下垫面对郑州城市强降水的影响:城市化及地形 影响的数值模拟研究
投稿时间:2018-11-16  修订日期:2019-01-20  点此下载全文
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作者单位E-mail
苏爱芳 1.中国气象局(河南)农业气象保障与应用技术重点实验室
2.河南省气象台 
610061618@qq.com 
施东雷 南京信息工程大学  
葛旭阳 南京信息工程大学  
基金项目:河南省科技攻关项目《大城市暴雨、强对流精细预报与监测预警技术研究》(162102310056)
中文摘要:利用WRF-ARW中尺度区域数值模式耦合单层城市冠层模式(slab-UCM),采用ERA-interim 0.5°× 0.5°再分析资料作为初始场和边界条件,对2016年6月5日郑州地区发生的一次强对流天气进行模拟,并通过改变下垫面的土地利用类型与地形高度数据设置敏感性试验,探究了城市化及郑州西北部山脉地形对对流性强降水过程的影响。结果表明:(1)此次强降水过程主要受高层的低槽系统影响,前期的对流不稳定层结为对流触发提供了有利的热力条件;(2)城市热岛效应能够改变下垫面的热力状况,有利于在城市地区激发更强的上升运动,使降水向城区集中;(3)郑州西北侧山脉激发的重力波能够使郑州地区对流增强;(4)山脉能够阻挡低层干空气向郑州地区输送,因此山脉高度的削减造成郑州地区低层相对湿度减小,使雨滴蒸发冷却增强,进而导致与降水相联系的冷池的增强,雨带移速加快,进一步导致累积降水的减少。
中文关键词:数值模拟  强对流  城市热岛  地形作用
 
Numerical Simulation of the Influence of the Urbanization and Orography on a Severe Rainfall Event in Zhengzhou
Abstract:Based on the 0.5° × 0.5° ERA-interim reanalysis data, a heavy rainfall event that occurred on 5 Jun 2016 in Zhengzhou was simulated using the Advanced Research Weather Research and Forecasting Model (WRF-ARW) coupled with a slab urban canopy model (UCM). Sensitivity experiments with the modified land-use categories and terrain height are conducted to investigate the impact of urbanization and topography of the mountain to the northwest of Zhengzhou on the heavy rainfall. The conclusions are summarized as follows: (1) The severe rainfall are mainly induced by the favorable conditions associated with an upper-level trough and the convective unstable stratification; (2) The effect of urban heat island tends to enhance upward motion and thus convection in the urban area, which makes the precipitation more concentrating in the city; (3) The gravity wave excited by the orographic effect can promote the convection in Zhengzhou region; (4) The mountain to the northwest of Zhengzhou can hamper the northward transport of the low-level dry air. Therefore, the cut of the mountain height can lower the relative humidity in Zhengzhou region, which enhance the evaporation cooling and thus the cold pool associated with the precipitation. The strong cold pool helps the rainband to move fast, which further reduces the total rainfall.
keywords:Numerical simulation  Severe convection  Urban heat island  Orographic effect
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