涡群中双涡合并的数值研究及一次江淮梅雨中的涡旋合并过程分析

【作者】 雷正翠；

【导师】 马镜娴；

【作者基本信息】 南京信息工程大学 ， 气象学， 2005， 硕士

【摘要】 台风和江淮梅雨暴雨是我国非常典型的两类气象灾害。目前对台风路径的预报已取得了很大进展,对于正常台风的预报是比较准确的,但是对于突然加强的台风的预报还存在很大问题,我国和国外的许多专家学者对此作了大量有意义的工作,取得了许多积极的成果。然而台风内部结构以及外部环境因素等方面的复杂性,至今还未能完全认识其发生、发展的原因和机制,还需对此进行更深入的研究。目前江淮梅雨暴雨也得到了广大气象工作者的广泛关注,在这方面也做了大量卓有成效的工作,但是由于梅雨天气系统自身的复杂性,我们也未能清楚地了解其规律,还有大量的工作值得我们去做。 由于涡旋合并与台风、梅雨都有着密切的关系,本文首先在涡旋自组织动力学的框架内,利用f平面正压涡度方程模式,数值地研究了涡群中双涡相互作用的问题,对比了弱环境流与涡群环境流两类条件下双涡作用的异同。指出:弱环境流条件下双涡合并的过程,在涡群环境条件下不再存在;同时,涡群环境流的引进可使涡强度显著增强。 其次由于云团合并与涡旋合并两者相当,因此云团合并或涡旋合并过程,可能在强暴雨中心的形成中起着重要作用。本文利用2003年7月每日4个时次的1°×1°NCEP风场、湿度场、高度场等再分析资料,对2003年7月8日至9日江淮流域暴雨过程中的涡旋合并过程进行了分析,结果表明:(1)江淮流域上空的中尺度涡旋合并与此次暴雨过程密切相关。涡旋合并使得低层辐合、高层辐散加强,使得垂直速度、水汽输送、湿螺旋度加强,从而导致暴雨增幅。(2)低层辐合、高层辐散的高低空配置有利于强上升运动的维持,强上升气流所携带的水汽和能量有利于对流云团的发生发展,有利于暴雨的维持。(3)来自孟加拉湾和南海的暖湿气流为江淮流域提供了充足的水汽。更多还原

【Abstract】 Typhoon and storm rainfall is two types of China’s representative meteorological disasters. Presently many achievements have been gained in the track of typhoon and the forecast of typhoon. It is accurate to forecast normal typhoon, but there are many difficulties in the forecast of enhanced typhoon suddenly. Currently many meaningful research on typhoon have been done by domestic and foreign meteorologists and a lot of meaningful results have been achieved. However, due to the complexity of the inner structure of typhoon and the outer surroundings, the cause and the mechanism of typhoon enhanced suddenly have not been known completely today and the further research on the law of the evolutive process of typhoon is needed. At present lots of meteorologists pay attention to the reseaches about Meiyu occurred in Jianghuai and have made large qualities of successful pursuits. Because of the complicacy itself, we cannot understand distinctly the rule of it. It is worthy of doing substantive investigations.Owing to vortex merger has consanguineous association with typhoon and rainfall, in the frame of the vortex self-organization dynamics the question of the interaction between double vortices is investigated by using numerical model and the differences and homogeneities of double vortices interaction under the two types of conditions involving weak outer fields and swarms of vortices as ambient flow is contrasted. It is shown that the merger process of the double vortices in the case of weak ambient fields doesn’t exist under the circumstances of groups of vortices, in the meanwhile, the introduction of swarms of vortices can make vortex intensify.Because the merging of cloud group is consistent with that of vortices, the merging of cloud group or vortices may be important in the cause of the center of the heavy rainfall. A heavy rainfall occurred in Jianghuai during 8-9July 2003 .The above-mentioned case has been analyzed using the reanalyzed data 4 times a day from NCEP including wind, humidity and height fields. The results show that the heavy rainfall was mainly associated with the mesoscale vortices merger. It was noticed that relative vorticity, divergence, vertical velocity, the delivering of the moisture, and moist spiral divergence were strengthened. It was shown that the Bengal Bay and the South China Sea may be the important moisture source place. It was emphasized that lower levels convergence and higher levels divergence was important of the maintenance of the heavy ascending motion and the convective systems were benefited from the heavy ascending air.更多还原