【作者】 刘运成；

【导师】 王澄海；

【作者基本信息】 兰州大学 ， 气象学， 2006， 硕士

【摘要】 本文利用四川省广元市35年的暴雨雨量资料分析了以广元为代表的青藏高原东侧的四川盆地北部出现暴雨的一些气候规律;结合2005年7月15日至19目的高空地面实况资料和风云二号卫星云图资料对7月18日至19日出现在盆地北部的区域性大暴雨天气过程进行了天气学分析,应用湿Q矢量进行了动力诊断分析。从湿Q矢量散度场、锋生函数场与暴雨落区的关系入手,分析了暴雨不同阶段,高低层湿Q矢量散度场时空分布特征,探讨了其锋生作用与暴雨系统发生、发展的关系,揭示了造成这次暴雨天气过程的可能物理机制。结果表明:(1)湿Q矢量对暴雨中尺度系统的环流特征具有良好的诊断性,越接近强降水出现时间,诊断效果越好,其散度辐合区对应强降水区,最强降水出现在辐合中心附近的中心西北到零线梯度较大处,低层散度对暴雨落区的诊断要比高层好。(2)700hPa锋生中心可以对应12小时后的暴雨区,而当不稳定能量大量释放后,有锋消作用,大气趋于稳定层结,暴雨将逐渐减弱。(3)造成盆地北部此次大暴雨天气可能的物理机制是:a、在副高堵塞下的高空槽线和低层切变线是这次暴雨的主要影响系统。b、低层700hpa和850hpa偏南低空急流把孟湾和南海的暖湿空气不断地向盆地输送,使高位势不稳定能量不断增强,并使盆地北部处于急流左侧辐合区。c、川北发展生成的MCC是造成这次暴雨的直接系统。d、地面冷锋的南下,触发了暖湿空气中不稳定能量的释放,出现了暴雨。更多还原

【Abstract】 In this paper, based on the rainfall precipitation data oftorrential rain in Guangyuan city from 1971 to 2005, an investigation is conducted in some climatic characteristics of torrential rain in North Sichuan Basin on the east side of Qinghai-Xizang Plateau in recent 35 years. By using the FY-2 infrared imagery and the routine sounding and surface observation data on 15~19 July 2005, a synoptic analysis of the regional torrential rain process occurred in North Sichuan Basin on 18—19 July 2005 is made. Using the wet Q-vector, a dynamic diagnosis is made. Through examining the relations between the heavy rain area and the fields of divergence and frontogenetic function of the wet Q-vector, the temporal and spatial distribution characteristics of the divergence field during this heavy rain process are analyzed, and the relation between the generation and development of the rainstorm system and the frontogenetic function is probed into, and the probable physical mechanism producing this rainstorm process is revealed. The results are as follows: (1) The wet Q-vector has a good diagnostic property for the secondary circulation of the mesoscale systems of the heavy rain, especially near the heavy rain time. The convergence area of its divergence field can correspond to the heavy precipitation area, and the position of maximum rainfall is near the northwest of the convergence center, and the corresponding relation between the lower-level divergence of the wet Q-vector and the heavy rain area is better than that of the upper level divergence. (2) The center of frontogenesis can correspond to the torrential rain area of 12 hours in the future. After the instability energy is released largely, the air mass is inclined to the stability stratification and has the frontolysis, and the heavy rain decreases gradually. (3) The probable physicalmechanism of this event is: (a) The upper trough line and the lower shear line blocked by Northwest Pacific subtropical high are the main influencing systems of the torrential rain, (b) The southerly low-level jet streams on 700hPa and 850hPa transport the warm and moist air from the Bay of Bangle and the South China Sea to Sichuan Basin continuously, which enhances potential instability energy continually and locates North Sichuan Basin in the convergence area of the left side of the jet. (c) The mesoscale convective complexes(MCCs), which develop in North Sichuan Basin, are the direct influencing systems which cause this heavy rainfall, (d) The northerly surface cold front triggers the release of instability energy in the warm and moist air mass and the heavy rain occurs.更多还原