飑线结构和强度对低层湿度和环境垂直风切变的敏感性研
投稿时间:2019-10-14  修订日期:2020-01-09  点此下载全文
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作者单位E-mail
高彦青 南京信息工程大学大气科学学院 489661266@qq.com 
马旭林 南京信息工程大学大气科学学院 xulinma@nuist.edu.cn 
孟泽华 南京信息工程大学  
程凯琪 南京信息工程大学  
基金项目:国家重点基础研究发展计划(973计划)
中文摘要:利用数值模式WRF进行二维飑线理想数值试验,通过改变初始场低层湿度和低层环境垂直风切变探讨了初始环境场对飑线在触发阶段与发展初期结构和强度的影响。低层湿度试验表明,增加低层湿度,有利于初始启动阶段对流的发生从而使对流系统强度更强;飑线强度增加,对流上升运动增强,更有利于冷池前沿激发出新生对流单体,系统发展更快;同时激发更多降水,冷池强度增强。低层环境垂直风切变试验表明,在飑线触发阶段,更强的环境垂直风切变使对流主体前倾趋势更大,对对流的触发有阻碍作用;冷池和环境垂直风切变的相互作用被认为是飑线发展的重要机制,基于RKW理论,在飑线发展初期,近地面冷池相对较弱,在更弱的环境垂直风切变作用下更容易使对流结构呈直立状态从而产生更强和更深的上升运动,飑线强度增强。
中文关键词:WRF  飑线  敏感性  低层湿度  垂直风切变
 
The Sensitivity of the structure and strength of squall line to low-level humidity and environmental vertical wind shear
Abstract:The sensitivity of the structure and strength of squall line in initial stage and early development stage to initial low-level humidity and environmental vertical wind shear is investigated in two-dimensional idealized squall line simulation with WRF model. The results of sensitivity test of low-level humidity indicate that increasing low-level humidity is favorable for convective triggering and stronger convective system. The increase of the squall line intensity and the enhancement of upward movement make it easier for new convective cells to form at the leading edge of the cold pool. Increasing low-level humidity leads to more precipitation. The intensity of the cold pool also increases with the precipitation increasing. The results of sensitivity test of low-level environmental vertical wind shear indicate that the convection is easier to become downshear tilted in initial stage with stronger low-level environmental vertical wind shear, which is unfavorable for convective triggering. The interaction between cold pool and low-level environmental vertical wind shear is considered as an important mechanism for the development of squall line based on RKW theory. In the early development stage of squall line, the cold pool is relatively weak. Under the weaker low-level environmental vertical wind shear, it is easier for the convection to become upright, resulting in stronger and deeper upward movement, which is conducive to the strength of squall line.
keywords:Numerical simulation, Sensitivity, WRF, Squall line, vertical wind shear
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