摘要
利用常规观测资料、地面自动站资料、雷达资料、卫星云图及NCEP 1°×1°再分析资料,对2015年6月20日和8月19日发生在林芝市的两次暴雨过程进行对比诊断分析。结果表明:"6.20"过程发生在副热带高压稳定少动的环流背景下,"8.19"过程发生在伊朗高压东伸与西太副高形成两高之间切变线的环流形势下;暴雨区低层水汽强烈输送和垂直运动强烈发展以及对流层中低层辐合、高层辐散的典型配置是两次过程共同的特点,"8.19"过程水汽输送较"6.20"更为通畅,配合低空急流,辐合更强,且"8.19"过程较历史个例而言,具有移动缓慢,系统深厚的特点,强降水落区同强垂直上升运动、低空强辐合及高空强辐散、水汽通量辐合中心相一致;"8.19"过程有明显的冷空气下传过程,存在强的高低空急流,且云顶温度更低,对流系统发展更高,云顶温度低于-60℃中心维持时间较长,强降水出现在云顶温度低值中心及其梯度大值区内。
Through the analysis of two torrential rains at June 20 and 19 August, 2015 , in Nyingchi. Our analyses are based on conventional observation data, ground automatic station data, radar wind profile, satellite images, and 1°× 1°reanaly-sis data of NCEP. These two torrential rains display different situation : the former occurs in subtropical stable sedentary circu-lation background and unstable energy increasing processes. The latter occurs in the circulation situation of a shear line which is formed between Iran high pressure and deputy high pressure, and unstable energy releasing processes. Both of the processes perform intensive moisture transportation in lowlevel rainfall areas, strong development of vertical movement, convergence in middle and lower troposphere, and divergence in high - level. Besides, the intensity of heavy rainfall as well as vertical drop area are consistent with strong vertical upward movement, strong convergence in low - level and strong divergence in high - lev-el ,and convergence center of moisture flux. However, the latter behaves obvious downstream processes of cold air, intensive high - and low - level jet, lower cloud top temperature, higher convective system development, the center of cloud - top tem-perature below - 60℃ and stays longer. And torrential rains appears in the low center of cloud - top temperature and its gradi-ent large value area.
出处
《高原山地气象研究》
2017年第2期8-15,共8页
Plateau and Mountain Meteorology Research
关键词
极端暴雨
环流
对流
云顶温度
extreme rainstorm, circulation, convection, cloud-top temperature