吴亚丽,蒙伟光,陈德辉,林文实,朱立娟. 2018. 一次华南暖区暴雨过程可预报性的初值影响研究[J]. 气象学报, 76(3):323-342, doi:10.11676/qxxb2018.001
一次华南暖区暴雨过程可预报性的初值影响研究
A study of the impact of initial conditions on the predictability of a warm-sector torrential rain over South China
投稿时间:2017-05-18  修订日期:2017-11-05
DOI:10.11676/qxxb2018.001
中文关键词:  暖区暴雨  初值  对流触发  对流维持
英文关键词:Warm-sector torrential rain  Initial conditions  Convection triggering  Convection maintenance
基金项目:国家自然科学基金(41675099、41705035)、广东省科技计划项目(2017A020219005)、广州市科技计划项目(201604020012)。
作者单位E-mail
吴亚丽 区域数值预报重点实验室/中国气象局广州热带海洋气象研究所, 广州, 510080
中山大学大气科学学院, 广州, 510275 
 
蒙伟光 区域数值预报重点实验室/中国气象局广州热带海洋气象研究所, 广州, 510080  
陈德辉 区域数值预报重点实验室/中国气象局广州热带海洋气象研究所, 广州, 510080
国家气象中心/数值预报中心, 北京, 100081 
chendh@cma.gov.cn 
林文实 中山大学大气科学学院, 广州, 510275 linwenshi@mail.sysu.edu.cn 
朱立娟 国家气象中心/数值预报中心, 北京, 100081  
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中文摘要:
      华南暖区暴雨发生时,冷空气和锋面离广东较远,往往事前不易被发现,漏报或迟报较多。基于覆盖华南区域的3 km GRAPES_Meso模式和ADAS (ARPS Data Analysis System)系统的复杂云分析方案,选取2015年5月16日发生在粤西沿海地区的一次暖区暴雨个例进行数值试验,研究模式初始湿度条件的差异对暖区对流系统的触发、发展和维持的可预报性的影响。试验结果表明,增加模式的初始云信息可以增大初始场中低层的大气湿度,使空气接近或达到饱和,从而使数值模式有能力模拟出与实况接近的降水。分析模拟结果的对流触发和维持过程,可以发现,(1)初始水汽和云水物质的增多,增大了大气的不稳定性:对流有效位能(CAPE)增大、K指数增大,对流抑制能量(CIN)减小、抬升指数(LI)减小,而且大气可降水量(PW)增多,从而使对流能够被快速激发;(2)暖区暴雨对流触发和对流维持的机制有所不同:模式对初始时刻湿度条件高度敏感,模式开始积分后饱和大气释放凝结潜热加热大气,所导致的浮力增强使对流更容易被触发;对流维持发展阶段,降水引发地面弱冷池形成,冷池向外流出气流与粤西沿海暖湿气流的汇合维持了低层水平风场辐合,从而维持了对流和降水的发展。进一步的敏感性试验表明,减少初始水汽增量,则辐合上升运动减弱,激发的对流强度减弱,且对流发生、发展、消散的速度变慢、滞后于实况。
英文摘要:
      The warm-sector torrential rain in South China often occurs in the warm sector 200-300 km ahead of a cold front or without a cold front. Because of the lack of distinct synoptic systems, the predictability of this type of rain is at a very low level. To discuss the impact of initial moisture condition on warm-sector convection triggering and development, two numerical experiments (the control run CTRL and the cloud analysis run CLD) are designed to study a case occurred over the western coast of Guangdong province on 16 May 2015. These experiments are conducted using 3-km resolution mesoscale GRAPES (Global/Regional Assimilation and PrEdiction System) model and ADAS (ARPS Data Analysis System) complex cloud analysis system. Results show that:(1) the initial condition of cloud analysis run CLD is characterized by higher moisture content, more instable stratification, larger convective available potential energy, increased K index and precipitable water, and lower lifting condensation level and convective inhibition, and smaller LI index. Thereby the vertical velocity is enhanced and the convection is triggered more quickly; (2) there exist some differences between the mechanisms for the warm-sector convection triggering and development, i.e., the triggering is enhanced by latent heat released from water vapor condensation, which contributes to the positive buoyancy; during the convection development period, convergence is caused by the outbreak of the surface cold pool and the warm advection from the sea. Sensitivity experiments further indicate that when reducing the water vapor content to 70%, the initial convergence is weakened, and the convection triggering is subsequently weakened, while the dissipation is also delayed. These results can increase our understanding of the predictability of warm-sector torrential rain in South China. Specifically, results of the present study can be used as a reference for future development of operational cycling assimilation system.
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