源不断向盆地输送水汽和能量,为暴雨发生提供了高能高湿条件,大气层结极不稳定,中尺度对流云团发展旺盛;锋面降水阶段层结趋于稳定,对流云团有所减弱,但仍有充足的水汽输送且降水云系稳定少动,致使盆地西部产生持续性降水。(3)500h Pa高原低槽前的正涡度平流诱发盆地西部低层气旋性涡度增加、低涡生成和发展,致使暖湿气流持续在盆地西部形成辐合上升,为暴雨的维持提供了很好的动力条件,两个降水阶段均为明显的低层辐合高层辐散的特征,暖区对流性降水阶段正涡度发展较锋面降水阶段更强。(4)青藏高原东侧的地形作用强迫气流在盆地西部强烈辐合上升,使得暖湿水汽更加有效率地形成降水,是此次极端强降水天气出现的一个重要动力因素。
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| 关 键 词： | 极端暴雨 中尺度对流系统 涡度平流 地形作用 |
| 收稿时间： | 2017-04-13 |
Impact of the Low-Pressure System of Qinghai-Xizang Plateau on the Occurrence and Maintenance of Extreme Heavy Rainfall Event |
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| Affiliation: | 1. Sichuan Meteorological Observatory/Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province, Chengdu 610072, China;2. Institute of Plateau Meteorology, CMA/Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province, Chengdu 610072, China;3. Jintang Meteorological Bureau, Jintang 610400, China;4. Meishan Meteorological Bureau, Meishan 511400, China |
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| Abstract: | An analysis of the mesoscale convective system in a persistent heavy rain event during 8 to 11 July 2013 in Sichuan basin is performed by using of the routine observational data、ground intensive observational data、FY-2E satellite observational data and NCEP/NCAR 1°×1° reanalysis data.It is found that: (1) The heavy rainfall occurs in the stable circulation of two trough and a ridge, then caused by active plateau systems、the exceptionally stable subtropical anticyclone with a southerly jet and the low-level cold air. (2) This extreme precipitation process is composed by a warm-area mesoscale-feature precipitation stage and a relatively stable frontal precipitation stage. Adequate energy and moisture is delivered by a southerly jet to the rainfall area in the stage of warm-area precipitation, and it provides a high-energy and high humidity condition for the mesoscale convective systems happen and development; The energy dissipate and the convective systems subside in the stage of frontal precipitation, but enough water vapor is delivered to the basin make the rainfall continued. (3) The south-west vortex is induced by the positive vorticity advection of 500 h Pa upper trough, it will make the warm-humid air continues to rise in the western basin that provides for the maintenance heavy rainfall a good dynamic condition, and the characteristic of low convergence-high divergence is found in the two precipitation stage and vorticity develop more stronger in the stage of warm-area precipitation. (4) The terrain of the Tibetan Plateau force airflow strongly convergence to rise in the western basin that makes warm water vapor more efficient formats precipitation is an important factor in the extreme precipitation process. |
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