The influences of orography upon the flow within Ekman boundary layer under the approximation of geostrophic momentum     

Wu Rongsheng 《大气科学进展》1985,2(1):1-7

In this paper, the influences of orography on the boundary layer flow with the approximation of geostrophic momentum are studied. The wind velocity at the lower boundary will not always be zero when the orography exists. So the structure of the boundary layer flow, as well as the vertical velocity at the top of the boundary layer, is affected. There are three factors affecting the vertical motion at the top of the boundary layer: lifting due to orography; divergence due to Ekman flow, and advection of the geostrophic momentum. These effects and the features of the flow within the boundary layer are discussed in detail.  相似文献   

ON WAVE PROPAGATION IN NON-UNIFORM MEDIA          下载免费PDF全文

Wu Rongsheng 《Acta Meteorologica Sinica》1990,4(2):248-253

In this paper,the results are analysed on wave propagation in non-uniform media which were studied by Lighthill,Whitham and some others.It is found that when the phase of wave is expressed as that of near plane wave i.e.θ=k(X,T)x-ω(kX,T),X,T)t where X=εx,T=εt,ε is a small parameter,k,ω are local wavenumber and frequency,then we can get ∂k/∂T+∂ω/∂X=∂Ω/∂X.This means that the phase does not satisfy the principle of continuity as proposed by them.With this result,it is pointed out that the wavenumber is always constant along rays while frequency is variable.This is different from that obtained by Lighthill and others.The causes for these differences are discussed in the paper.  相似文献   

EFFECTS OF OROGRAPHY AND AIR FLOW IN EKMAN BOUNDARY LAYER^*     

Wu Rongsheng 《Acta Meteorologica Sinica》1991,5(1):62-70

It is convenient to use σ-coordinates to discuss the dynamic effect of orography and the flow in Ekman boundary layer.In this paper,the theory of mixing length is generalized to the σ-coordinate system.Then the governing equations,describing the motion in the boundary layer over the mountain regions are derived.The features of flow in the boundary layer,especially the effects of Ekman pumping,are discussed indetails.It is pointed out that there are three factors affecting the vertical motion at the top of the boundary layer:(1) vorticity distribution in the boundary layer,which is directly related to the divergence and convergence of air flow caused by friction,(2) the upslope or downslope motion of flow over the mountain slopes,and(3) the mutual effect of orography and friction induced by the ageostrophic component climbing upward or downward in the boundary layer over mountain regions.  相似文献   

Petrographic Features and Sedimentary Environments of the Middle-Upper Ordovician at Shetai Town of Urad Front Banner, Inner Mongolia     

Zhang Xiulian  Wang Yinghua  Pan Rongsheng 《《地质学报》英文版》1991,65(4):401-416

Most of the hinterland of the North China platform is devoid of Late Ordovician strata. The BaiyanhuaMountain section at Shetai Town is a standard section of the Upper Ordovician newly established in recentyears at the northernmost margin of the platform. This establishment directly involved the determination of thenorth boundary of the platform and the understanding of its evolutionary Listory. The area is quite differentfrom the binterland of the platform in Middle Ordovician rock types and sedimentary environments, with theformer characterized by frequent slope deposits and the latter consisting almost entirely of platform deposits.The present paper focuses on the petrographic features and sedimentary ervironments of the Middle-UpperOrdovician strata in the area, providing further theoretical support to the establishment of the section and fil-ling the gap in this respect.  相似文献   

斜压性与非线性Ekman抽吸的动力特征     

谈哲敏  伍荣生 《气象学报》1992,50(4):403-412

本文利用Ekman动量近似研究了斜压性对Ekman层动力学的影响,得到了一些新的结果。大气斜压性对Ekman层的水平风速分布及近地面的风速矢的水平分量夹角有重要的改变作用。斜压边界层顶部的非线性Ekman抽吸(垂直运动)由三个不同的物理因子决定,第一、正压性的地面地转涡度,第二、斜压性作用产生的热成风涡度,第三、正压性的地面地转涡度与斜压性的热成风涡度的非线性相互作用。这些理论结果为边界层的参数化及数值模拟结果的解释提供物理基础。  相似文献   

关于非均匀介质中波的传播问题   总被引：3，自引：0，他引：3  

伍荣生 《气象学报》1989,47(1):1-7

本文中,对Lighthill等人有关非均匀介质中波动性质的研究进行了分析。在接近平面波的近似情况,位相并不满足他们提出的连续性原理,而频率随时间的变化成为位相变化的外源。同时沿群速线方向,波数总是守恒的,无论介质均匀与否,但频率在群速方向上总是改变的。这些结果和Lighthill等人的结果是有所差异的。在本文中,除给出了具体的表达式外,并对引起差异的原因作了分析,认为本文结果较为合理。  相似文献   

广义涡度与位势涡度守恒定律及其应用   总被引：19，自引：2，他引：19  

伍荣生  谈哲敏 《气象学报》1989,47(4):436-442

在文中推得了广义涡度守恒定律,并利用此定律在一般情况下求得了广义位势涡度定律。它放宽了最初Ertel的位势涡度定律的限制条件。并对涡度拟能、螺旋性守恒定律的物理意义作了讨论,这些定律能够描述大气运动的重要动力学性质。  相似文献   

The wind structure in planetary boundary layer     

Zhao Ming  Xu Yinzi  Wu Rongsheng 《大气科学进展》1989,6(3):365-376

The investigations on the dynamics of the PBL have been developed in recent years. Some authors emphasized macro-dynamics and others emphasized micro-structure of the PBL. In this paper, we study and review some main characteristics of the wind field in the PBL from the view point connecting the macro-dynamics and micro-structure of the PBL, thus providing the physical basis for the further research of the dynamics and the parameterization of the PBL.  相似文献   

遥感方法研究珠江口近二十多年来土地覆盖的变化     

李学杰  万荣胜 《南海地质研究》2006,(1):41-51

土地覆盖变化是全球变化研究的重点之一，尤其是河口地区，对环境变迁十分敏感。对珠江口东部地区1979年的Landsat MMS、1990年Landsat TM和2000年Landsat ETM影像的土地覆盖分类，并进行对比研究表明，此间，总体水域面积和绿地（包括森林和耕地）面积减少，建筑区和裸露地面积增加。但不同区域土地覆盖类型变化有明显的区别，西部主要是由于沉积作用和围海造地，造成水域面积减少，且20世纪90年代围海造地速率比80年代要大得多。东部海域沉积作用不是主要因素，局部海岸可能还存在侵蚀作用。交椅湾区水域面积变化不大，岸线位置也基本稳定，而且80年代的水域面积有所增多，是由于陆地人工水塘增多的结果。蛇口区主要是由于港口码头等建设，导致水域面积减少，码头向海域延伸的结果，90年代明显加大了码头建设的规模和速度。  相似文献   

碎石桩-CFG桩组合型复合地基设计理论与工程实践   总被引：1，自引：0，他引：1  

王贵和  季荣生  马孝春 《岩土工程技术》2006,20(5):248-251

结合具体工程实例,对碎石桩-CFG桩组合型复合地基的应用和设计计算方法进行了分析,提出了合理的计算方法。  相似文献