Unusual Weather due to Irregular Activity of Polar Airmass and Associated Heavy Rainfall.

由于极地气团的不规则活动和相关的强降雨而导致异常天气。

基本信息

批准号：
03452061
负责人：
ASAI Tomio
金额：
$ 3.01万
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：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

The polar airmass dominates the weather in Japan which is located in the east of the Asian Continent. Baiu and Akisame fronts which form between the polar airmass and the tropical airmass are related to an activity of the polar airmass. An irregular behavior of the polar airmass sometimes causes unusual weather in Japan. Objectives of this research are the unusual weather due to the irregular activity of the polar airmass and the associated heavy rainfall.The NMC grid point data were analyzed by means of a statistic method to investigate the activity of polar airmass. High correlations were found in 500hPa height field during summer season in the southern hemisphere and during winter season in the northern hemisphere. A height anomaly in the southern hemisphere was relatively uniform in the zonal direction in comparison with that in the northern hemisphere.Behavior of the polar airmass was simulated in a laboratory experiment. While a rotating apparatus was axisymmetric, the axisymmetric flow was not stable and a non-axisymmetric disturbance developed. The pattern of the non-axisymmetric flow was similar to that of a polar air outbreak.A heavy rainfall associated with the Baiu front was observed during an intensive observation period in the Kyushu District in July 1988. We studied a structure and mechanism of a rainband caused the heavy reinfall. A retrieval method was developed to reveal a thermodynamic field in the rainband. The retrieved field showed that the evaporation of raindrop and a vertical shear were important to maintain the intense rainband.^1 "ORI" is the abbreviation of "Ocean Research Institute".A numerical prediction experiment of the heavy rainfall was performed. The observed rainfall was simulated well and the environmental condition of the rainfall was studied. A numerical model with high horizontal resolution was used to find a detailed structure of the heavy rainfall. The rainband was simulated and its vertical structure was clarified.

极地空气质主义在亚洲大陆以东的日本天气中占主导地位。在极性气气和热带气气之间形成的Baiu和Akisame前部与极性气气的活动有关。极地气泡的不规则行为有时会导致日本异常的天气。这项研究的目的是由于极性空气质量的不规则活性和相关的大降雨而导致的异常天气。通过统计方法，分析了NMC网格点数据，以研究极地空气质量的活性。在夏季，在南半球和冬季北半球的夏季，在500HPA高度领域发现了高度相关性。与北半球相比，南半球的高度异常在区域方向相对均匀。虽然旋转设备是轴对称的，但轴对称流不稳定，并且会产生非轴对称干扰。非轴对称流的模式与极地空气暴发相似。开发了一种检索方法来揭示雨带中的热力学领域。检索到的领域表明，雨滴和垂直剪切的蒸发对于维持强烈的雨带很重要。^1“ ori”是“海洋研究所”的缩写。进行了重雨的数值预测实验。对观察到的降雨进行了很好的模拟，并研究了降雨的环境状况。使用高水平分辨率的数值模型用于查找大降雨的详细结构。模拟了雨带，并阐明了其垂直结构。