一次飑线内MVs和后向入流与地面大风发生的成因分析 及模拟研究
投稿时间: 2017-07-04  最后修改时间: 2017-08-18  点此下载全文
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作者单位E-mail
赵向军 南京信息工程大学大气科学学院 iamzxj841025@163.com 
丁治英 南京信息工程大学大气科学学院 dingzhiying@nuist.edu.cn 
阿不都外力.阿不力克木 新疆大学资源与环境科学学院  
王瑾婷 南京信息工程大学大气科学学院  
刘瑾 南京信息工程大学大气科学学院  
基金项目:国家重点基础研究发展项目规划“973”( 2013CB430103);中国气象局国家重点灾害实验室 (2015LASW-A07);国家自然科学基金重点项目(41530427);国家自然科学基金(41375058)
中文摘要:通过实况资料以及WRF模式对广西地区的一次飑线过程进行数值模拟,根据模拟结果对飑线内MVs和后向入流与地面大风的成因关系进行了分析。通过涡度收支和涡线分析得出,弓状回波中存在东西涡旋对,其生成主要是散度项造成的,中间相对弱的反气旋涡旋是涡线的拱起产生的水平涡度向垂直涡度转换引起。通过计算正负涡旋对引起的旋转风从而量化了涡旋对对地面大风的贡献。结果发现,本次过程中涡旋对引起的旋转风在地面大风中占有较大比重,约40%-50%。当去除涡旋对引起的旋转风时,地面大风的强度减弱,位置偏移。由三维流线可以看出后向入流的下沉是产生地面大风的另一个影响因子。通过对浮力加速度和动力加速度进行诊断发现,后向入流的下沉主要是由于负的浮力加速度引起,水平方向的密度不均匀是负浮力加速度产生的主要因子,但在风速突然加强时,动力加速度也有明显的影响。
中文关键词:MVs  后向入流  涡线  旋转风  地面大风
 
The cause analysis and simulation study of MVs and rear inflow in a squall line with the occurrence of surface high winds
Abstract:Through the WRF model and observational data, the numerical simulation was proceed for a squall line process occured in guangxi region. Based on the simulation results, the relationship of the MVs and the rear inflow in the squall with the surface high winds are analyzed. The Vorticity Budget and the analysis of vortex line show that there are east-west vortex couplet in the bow echo, which are mainly caused by the divergence term, and the middle relatively weak anticyclone vortex is generated due to the conversation of horizontal vorticity to vertical vorticity caused by the arch of vortex line. The contribution of couplet of vortex to the high winds on the ground is quantified by calculating cyclostrophic wind caused by the couplet of vortex. The results show that the cyclostrophic winds account for 40% -50% of the ground winds in this squall line process. When the cyclostrophic winds are removed, the intensity of the surface high winds will be weakened and the position will be shifted. It can be seen from the three-dimensional streamline that the subsidence of the rear inflow is another factor that produces the surface high winds. Through the diagnosis of the buoyancy acceleration and dynamic acceleration, it is found that the sink of rear inflow jet is caused by the buoyancy acceleration. The uneven density in the horizontal direction is the main factor of generating the negative buoyancy acceleration, but the dynamic acceleration also has obvious effect when the wind speed is suddenly strengthened.
keywords:MVs  the rear inflow  vortex line  the cyclostrophic wind  the surface high winds
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