【作者】 滕跃； 王万瑞； 罗慧； 庞文保； 陈雷华；

【Author】 TENG Yue1 WANG Wan-rui2 Luo Hui2 PANG Wen-Bao1 CHEN Lei-hua1(1.Meteorological science and technology service center of Shaanxi Province,710015;2.Meteorological Bureau of Shaanxi Province,710015)

【机构】 陕西省气象影视宣传中心； 陕西省气象局；

【摘要】 本文利用陕西数值预报产品、常规探空、自动站资料、地面、高空常规资料及FY-2C卫星等资料,从暴雨产生的环流背景、动力条件、热力因素、水汽条件和物理量特征等几个方面入手,对2008年7月19日晚至22日强降水进行诊断分析表明,受大环流形势及高空西南涡不断加强东移影响,陕西中南部出现了区域性暴雨天气过程。这次区域性暴雨发生时具有强烈的抬升运动,强烈的抬升运动携带大量的水汽迅速上升,触发不稳定能量释放,形成大降水;暴雨是产生在前期大气对流不稳定区域里;暴雨区域基本分布在对流层中低层湿位涡的负值区内,低空急流为暴雨区输送大量的不稳定能量、热量及动量,为暴雨的产生提供了充足的能量条件和水汽来源;暴雨过程中低层辐合、高层辐散,高层辐散强于中低层辐合作用,这样的环流形势有利于加强低层辐合和对流上升运动,为暴雨的产生提供了动力因素;低层水汽主要来自孟加拉湾,水汽经过西南涡东侧的偏南风输送到陕西境内,系统与强降水中心有较好的对应关系;物理量场反映出暴雨区低层有充沛的水汽辐合,暴雨出现前期有较强能量聚集;湿度场与上升运动的有效耦合是暴雨发展和维持的动力机制。更多还原

【Abstract】 An intensified precipitation case lasting from 19th to 22nd July was discussed by using data from numerical predicting system,sounding,automatic weather station and FY2C.After analyzing the background circulation,aerodynamic condition,thermal properties,etc.,several property of this case was concluded:a strong lift carrying large amounts of water vapor triggered the releasing of unstable energy,which caused the formation of large precipitation;the precipitation area was very convective unstable,the low-level jet supported most water vapor;the divergence in the upper level was stronger than the convergence in the lower level,which was benefit for the sustaining of upward movement of air;the vapor was from Bay of Bengal,and was transported into Shannxi province by the south wind in the east edge of South-west Vortex;in conclusion,the couple between the circulation and the movement of water vapor caused the sudden heavy rain.更多还原