DYNAMICAL CHARACTERISTICS OF THE STREAM FIELD OF COLD FRONT IN BOUNDARY LAYER

The motion equation of atmospheric boundary layer with cold front surface under geostrophicmomentum approximation is solved and some characteristics of the stream field for the cold frontsurface in the boundary layer are derived,for example,the slope of the cold front surface increaseswith the increases of geostrophic vorticity and the temporal tendency of geostrophic wind speed,and also increases with the decrease of the component of thermal wind speed along the motiondirection of the front:the stream field above and below the cold front surface in the boundary layerdepends on the slope of the front surface,geostrophic wind speed and its temporal and spatialdistributions.A common characteristic is that there exist updraft motion above the cold frontsurface and downdraft motion below it.     

考虑背景风压场影响的边界层数值模式

本文提出一个在中性情况下边界层数值模式中考虑背景风压场影响的方法。背景风压场的水平非均匀影响了边界层运动方程中的惯性力项及边界层的上界风速。本文把三维问题用一种线性化方法简化为一维问题，只要知道背景气压场的空间分布，即可求出考虑了背景场影响的边界层风场。     

非定常过程对大气边界层的内参数与风廓线的影响(二)

本文用大气边界层运动方程的数值积分研究了当边界层顶风向不变但风速变化时对大气边界层的内参数u_*/A(u_*为摩擦速度,A为上界风速)和α角(地面风与上界风向的交角)的影响。设上界处风速随时间指数增加及减少,最后趋于定常。在大气正、斜压时,u_*/A及α角的时间变化均是振幅衰减的振荡,最后趋于定常时相应的值。在时间变化过程中的任一时刻,内参数值与当上界条件取该时刻上界风时的定常解结果有一定的差别,严格说,定常时的内参数值并不能直接用于当上界风非定常时。本文还考虑了上界风速非定常对风廓线的影响。