【摘要】 用实况降水、雷达反射率、欧洲中心(ECMWF)全球模式细网格及0. 5°×0. 5°分辨率ERA-Interim再分析等资料,对2016年15日发生在浙江省沿海地区的强降水过程进行分析和诊断,结果表明:该过程是由14号台风"莫兰蒂"的外围螺旋雨带产生的; 15日在浙江东部沿海地区有充沛的水汽,源源不断的水汽输送和明显的不稳定层结条件;在边界层辐合线、山脉地形、边界层急流头部三者共同作用下,该区域形成强烈的边界层辐合上升运动,触发了对流;对流层高层200 h Pa高空急流右后侧和气流发散区叠加,提供了强的高空水平辐散,有利于低层辐合上升的维持和发展,最终导致浙江沿海地区发生强降水。对比分析发现模式预报的边界层东南偏东急流及边界层辐合线均明显比实况弱,这可能是各大数值预报中心对这次过程的预报都明显偏小的主要原因,说明边界层东南偏东急流及边界层辐合线对于强降水具有重要作用。更多还原

【Abstract】 A severe local rainfall case occurred on September 15,2016 in the coastal region of Zhejiang province is analyzed based on a synthetic dataset including conventional observations,radar data,and ERA-Interim reanalysis data with horizontal resolution of 0. 5 × 0. 5 degrees. Results show that the heavy rainfall was directly produced by the outside spiral rainbands from typhoon Meranti. On September 15,2016 the sufficient moisture,vapor transportation and the unstable atmospheric stratification were evident in eastern coastal region. The combined effects of the boundary layer convergence line,topography and the front part of boundary layer jet induced the strong boundary convergence and updraft flow formed and triggered the convection. At upper level of troposphere( 200 h Pa),the overlap of the right back side of upper-level jet and divergence zone provided intense divergence,which is advantage to the development and maintenance of lower-level convergent updraft,ultimately led to occurrence of the heavy rainfall. Comparison of the intensities of boundary southeasterly jet and convergence line between the model forecasts and observations uncovered that the model forecasts is weaker than the observations,which probably is the primary factor that results in the underestimation of the heavy rainfall intensity in each global numerical weather prediction center. It shows that the boundary southeasterly jet and convergence line have played an important role in this heavy rainfall process.更多还原