地形和高层环境对爆发气旋影响的数值研究

A NUMERICAL STUDY OF THE EFFECTS OF THE TERRAIN AND THE UPPER LEVEL ENVIRONMENT ON THE EXPOLOSIVE CYCLONE

利用ＰＳＵ／ＮＣＡＲ中尺度模式对地形和高层环境在１９８３年４月２５日－２７日一次气旋爆性发展中的作用，进行数值试验．在控制试验（包括全物理过程）中，模拟气旋路径和气旋迅速发展同实际观测的类似．诊断分析结果表明高空两支急流、凝结潜热释放及积云混合对这次气旋迅速发展有显著贡献．在地形试验中，发现由太行山、燕山由脉、大兴安岭诱生的地形槽对气旋发展也有明显作用．如取均匀高度作为１００—３００ｈｐａ初始等压面高度场，并积分２４小时，则中低层短波槽消失斜压性减弱，次级环流受到抑制，地面只出现一个浅薄的低压，但低压移动路径则不受影响．

In this paper, the effects of the terrain and the upper level environment on the explosive cyclone have been studied by using Psu / NCAR meso-Scale model MM4. In a control experiment containing full physical processes, the path and its rapid development of simulated cyclone agree well with observed cyclone. Diagnostic analysis of the simulated output shows that the two upper level Jets, latent heat released and Cumulus mixing contribute obviously to the developmet of the explosive Cyclone. In the experiment of the effect of the terrain, it is found that the trough induced by the Taihang Mouuntains, the Yan Mountains and the Greater Xing an Mountains also has distinct influence on the explosive evolution of the cyclone. When the homogeneous heights of 100, 200 and 300hpa were used as initial fields and integrated 24h, the short wave trough in middle-low layers of troposphere disappeared, the baroclinicity weakened, the secondary circulation reduced and only a shallow depression at the surface occurred in 24h forecast fields, while the path of the depression was unaffected in the experiment.