Infinite Boundary Element in Two and Three Dimensional Problems     

Yang Wei  Ge Xiurun 《岩土力学》1989,10(1):1-11

In this paper, the infinite boundary elements developed previously in two and three dimensional problems are reviewed, and the shortcoming and irrationality of interpolation functions of those elements are pointed out. A new interpolation function of infinite boundary element is proposed. The divergent integration on infinite element is also discussed in this paper.  相似文献   

小尺度地形阻塞作用的数值试验     

桑建国  龚威 《大气科学》1988,12(2):131-139

本文采用数值试验方法,讨论了一个高度只有200m的小尺度地形的阻塞作用,表明当大气低层的平均风速和温度层结使得Froude数小于1时,就有可能在地形的上风向形成阻塞。本文共试验了一般稳定层结、深厚逆温和浅薄逆温几种情况,讨论了数值结果和Froude数判别式之间的差异和原因,并计算了阻塞发生时的浓度分布。  相似文献   

热带气旋形成的多尺度组合理论——流体动力学实验模拟与合成分析的结合          下载免费PDF全文

魏鼎文  W.M.Gray 《大气科学》1988,12(2):200-207

结合流体动力学实验模拟(物理模型)与大量记录的合成分析,本文提出了热带气旋形成的多尺度组合理论。它强调了热带中尺度深厚对流云系的作用,同时它也着重说明了大尺度环境气流与小尺度积云对流的重要作用。 本理论可解释一些有关热带气旋以前所不能解释的观测事实,特别是它解释了热带气旋前期低压环流的形成。  相似文献   

青藏高原模式大气(暂用)   总被引：2，自引：0，他引：2  

魏丽  钟强 《高原气象》1988,(2)

本文根据青藏高原地区高空温、压、湿的气候资料并参考中纬度与热带模式大气初步建立了青藏高原不同季节的模式大气,以供该地区辐射传输研究的需要。  相似文献   

大气红外窗区(10.5-11.5μm和11.5-12.5μm)辐射传输的敏感性试验   总被引：1，自引：0，他引：1  

魏丽  钟强 《高原气象》1988,(3)

大气窗区卫星红外遥感的辐射资料可应用于地表温度的确定,但必须考虑大气影响。为此,本文利用辐射传输模式和中纬度及青藏高原模式大气,用数值模拟的方法研究了大气和地表状态(大气温、湿廓线、地表温度与高度)的改变对大气顶红外窗区射出辐射的影响以及射出辐射对发射方向(天顶角)依赖关系。主要结论见正文小结。  相似文献   

Analytic solutions to long's model: A comparison of nonhydrostatic and hydrostatic cases     

Mr. Qi Hu  Prof. E. R. Reiter  Prof. R. A. Pielke 《Meteorology and Atmospheric Physics》1988,39(3-4):184-196

Summary In this paper, analytic solutions of the nonhydrostatic and hydrostatic forms of Long's model were obtained under two different sets of vertical boundary conditions: The first uses a sumusoidal obstacle at the lower boundary and a rigid-lid top for the upper boundary. The second set applies an isolated obstacle of the Witch of Agnesi type at the lower boundary, while still using a rigid lid at the top. Following the solution evaluations, comparisons between the nonhydrostatic and hydrostatic solutions were processed in order to describe several influences introduced by using the hydrostatic assumption in this model.Through comparisons we have found that, in the case of a sinusoidal lower boundary condition, the hydrostatic solution is obtained as the zero mode of the nonhydrostatic solution. The influence of the hydrostatic assumption on the model solution is trivial in this case. When an isolated lower boundary condition is applied, however, the solutions illustrate dramatic differences, showing the significance of the effect of hydrostatic assumption on this model's solutions. These effects vary considerably with the model parameters as well. The comparison results also reveal that the realization of the hydrostatic assumption in this model's solutions is accomplished through the vertical boundary conditions used in the model evaluations.With 5 Figures  相似文献   

