摘要
近6年河北夏季降水统计与诊断分析显示,太行山东侧的华北平原中南部是夏季暴雨灾害频发地区,雨带多沿太行山脉经向分布,过程雨量往往达到700 mm以上。重点研究夏季下山锋面黄河气旋和暴雨,该类系统占统计样本73次暴雨日数的20%。对2016年典型锋面黄河气旋大暴雨的分析显示,太行山脉的经向分布与气旋北部的向山气流和气旋西部的南下气流配合,引导形成沿山脉走向的深厚狭长冷温度槽,增强锋面气旋中的温度梯度,加强气旋斜压性和旋转风强度,导致气旋加强,东移速度减慢。通过气旋急流的卷夹与山脉阻挡的配合造成深厚的充沛水汽环境,阻碍水汽通量和低层水汽主体西进;在山脉东侧形成高能舌对流不稳定;触发含充沛水汽团的强烈抬升,形成3处垂直运动关键区,制约暴雨落区。太行山脉坡度对暴雨影响机制的数值试验显示:坡下暴雨区与山脉平行,且经向山脉走向可造成更大范围强降水,并易造成局地经历气旋暖锋与冷锋二次锋面降水,致使暴雨持续时间拉长。山脉坡度与山脉阻挡抬升强度成正比,并形成下干上湿对流不稳定与锋面上暖下冷热力不稳定叠加,不稳定性更强。山脉坡度与气旋下山减压增强及维持时间成正比,与向华北平原下滑远近成反比,即影响气旋东移路径与速度。
The statistical and diagnostic analysis of precipitation in Hebei Province in the past six years shows that the mid-south of the North China Plain on the east side of the Taihang Mountains is an area of frequent rainstorm disasters in summer. The rain belt is mostly distributed along the Taihang Mountains,and therainfall is often over 700 mm. Focus was on the summer downhill frontal Yellow River cyclone,which accounted for 20% of the 73 storm days in the statistical samples. The analysis of the typical frontal cyclone heavy rain in2016 shows that the meridional distribution of the Taihang Mountains cooperates with the climbing mountain jet in the north of the cyclone and the southward flow in the west of the cyclone,leading to the formation of a deep narrow cold temperature trough along the mountain orientation. It enhances the temperature gradient in the frontal cyclone,enhances the baroclinicity of the cyclone and the intensity of the rotating wind,resulting in augmentation of the cyclone and slowing of the eastward movement. Through the cooperation of the entanglement of the cyclone jet and the mountain block,a deep and abundant water vapor environment is formed,and the moving westward of water vapor flux and the low-level water vapor main body are hindered;The high-energy tongue convection instability on the eastern side of the mountain range is formed,a strong uplift with abundant water vapor masses is triggered,and three critical areas of vertical motion occurred,which restricts the rainstorm locations. Numerical experiments on the mechanism of the influence of the slope of the Taihang Mountains on heavy rain show that the downhill rainstorm area is parallel to the mountain range,and the meridional mountain range can cause a greater range of heavy precipitation. It is also easy to cause double frontal precipitation locally by a same cyclonic warm front and cold front,resulting in a long duration of heavy rain. The slope of the mountain is proportional to the intensity of the mountain block and forms the wet convection instability with the dry at lower and wet at upper overlapping on a thermal instability of the front zone with cold at lower and warm at upper,such as the total instability is stronger. The slope of the mountain is proportional to the increase and maintenance time of the cyclone decompression during downhill. It is inversely proportional to the decline to the North China Plain,which affects the path and speed of the cyclone eastward movement.
作者
王坚红
张萌
任淑媛
王兴
苗春生
Wang Jianhong;Zhang Meng;Ren Shuyuan;Wang Xing;Miao Chunsheng(Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China;Jilin Meteorological Service Center,Changchun 130062, China;College of Atmospheric Science, Nanjing University of Information Science & Technology,Nanjing 210044, China;School of Marine Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China;Lanzhou Meteorological Observatory, Lanzhou 730020, China;Nanjing Xinda Institute of Meteorological Science & Technology, Nanjing 210044, China)
出处
《地球科学进展》
CAS
CSCD
北大核心
2019年第7期717-730,共14页
Advances in Earth Science
基金
国家自然科学基金面上项目“海洋中尺度涡旋动力结构与维持机制研究”(编号：41276033)
国家自然科学基金青年科学基金项目“下击暴流智能识别和预报预警的方法研究”(编号：41805033)资助~~
关键词
太行山脉东侧坡度
华北南部暴雨
下山锋面黄河气旋
山脉坡度影响机制
数值模拟试验
East side slop of Taihang Mountains
Southern rainstorm of North China
Downhill Yellow River Cyclone with fronts
Impacting mechanism of terrain slope
Numerical simulation experiments
