初值水汽场对华南春季一次强飑线触发和维持影响的数值试验

NUMERICAL SIMULATION OF THE INFLUENCE OF INITIAL WATER VAPOR ON THE TRIGGER AND MAINTENANCE OF A SEVER SPRING SQUALL LINE IN SOUTH CHINA

在对观测资料分析的基础上,采用WRF模式探讨初始场水汽分布对华南2014年3月30—31日产生雷暴大风、强降水的飑线过程触发和维持的影响。研究基于ERA-interim和NCEP-FNL再分析资料在华南地区水汽分布的差异性,设计了四组将两类资料水汽按比例融合作为初始场的数值试验,水汽场从NCEP-FNL越靠近ERA-interim水汽,模拟的飑线演变越趋近实况,试验结果表明更准确的水汽初始场有利于提高飑线等强对流系统的预报准确率。在对流初生阶段,区域内水汽含量增多,最大有效位能增大,对流越容易触发;对流发展中后期,充沛的水汽有利于飑线组织形态和强度的维持。

Based on analysis of observational data,the influence of initial water vapor distribution on the triggering and maintenance of a squall line process,which occurred with strong wind and heavy rainfall over the south of China on March 30-31,2014,is investigated by the WRF model.According to the differences between ERA-Interim and NCEP-FNL reanalysis in the south of China,four tests of numerical simulations with different initial water vapor fields were designed by merging the two reanalysis datasets in proportion.Contrast tests confirmed that when initial water vapor evolves from NCEP-FNL to ERA-interim,the simulation results tend to approach real situation more closely.Therefore,it is advantageous to improve the predictability of squall line and other strong convective systems by constructing more accurate initial water vapor field.In the initial stage of convection,the more the water vapor content in the region accompanied by greater maximum available potential energy,the easier the convection is triggered.In the later convection development,abundant water vapor is conducive to the maintenance of organization and strength of squall line.