摘要
本文利用一套具有中尺度分辨率的观测资料,对发生在1983年6月下旬的一次长江流域梅雨暴雨过程进行了诊断研究,并比较了该过程的对流降水活跃期和非活跃期的中尺度环境场特征。结果表明,两个时期的动量场存在明显差异,而水热场差异不大,Q_1和Q_2以及涡度收支也存在明显差异。在降水活跃期(暴雨集中期),积云对流对能量和涡度的垂直输送有着重要作用;在水热收支中,起主要作用的是垂直输送项,潜热加热基本上为抬升冷却所平衡,水汽的垂直输送是积云对流的主要水汽源;在涡度收支中,低层散度项和扭转项制造正涡度,并通过积云对流向上输送,无论在低层或高层积累的正涡度都被平流非线性过程所耗损。
A diagnostic study with a dataset of mesoscale resolution for the heavy rain process occurred over a region of Yangtze River during the third decadel days of June in the 1983 Meiyu season is presented in this paper. Comparisons are made of the mesoscale environment characteristics in a disturbed and an undisturbed period. The results showed that significant differences were found in the momentum field, Q1 and Q2, as well as the vorticity budget in the two periods. However not much difference was observed in the heat and moisture fields. In the disturbed period with heavy rain, the feedback effects of cumulus convection are important. Q1 and Q2 are mostly contributed by the vertical advection terms. The condensation heating is almost balanced by the cooling effect of ascending motion. The vertical transport of moisture is the major source of Water vapor for the cumulus convection. As to the vorticity budget, positive vorticity is produced by the convergence and twisting terms at low levels and is transported upward by the cumulus convection. In both upper and lower layers, accumulated positive vorticity is dissipated by nonlinear process of advection.
出处
《热带气象》
CSCD
1991年第1期16-25,共10页
