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气象:2014,40(1):18-27
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一次华南—江南持续暴雨的大尺度水汽场和中尺度特大暴雨模拟诊断分析
(1.中国气象局武汉暴雨研究所,暴雨监测预警湖北省重点实验室,武汉 430074;2.中国气象局乌鲁木齐沙漠气象研究所,乌鲁木齐 830002;3.湖北省气象信息与技术保障中心,武汉 430074)
Diagnostic Analyses of Large Scale Moisture and Mesoscale Severe Rainstorm Simulation of One Continuous Heavy Rain Event in South China
(1.Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research, Institute of Heavy Rain, CMA, Wuhan 430074;2.Institute of Desert and Meteorology, CMA, Urumqi 830002;3.Meteorological Information and Technology Support Center of Hubei Province, Wuhan 430074)
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投稿时间:2012-12-13    修订日期:2013-03-01
中文摘要: 按天气学方法,对2010年6月华南—江南持续暴雨作大尺度水汽场诊断分析,同时用三重嵌套WRF中尺度模式,模拟6月19—20日“高空槽—西南涡—切变线—低空急流”系统造成的江南特大暴雨过程,并且对模拟中尺度暴雨雨带和雨团作高时空分辨率诊断分析。诊断物理量包括:可降水量、对流可降水量、水汽及云水、云冰通量和通量散度、水汽权重平均风速、凝结函数降水率等。模拟与诊断分析表明,华南—江南持续性暴雨大尺度水汽场特征是,因东亚“中高纬度正距平—中低纬度负距平—副高偏强偏西—季风槽异常活动”,造成孟加拉湾和南海上空的大尺度水汽进入大陆;中尺度特大暴雨发生在上游区有暖湿急流、并处于风场辐合的“水汽+云水+云冰”(总水物质)饱和高值区;因凝结函数降水率和总水物质通量散度降水率均为风场(散度场)中垂直运动产物,模拟的凝结函数降水率随模式时空分辨率提高而逐渐逼近于模式的显式降水物理过程,当模式分辨率达到4 km,可模拟出“西南涡—切变线”系统中,有凝结函数降水率为1~3 mm·min-1的中尺度雨团生消;且模式大气中的云水、云冰碰幷增长降水率,可用其通量散度描述,并且应与凝结函数降水率相叠加。从而表明,模拟中尺度雨带和雨团发生、发展的天气学动力因素,只能是天气系统风场,即是模式的高时空分辨率散度场决定模式大气垂直运动,进而决定凝结函数降水率和总水物质通量散度降水率,它们一起构成了模式显式降水(率)
Abstract:According to diagnostic precipitation methods of calculating precipitable water, pseudo convection precipitable water, flux and flux divergence of moisture, cloud liquid water and cloud ice crystal, moisture weighted mean wind and condensation function precipitation rate, the continuous torrential rain that occurred over South China in June 2010 was diagnosed for its large scale moisture situation. Meanwhile, under the synoptic system of “upper trough-southwest vortex (SW vortex)-shear line-low level jet”, the extremely severe rainfall seen in Jiangxi, Fujian and Hunan in 19-20 June 2010 was simulated by a three nested, WRF model. The simulation and diagnostic analysis show that the large scale moisture field of the heavy rains in South China is characterized by “positive anomalous in the middle high latitudes-negative anomalous in the middle low latitudes-the subtropical ridge being positive anomaly towards west-anomalous activities of the monsoon trough” in East Asia, which causes the large scale vapor over the Bay of Bengal and the South China Sea to move into the Mainland of China. Many mesoscale rainstorms develop in high value areas of saturated water vapor, cloud water and cloud ice, where wind convergence and ascent motions take place and there are warm humid jet streams in its upstream. Both precipitation rates of condensation function and flux divergence of total water are products of the wind divergence initiating vertical motions, and the precipitation rate of condensation function gradually approaches approximation reasonable for explicit precipitation physical process in model atmosphere along with the improvement of spatial and temporal resolutions. When the model resolution reaches 4 km, rainfalls with the condensation function precipitation rate being 1-3 mm·min-1 can be simulated in the system of “SW vortex-shear line”, and the precipitation rate of collection growth of liquid and/or ice droplets in super saturated clouds can be described by their flux divergences and should be added to the precipitation rate of condensation function. Therefore, synoptic dynamic factors for the mesoscale rainfalls to occcur and develop in the model atmosphere is only the wind divergence field in weather system, for the vertical motions are determined by the divergence field with high spatial and temporal resolution in model atmosphere, so are all of the precipitation rates.
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基金项目:国家自然科学基金项目(41275106)和公益性行业(气象)科研专项(GYHY201106003)共同资助
引用文本:
辜旭赞,于晓晶,唐永兰,陈郁琴,2014.一次华南—江南持续暴雨的大尺度水汽场和中尺度特大暴雨模拟诊断分析[J].气象,40(1):18-27.
GU Xuzan,YU Xiaojing,TANG Yonglan,CHEN Yuqin,2014.Diagnostic Analyses of Large Scale Moisture and Mesoscale Severe Rainstorm Simulation of One Continuous Heavy Rain Event in South China[J].Meteor Mon,40(1):18-27.