物理量配置对浙江梅汛期暴雨落区影响的个例分析

Influence of Physical Features on Heavy Rain Region of Meiyu Seasons in Zhejiang

利用NCEP每日4次再分析资料,计算预报业务中常用的比湿、散度、兹se、A指数等物理量,对2011年梅汛期末场暴雨进行诊断分析。结果表明:在此次降水过程,暴雨落区与850 hPa切变位置对应较好,主要集中在西南急流的左前方,850 hPa辐合条件好的地区;暴雨带与低层水汽通量辐合区走向基本一致,暴雨带基本都在辐合带内,但其暴雨中心与辐合中心位置有时并不都一致;暴雨落区对应500、700、850 hPa高湿区(>90%区域)重叠区中低层风场辐合较好的区域较好;暴雨带处(850 hPa兹se锋区南侧边缘,但是兹se锋区梯度的变化与暴雨强度、范围变化对应并不一致;暴雨带处AI指数高值带内偏北侧一端,A指数增大,暴雨强度也增大,在暴雨预报中有指示意义。

Based on regional intensive precipitation data from weather statio as well as the NCEP reanalysis data,Physical quantity of specific humidity,divergence,θse and AI index is calculated,and the last heavy rain of Meiyu period on 2011 is analyzed.The result is that： area of the heavy rain is in accord with the shear line of 850hPa,and it focus on left front of westerly jet and convergence area of 850hPa;the heavy rain belt is in accord with convergence area of moisture flux of low layer,but the center of the heavy rain is not in accord with the center of convergence area of moisture flux some time;area of the heavy rain is in accord with overlay area of higt humidity area（rh90%） of 500,700 and 850hPa.the heavy rain belt is located south side of θse frontal zone of 850hPa,but the change of gradient of θse frontal zone is not in accord with the strength and range of the heavy rain.the heavy rain is located north side of the hight value zone of AI index,）and the strength of the storm rainfall is in conjunction with the strength of AI index.