亚洲夏季风结构和变动与大气运动流场的斜压和正压特征:正压模分析

THE STRUCTURE AND VARIATIONS OF ASIAN SUM MER MONSOON REVEALLED BY BAROTROPIC AND BAROCLINIC MODES: THE BAROTROPIC CHARACTERISTICS

使用ＥＣＭＷＦ１９８０—１９８６年７ａ格点资料对大气运动的正压模进行了分析。指出：对流层中大气正压运动流场显示的副热带高压带仅能反映出行星风带的季节性移动；与亚洲夏季风有关且反映季风局地性的则是副热带高压带南侧的东风带上的波状扰动；东风带上的经向风分量存在着纬向传播且传播方向和扰动幅度与印度、东亚季风子系统有关；随着北半球夏季的到来，亚洲季风区大气运动的斜压模有较大的增长且斜压运动动能占气柱内整层平均总动能的绝大部分，而在赤道附近的其他经度上则是正压运动动能的成分明显增长。

By using the observational data, the relationships between the barotropic mode of the atmosphere and the structure/time evolution of Asian summer monsoon have been investigated. It is pointed out that the subtropic high belt revealled by barotropic mode of air flow in troposphere can only show us that the planetary wind belt moves seasonally in meridional direction.Something which is associated with Asian summer monsoon and makes us know where the summer monsoon could probablely be is the wavelike disturbance on eastlies of subtuopic high.Both the directions in which the meridional component of barotropic flow in eastlies propagates zonally and the amplitude of meridional wind disturbances are closely related to the subsystems of India and East Esian monsoon.When summer comes,the baroclinic mode grows rapidly in Asian monsoon area.The main part of total kinetic energy averaged over a whole air column in troposphere is the energy of baroclinic motion.In equatorial region beyond the monsoon area,the barotropic mode grows quickly when the summertime is coming in Northern Hemisphere.