梅雨云带上一个中—β尺度雨团的细分析

A FINE DIAGNOSE OF THE RAIN CLUSTER IN MEI - YU PERIOD

在华东中尺度试验期间,捕获到一个发生在固始地区的雨团,我们取水平格距为20km,垂直分为十一层,用“倒平方”公式对该雨团地区的气象资料进行诊断分析。发现在固始雨团发展、强盛期,对流层中层都存在中—β尺度的辐合系统。在雨团发展期该地区对流层有一个正环流;强盛期对流层中层以上的强盛上升运动导致降水,边界层中出现下沉运动;在雨团消亡期,整个对流层为上升运动,但强度大为减弱。此外还发现在雨团发展期,对流层中层出现弱的暖心结构;到强盛期,暖中心抬高到对流层顶附近。且其强度大为增强;而到消亡期,暖心结构趋于消失。

A rain cluster was detected in a mesoscale experiment in East China. The formula of inverse square is used here to diagnose information concerning the domain with 20 km interval horizontal grids and 11 vertical levels. During its developing and mature phases, a meso - β scale convergence system is found throughout mid-troposphere. In the developing phase, there is a positive cell in the troposphere. Strong updrafts in middle troposphere and above in the mature phase cause precipitation while downdrfats occur in the boundary layer. The decay phase is marked with much weaker ascending flow for the whole troposphere. Besides, the weak warm core in mid- troposphere rises to tropopause where it has intensified much, tending to dissipate in the decay phase.