Characteristics of the temporal-spatial variation in atmospheric ozonosphere over the northern hemisphere during the period of 1963-1985     

Guo Shichang  Wei Dingwen 《大气科学进展》1988,5(3):361-368

The total ozone data of 113 ozone observational stations in the Northern Hemisphere (NH) spanning a period of 1963-1985 have been analysed in this paper. Some interesting results have been obtained, such as the temporal and spatial distribution, long-term trends, the harmonic analysis results, the relationship between the total ozone and solar activity, etc. Furthermore, by using the denned index G, the long-term changes of ozone meridional distribution patterns for the region of Europe-Asia (EA) have been approached particularly.  相似文献   

积雨云中微物理过程的数值模拟——(二)阵雨、冰雹、暴雨的个例研究   总被引：5，自引：2，他引：5       下载免费PDF全文

胡志晋  何观芳 《气象学报》1988,46(1):28-40

用文(一)的微物理模式在一维时变动力学框架里模拟了江西阵雨云,75·8暴雨和张家口冰雹云。用实测探空作为输入,计算结果同实测的云降水和雷达回波特征相比,在很多方面相当一致。它展示了暴雨云的持续性和冰雹云的低降水效率等,表明了在这些云底较暖的积雨云中贝吉隆过程对降水作用不大,而暖雨过程则是启动降水的主要环节。  相似文献   

倾斜固体潮对我国若干地震的触发作用浅析          下载免费PDF全文

刘光远  田少柏  王薇  吴建华 《地震工程学报》1988,10(4):45-50

本文研究了我国历史与现今中强以上地震的发震时刻与倾斜固体潮的关系。结果表明,地震发震时刻位于震中区当天倾斜固体潮的峰值时段上。孤立型地震的发震时刻往往与震中区倾斜固体潮极大值对应;原地重复发生的地震,其发震时刻所处的倾斜固体潮背景相同;逼近地震与主震发震时刻的倾斜固体潮背景相同的占70%;大震后有60%的强余震与主震发震时刻的倾斜固体潮背景相同。据此,成功地预报了门源6.4级地震后的较大余震。  相似文献   

Research on the regionalQ values of coda waves for the aftershocks in Luquan,Yunnan of 1985     

Jiazheng Qin  Ning Li  Kejian Hu 《地震科学（英文版）》1988,1(3):16-30

Based on the scattering coda model by which local and regional earthquakes are interpreted (K. Aki, 1969), and using observational coda data of 68 aftershocks of the 1985 Luquan, Yunnan earthquake registered by the VGK seismographs installed at 12 stations in the Yunnan regional short-period network, theQ-values of coda waves are calculated respectively for 6 time intervals. It is observed that within the frequency range of 0.40–1.65 Hz of the observed data, theQ-values are closely related with the frequencies and the calculated codaQ ranges between 80–240 with the coefficient of frequency dependence η=0.45. The calculated source factorsB(f> _p) of the coda waves which indicate the scattering strength are mostly within the order 10^?23–10^?24. Areas with lowQ-values present high scattering. It should be noted that by comparing data obtained before and after the Luquan earthquake, clear changes can be detected in theQ-values measured at stations close to the epicentral region, and that theQ-values of the aftershock coda are less than about one half of the pre-shock values. It may be mentioned that the time-dependent regional variations of theQ-values might possibly bring about practical significance in earthquake prediction. Moreover, aftershock focal parameters are determined. Through discussions on the quantitative relations between the focal parameters, we get: 1gE=1.59M _L+ 11.335;E=(2.10 × 10^?5)M ₀; length of focal rupturea=0.40?0.80 km for 3.0≤M _L<5.0 events; stress drop Δσ=(6.0–130) ×10⁵ Pa. Through interpretation of the data, we have also learned the important characteristics that there is no linear relation between the stress drops and the earthquake magnitudes.  相似文献