台风角动量平衡的诊断分析

本文根据文献6],应用FGGEb资料,计算了7908号台风四个同心区域的质量收支和绝对角动量收支,得到以下结果:台风的演变过程可以由其旋转轴确定的绝对角动量来表征。在台风发展最盛时,对流层中层角动量达到最大;台风绝对角动量主要来源于水平侧边界输送。对于侧边界角动量输送,计算结果表明:在台风形成以前,涡动方式(非对称气流)输送是主要的;在台风形成初期,平均和涡动两种方式的输送具有同等重要性;在台风发展强盛及其减弱期,以平均输送为主。比较各强迫函数的作用,凝结潜热释放则是影响角动量垂直输送的重要因子。根据角动量平衡,发现次网格尺度效应显著,说明系统内部角动量再分配机制,除了角动量向上输送以外,积云对流活动可能是另一重要的方式。

A DIAGNOSTIC ANALYSIS ON THE ANGULAR MOMENTUM BALANCE OF TYPHOON Hope

On the basis of the document(6), the mass budget and absolute angular momentum budget in four concentric areas of the typhoon 7908 are calculated with the application of the FGGE3B data. It follows that the process which the typhoon evolves may be characterized by the angular momentum about its axis during the most prosperous development of the typhoon the angular momentum in middle troposphere reachs maximum and that absolute angular momentum of the typhoon mainly comes from the lateral transportation. As concerning lateral transportation, the results also show that the eddy transport (due to asymmetic circulation)is important before the typhoon genesis; the average and the eddy transport both have the equivalent impor - tance in the early stage of the typhoon; the average transport is more important during the most prosperous development and the decay of the typhoon By a compa rison between the forcing functions, it is found that the condensation heating is more important factor affecting the vertical transportation of angular momentum. On the basis of the angular momentum balance ,it is found that the effect of subgrid scale is marked, which shows that the action of the cummlus convection may be another important manner to the redistribution mechanism of momentum in the system besides vertical transportation.