一次梅雨锋结构及锋区强度对锋面结构影响的数值模拟  

Structure of Meiyu Front and Its Sensitivity Experiment of Relationship between Front and Vortex Disturbance

作　　者：陈丽芳[1] 周春雨[1] 郦敏杰 查贲[1] 

机构地区：[1]杭州市气象局,浙江杭州310052

出　　处：《高原气象》2009年第4期924-934,共11页Plateau Meteorology

基　　金：浙江省气象科技开放研究专项(kf2008006)资助

摘　　要：利用中尺度模式MM5对1999年6月下旬发生在长江中下游地区的一次锋上西南低涡发展的梅雨锋暴雨过程进行了研究。通过敏感性试验,探讨了低涡对锋强、锋生的敏感性,锋生、锋消与低涡发展演变的时间空间上的联系等问题。结果表明,低涡对中层锋面强度的变化敏感,中层锋强发生改变会导致整层涡度发生同位相的变化。中层系统对梅雨锋气旋的发展起主要作用,中层锋面对低涡发展的影响比边界层锋更关键。中层锋面强度改变会激发出中低层的垂直次级环流,低层的辐合上升运动发生改变,最终影响到低涡强度的发展。敏感性试验证明,锋面强度变化对低涡发展造成的影响有超前性,中层锋面先发生变化,6 h左右以后低涡强度发生改变。锋区强度和低涡强度发生变化的地理位置基本在同一经度上,锋强变化的位置在涡强变化位置的北面。Using the meso-seale model MM5 the relationship between the development of south-west vortex and Meiyu front in the middle and lower reaches of Yangtze River in June 1999 are studied. The intensity transform of front or not, and space-time relationship between frontogenesis, frontolysis and vortex evolution were studied through sensitivity experiments. The results show that the low vortex was sensitive to intensity transform of middle level front. If intensity of middle level front was changed, vortex vorticity at every level would change in phase. Middle level system had great effect on development of cyclone along Meiyu front. As for vortex evolution, middle level front was more important than boundary layer front. Perpendicular sub-circulation would develop if intensity of middle level front changed. The development of sub-circulation lead to divergence changing in low level, and finally it would effect to the intensity of vortex. Only increasing the intensity of boundary layer front could not result in low vortex developing. If we changed the intensity of middle level front in the initial time, the intensity of middle level front would change out of phase after integrating some hours. Sensitive experiments proved that the development of middle level front would influence the development of vortex after 6 hours or so. The development of south-west vortex and Meiyu front was not at the same time. The frontogensisi appeared about 6 hours earlier than the development of vortex. The place that intensity of front and low vortex changed was almost at the same longitude. The place that front intensity changed was at the north of that vortex intensity changed. So there was a good relationship between Meiyu front and low vortex along it.

关 键 词：敏感性试验 相对湿度 中层锋 边界层锋 

分 类 号：P445[天文地球—大气科学及气象学]