A study of meso-scale vortex-like convective clouds observed over the seas around Japan

日本周边海域观测到的中尺度涡旋对流云研究

基本信息

批准号：
60460048
负责人：
ASAI Tomio
金额：
$ 4.35万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1987
项目状态：
已结题

项目摘要

Vortical convective cloud patterns in meso-scale ranging from[10km to [100km gave been frequently found over the seas around Japan, since observation by the geostationary meteorological satellite "Himawari" was available in 1987. The objectives of the present study is to elucidate seasonal and geographical distributions of meso-scale vortical convective clouds and mechanism of their development besed on an observational study and laboratory and numercal experiments.The results obtained so far are summarized as follows.(1) Statistical analyses of satellite cloud pictures show two preferred areas in the Sea of Japan in winter where meso-scale vortical clouds are most frequently observed : 1) east of Korea peninsula and 2) west of Hokkaido Island. These vortical clouds gaving cyclonic vorticity and life-time of several hours move to southeast in a speed of 10ms^<-1> and some of them vanish just after landing to coastal regions of Japan.(2)Band clouds accompanying horizontal convergence and cyclonic shear are observed and the vortical clouds are often formed in the bands : one is a convergence zone between northerly wind from Siberia and westerly wind from Korea peninsula and the other is a convergence zone between northwesterly from Siberia and northeasterly from Hokkaido. This suggests that meso-scale vortical disturbances may be formed favorably in the convergence zones.(3) A well-developed trough or a cold vortex in the upper troposphere and a northwesterly monsoon in the lower tropposphere provides a deep potentially unstable layer over the Sea of Japan. This is favorable for development of meso-scale vortical convective clouds in association with topographically induced convergence and shear zones.

自 1987 年静止气象卫星“向日葵”观测以来，日本周边海域经常发现中尺度范围从 10 公里到 100 公里的涡旋对流云模式。本研究的目的是阐明季节性基于观测研究、室内和数值实验，研究了中尺度涡旋对流云的地理分布及其发展机制。 (1)卫星云图统计分析表明,日本海冬季中尺度涡旋云最常出现的两个区域是:1)朝鲜半岛东部和2)北海道岛西部。这些具有气旋性涡度和数小时寿命的涡旋云以10ms^<-1>的速度向东南方向移动，其中一些在登陆日本沿海地区后就消失了。 (2)伴随水平辐合和气旋的带状云观测到切变，涡旋云常形成于带状区域：一是西伯利亚偏北风与朝鲜半岛西风的辐合带，二是西北风的辐合带。来自西伯利亚和北海道东北。这表明中尺度涡旋扰动可能在辐合区有利地形成。(3)对流层上层发育良好的低压槽或冷涡以及对流层下层的西北季风在海上提供了一个深层的潜在不稳定层。日本的。这有利于与地形引起的辐合和剪切带相关的中尺度涡旋对流云的发展。