江苏近海岸夏季两类海风锋特征及其对强对流的激发
投稿时间:2017-01-03  修订日期:2017-07-22  点此下载全文
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苗春生 南京信息工程大学 气象灾害预报预警与评估协同创新中心, 江苏 南京 210044
南京信息工程大学 大气科学学院, 江苏 南京 210044 
 
张远汀 南京信息工程大学 大气科学学院, 江苏 南京 210044
北京华信空天科技有限公司, 北京 100081 
 
王坚红 南京信息工程大学 气象灾害预报预警与评估协同创新中心, 江苏 南京 210044
南京信息工程大学 海洋科学学院, 江苏 南京 210044 
1597706505@qq.com 
李洪利 南京信息工程大学 海洋科学学院, 江苏 南京 210044  
王兴 南京信息工程大学 大气科学学院, 江苏 南京 210044  
基金项目:国家自然科学基金资助项目(41276033);国家自然科学基金青年科学基金项目(41805033);江苏科技支撑项目(BE2014729);江苏校优秀学科建设工程项目(PAPD)
中文摘要:利用观测资料、ECMWF Era-interim资料、江苏风塔资料、降水融合资料等,对江苏沿海区域夏季海风锋进行统计与诊断分析,并对海风锋激发强对流过程进行数值模拟。结果显示,海风锋主要显现在较稳定的高压系统边缘地带,可分为两类:Ⅰ类为海上西伸副高控制下的海风锋;Ⅱ类为大陆高压入海环流下的海风锋,Ⅱ类海风锋环流具有更多局地系统,常有强对流天气伴随。海风锋垂直剖面要素结构显示,来自海上的低层偏东风u分量构成海风锋前缘,影响锋面垂直抬升运动位置及强度。锋面附近二级环流,影响海风锋系统的环境不稳定性。海风锋在近海岸地区相遇内陆对流系统时,沿岸风塔资料在风的时序上出现突然的风向转变和迅速的风速增大。同时区域对流有效位能CAPE(convective available potential energy)的高值区显著增强。配合水汽通量辐合中心,构成有利于强对流系统激发及加强的环境条件。数值模拟显示,CAPE的水平分布指示了内陆强对流系统与海风锋的相对移动,CAPE的垂直分布显示海风锋激发强对流时能量增强与释放,强中心在2 h内迅速减弱。
中文关键词:第Ⅰ类与第Ⅱ类海风锋  强对流激发  对流有效位能CAPE  激发过程数值模拟
 
Characteristics of two types of sea-breeze fronts along the coastal areas of Jiangsu Province and their triggers on strong convections
Abstract:This study analyzed the observational data;ECMWF Era-interim datasets;data of wind towers located along the Jiangsu coast line;assimilated precipitation data;sea/land breezes (SLB);and sea-breeze fronts (SBF) in the Jiangsu coastal regions,and the stimulating processes of the SBF for strong convections were numerically simulated.The results showed that the SBFs mainly appeared under high pressure systems,or in the edge parts of high-pressure systems where there were steady weather backgrounds.The SBFs were classified into two types as follows:The SBF Type I were located around the westward extending parts of subtropical highs over the sea;and the SBF Type Ⅱ were located under continental high-pressure systems entering the sea,in which their circulations usually had several more local systems and were accompanied by strong convective systems.The vertical cross-sections of the SBF events showed that the u-component of the east winds at low levels formed the frontal edges of the cold air masses from sea.This impacted the positions and intensities of the lifting motion of the SBF fronts.The secondary circulation of the SBF formed unstable environments.It was observed that when the SBF in coastal areas met the inland convective systems,it stimulated and enhanced the local convection.The data analyses of wind towers showed that the features of the time series of the SBF winds included sudden changes in wind directions and increases in wind speeds.The local systems' convective available potential energy (CAPE) showed that the meeting of the CAPE high value inland and SBF could potentially increase the local CAPE values.When a vapor convergence center was present,a local stimulating condition was built for the SBF acting on the convective systems.The numerical simulation showed that the horizontal distribution of the CAPE,and the release which met the SBF and strong convection inland.Meanwhile,the vertical profiles of the CAPE indicated the increase,release,and duration of the strong convection energy stimulated by the SBF.It was determined that the release action was fast,and the duration was approximately two hours.
keywords:Type Ⅰ and Type Ⅱ of sea breeze front(SBF)  stimulation of strong convection  convective available potential energy(CAPE)  numerical simulation of stimulation
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