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Dynamical characteristics of monsoon circulation and its modelling

季风环流的动力特征及其模拟

基本信息

批准号：
61460047
负责人：
KIMURA Ryuji
金额：
$ 2.05万
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：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-61460047/
关键词：
monsoon cold air-mass shiberian high northwest seasonal wind 温帯低気圧

项目摘要

Monsoon is the atmospheric circulation driven by temperature difference between lands and oceans. The dynamics is controlled by 1)density stratification of the atmosphere, 2)differential heating at the lower boundary, 3)diffusion proces of heat and momentum, 4)Coriolis force and 5)seasonal variation of the temperature contrast between lands and oceans. In this study hydrodynamic characteristics of the atmosphere subject to these factors have been investigated by a linear theory and a laboratory experiment. The objective of the linear theory is to determine the horizontal scale of the circulation produced by differential heating. It was found that the horizontal scale is given by N K^<1/2>w^<-3/2>F(f/w), where N is the buoyancy frequency, K is the diffusion coefficient, w is the angular frequency of the thermal forcing and f is the Coriolis parameter. In the laboratory experiment we investigated effects of the rotation to the flow pattern: When the rotation rate is small, the circulation is axisymmetrical without any frontgenesis. When the rotation rate exceeds a critical value, it turns out to be wavy due to barolinic instability. Formation of the cold front takes place in the unstable situation. The behaviour showed remarkable similarity to that of the actual cold front observed in the atmospehre.

季风是由陆地和海洋温差驱动的大气环流。大气密度层结、下界差热、热量和动量的扩散过程、科里奥利力和陆地与海洋温差的季节变化控制了这一动力。在这项研究中，我们用线性理论和实验室实验研究了受这些因素影响的大气水动力特性。线性理论的目的是确定差热产生的环流的水平尺度。结果表明，水平尺度由N K^&lt；1/2&gt；w^&lt；-3/2&gt；F(f/w)给出，其中N为浮力频率，K为扩散系数，w为热力的角频率，f为科里奥利参数。在实验室实验中，我们研究了旋转对流型的影响：当旋转速度较小时，环流是轴对称的，没有任何锋生。当旋转速度超过一个临界值时，由于压力不稳定，它被证明是波状的。冷锋的形成是在不稳定的形势下发生的。这种行为与在大气层中观察到的实际冷锋的行为非常相似。