一次飑线过程的数值模拟及诊断分析

Numerical Simulation and Diagnostic Analysis of a Squall Line Process

利用常规资料、气象卫星、多普勒天气雷达、NCEP/NCAR再分析资料以及中尺度数值模式WRF,对2013年8月10日凌晨发生在青岛近海上空一次飑线大风过程进行了数值模拟和诊断分析。结果表明:此次飑线过程与低空急流的水汽输送、高空急流入口区右侧的强辐散抽吸以及850 h Pa切变线的触发等因素共同影响形成。分析飑线的垂直结构,发现高空存在强烈辐散,低空存在强烈辐合,对流层中高层较干的下沉气流,是导致海面强阵风形成的主要原因。对假相当位温、k指数等物理量进行诊断分析发现,出现海难事故海区强对流发生前大气层结不稳定。利用WRF模式成功地模拟了此次飑线过程,表明可利用区域中尺度数值预报模式分析强对流天气系统的结构和时空变化特征。

Using regular observation data,weather satellites data,doppler radar data, NCEP/NCAR reanalysis data and the mesoscale model WRF to make the numerical simulation and diagnostic analysis on the strong squall line process ,which occurred in Qingdao＇s near sea area ,in the early morning of August 10th ,2013. The results showed that low-level jet with water vapor transport ,right side of entrance region of upper-level jet stream with strong suction ,and trigger of 850 hPa shear line ,affect the formation of the squall line process.Vertical structure analysis of the squall line found that there was a strong divergence in upper-level, a strong convergence in low-level, descending dry current from the middle and upper of troposphere, which were the main cause of the formation of strong wind on the sea-level.The diagnostic analysis of pseudo-equivalent potential temperature and k-index found that there was a instability before severe convective weather occurred.Using the WRF model the process of the squall line process successfully simulated,which indicated that it could take advantage of regional mesoscale numerical weather prediction model to analysis the structure, the spatial and temporal distribution of severe convective weather systems.