摘要
利用中尺度数值模式ARPS,在理想条件下研究了旋转、地表摩擦的共同作用下,均匀来流条件下,三维层结大气中地形上空及其边界层结构特征。重点讨论了不同的山地流动Fr数、不同上游来流方向情况下,山地流动及其边界层的特征。在大气稳定层结条件下,山地流动具有上游阻挡、下游急流加速以及重力波破碎等流动特征,这些山地流动特征在柯氏力的影响下,均表现出了南北非对称性。当山地流动的Fr数增加(增加地形高度)时,山地流动的南北急流增强,由于柯氏力的影响,南侧急流的增幅更为显著,流动的南北非对称性增强。在干过程山地流动中,由急流所导致的强烈的垂直风切变,是湍流边界层产生和发展的直接决定因素。
Under the conditions of hydrostatic, geostrophic balance, and uniform west wind, the stratified flow over a three-dimensional （3D） elliptical mountain is simulated by a storm-scale numerical model （ARPS）. In this paper a series numerical experiments were conducted to study the impacts of the mountain Fr number and the upstream flow orientation on the flow over three-dimensional mountain and the downstream boundary layer structure. The flow over 3D mountain is characterized by a string of phenomena, such as upstream block, downstream acceleration and gravity wave breaking and so on. Owning to the effect of Coriolis, these characters all become to be asymmetric. When the Fr number （ mountain height） is increasing, the stronger upstream block, downstream jets and more asymmetric flow pattern over mountain are produced, especially the south orographic jet benefits more from the Fr number increase. In the dry flow over mountain, the boundary layer TKE is dominated by the low-level vertical wind shear of mountain flow.
出处
《气象科学》
CSCD
北大核心
2008年第2期168-175,共8页
Journal of the Meteorological Sciences
基金
国家自然科学基金项目(40325014
40333031)
FANEDD(200325)和TRAPOYT
关键词
地形流动
Fr数
柯氏力
边界层
Flow over mountain Fr number Coriolis effect Boundary layer
