排序方式： 共有19条查询结果，搜索用时 0 毫秒
1.
采用与实测较接近的二次函数来表达Ｅｋｍａｎ层中的湍流粘性系数Ｋ，在圆形气压场条件下，求得了山地上空边界层中的风速，进而求得散度、涡度和垂直速度等场变量随高度的分布。并作图分析了这些场变量的一些动力学特征。改进了以往在求解析解时，略去运动方程中湍流粘性力项中的关于高度的一阶导数项，以及取山坡面上风速为零作下边界条件等欠合理欠精确的做法。所求得的风速、散度、涡度和垂直速度均用简单的初等函数表示出来，有助于边界层参数化和深化对边界层动力学的认识。 相似文献
2.
By use of geostrophic momentum approximation,the analytical expressions of the wind distributionwithin the planetary boundary layer and the vertical velocity at the top of the boundary layer are obtainedwhen the distribution of eddy transfer coefficient k is divided into three sections:k_1z(z_0≤z相似文献
3.
The investigations on the dynamies 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-stucture 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
4.
本文利用地转动量近似＾「１」并结合行波解的方法,研究了均匀基本气流中的层结大气非线性波动,首先由绝热无磨擦的闭合方程组导得关于垂直Ｐ速度的单一变量的非线性方程,然后讨论了非线性方程解的稳定性,并求得近似的非线性方程的椭圆余弦波和孤立波解及其存在条件。 相似文献
5.
在自由大气中,风压场之间基本上是满足地转平衡的,但在某些局部地区,可以出现地转偏差,而这些偏差通过惯性重力外波的频散作用将最终消灭而建立起地转平衡。这种适应过程已有很多的研究。与自由大气中的准地转气流的特征相似,在边界层中,在三种力即折向力、气压梯度力和湍流粘性力的平衡下,风场呈现Ekman气流,即风速矢量湍迹呈现Ekman螺线。类似于地转适应问题的提法,在边界层中,也存有Ekman气流的适应问题。即当初始场在某种原因下,风场、压力场之间与Ekman气流 相似文献
6.
7.
本文在半地转近似下,取湍流粘性系数k为三段式:k_1z(z_0≤z相似文献
8.
In considering the weak non-linear effect, and using the small parameter expansion method, the analytical expressions of the wind distribution within PBL (planetary boundary layer) and the vertical velocity at the top of the PBL are obtained when the PBL is divided into three layers and different eddy transfer coefficients K are adopted for the three layers. The conditions of barotropy and neutrality for the PBL are extended to that of baroclinity and non-neutral stratification. An example of a steady circular vortex is used to display the characteristics of the horizontal wind within the PBL and the vertical velocity at the top of the PBL. Some new results have been obtained, indicating that the magnitude of the speed in the lower height calculated by the present model is larger than that by the model in which k is a constant within the whole boundary layer, for example, in the classical Ekman boundary layer model and the model by Wu (1984). The angle between the wind at the top of the PBL and the wind 相似文献
9.
本文在ＷｕａｎｄＢｌｕｍｅｎ将地转动量近似引入行星边界层和ＴａｎａｎｄＷｕ＾「１」－「４」将地转动量近似发展为Ｅｋｍａｎ 量近似的工作基础上，在下 三方面作了改进； 相似文献
10.
在半地转近似［１］下，利用层结大气中的涡度方程、散度方程、连续方程和绝热方程结合行波解的方法得到了关于垂直速度的单一变量方程。这是与ＫｄＶ方程相应的非线性常微分方程，可得到椭圆余弦波或弧立波。此波动的频率有两种，表明层结大气中存在着两种性质不同的非线性波动。其一是东传的惯性重力椭圆余弦波，另一是混合Ｒｏｓｓｂｙ－重力椭圆余弦波，其性质介于Ｒｏｓｓｂｙ椭圆余弦波与西传的惯性重力椭圆余弦波之间。这两种非线性波的相速不但与波数和振幅有关，而且与β因子和静力稳定度有关，即纬度越低，则传播越慢；大气越稳定，则传播越快。 相似文献