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Structure and Dynamics of Convective Clouds that Cause Wind Hazards

造成风灾的对流云的结构和动力学

基本信息

批准号：
09440166
负责人：
NIINO Hiroshi
金额：
$ 6.46万
依托单位：
Ocean Research Institute, The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 2000
项目状态：
已结题

项目摘要

The structure and dynamics of convective clouds that produce tornadoes and downbursts in relatively humid regions like Japan was studied by means of a numerical simulation and by analyzing observational data derived from Doppler radars. In order to clarify the characteristics of the environment for tornado-producing convective clouds, a tornado database between 1961 and 2000 in Japan was compiled, and so-called bulk parameters that characterize meso-scale environment was examined based on the upper air sounding data of Japan Meteorological Agency between 1988 and 1999.1. Tornado-producing stormsOn the evening of 19 September 1990, at least three tornadoes occurred in Kanto District in association with Typhoon 9019. Our Doppler observation revealed that nine mini-supercells occurred over the District and their detailed structure was clarified. A numerical simulation in which the upper air sounding at Tateno at 2100JST was used as a horizontally uniform environment reproduced the observe … More d characteristics of the mini-supercell surprisingly well. The simulated storm exhibited a generation change every an hour. The vertical vorticity of the mesocyclone was found to be produced principally by tilting the horizontal vorticity in the environmental wind. Another Doppler radar observation of a mini-supercell that spawned two tornadoes in Chiba prefecture on 5 July 1996 detected clearly its generation change.2. Downburst-producing stormsA storm that caused damage-producing downbursts in Misato town in Saitama prefecture on 8 September 1994 was analyzed by using observational data. A numerical simulation in which the upper air soundings at Maebashi and Tateno at 1500JST was used as a horizontally homogeneous environment reproduced the observed characteristics of the storm well. The downburst was found to be initiated by the loading of graupel and hail at the upper level, and then intensified principally by the melting of graupel and hail near the OC level and secondly by evaporation of rain drops. Less

通过数值模拟和分析多普勒雷达的观测数据，研究了在日本等相对潮湿地区产生龙卷风和降暴的对流云的结构和动力学。为了阐明产生龙卷风的对流云的环境特征，利用日本气象厅1988 ~ 1999年的高空探测资料，编制了日本1961 ~ 2000年的龙卷风数据库，并对表征中尺度环境的所谓体参数进行了研究。产生龙卷风的风暴1990年9月19日晚上，关东地区至少出现了三个与台风9019有关的龙卷风。我们的多普勒观测显示，该地区上空出现了9个微型超级单体，它们的详细结构得到了澄清。以2100JST时馆野高空探测为水平均匀环境的数值模拟，较好地再现了观测到的迷你超级单体的更多特征。模拟的风暴显示出每小时发生一次世代变化。发现中气旋的垂直涡度主要是由环境风中的水平涡度倾斜产生的。1996年7月5日在千叶县产生两个龙卷风的一个小型超级单体的多普勒雷达观测清楚地发现了它的生成变化。利用观测资料分析了1994年9月8日在埼玉县Misato镇造成破坏的一场风暴。以1500JST前桥和馆野的高空测深作为水平均匀环境的数值模拟较好地再现了此次风暴的观测特征。该次降暴主要由上层的霰和冰雹荷载引起，然后主要由OC附近的霰和冰雹的融化和雨滴的蒸发加强。少