由中尺度风温场模拟湍流属性特征量  

SIMULATION OF TURBULENCE CHARACTERISTIC QUANTITIES BY MESOSCALE WIND AND TEMPERATURE FIELD

作　　者：许丽人[1] 赵鸣[1] 李宗恺[1] 

机构地区：[1]南京大学大气科学系,江苏南京210093

出　　处：《南京大学学报（自然科学版）》2000年第6期750-759,共10页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(49875005,49735180)

摘　　要：主要讨论了由中尺度模式中输出的风、温场用完全的二阶闭合方法 ,求取湍流二阶矩量 ,进而求得方差、湍流强度等湍流特征量 ,研究这些湍流特征量的时空分布规律 .利用中尺度模式输出的风、温场 ,对不同下垫面上的湍流量的性质进行分析研究 ,以便进一步了解中尺度系统中湍流结构的物理特征 ,对研究大范围的污染物的扩散很有帮助 .研究结果表明模拟的湍流特征量符合已知规律 :湍流强度有明显的日变化 ,湍流强度与下垫面的粗糙度有关 ,粗糙度大的地区 ,湍流强度也大 ;平坦地区 ,湍流强度小 ;湍流强度与稳定度有关 ,不稳定情况下的湍流强度比稳定情况下的湍流强度来得大 ,并进一步分析了不同稳定度下的归一化湍流速度标准差的廓线 ,也符合已知的观测及边界层模式对湍流量的模拟结果 .方法为用中尺度模式预报风、温场诊断湍流场提供了一个有效的方法 .A new method to forecast the turbulence quantities is explored in this work. In order to calculate the turbulent second order moment, the second order closure scheme is used in the mesoscale model MM4. With the wind and temperature field output from MM4, the turbulence characteristic quantities, such as variance, turbulence intensity and so on, are calculated and the temporal and spatial distribution rules of the turbulence quantities are studied. In addition, the characteristics of turbulence on different underlying surfaces are analyzed with the intent to study the physical characteristics of the turbulence structure in the mesoscale system. The results show that the simulated turbulence intensities have obvious diurnal variation and are related to the roughness of the underlying surface and the stability of the atmosphere. The greater the roughness and the more unstable the atmosphere, the stronger the turbulence intensity. All these results agree with the common rules quite well. In this paper, the profiles of the normalized turbulence standard deviation in different stabilities are also analyzed. They are also in agreement with the observations and the simulated results by the boundary layer model. The consistency of results gotten by the new method with the common rules shows that the new method developed in this paper is feasible. With the new method, we can get the turbulence quantities from the observational data or from the mesoscale model. These turbulence quantities, on the one hand, can be used to analyze the features of the turbulence structure under different weather conditions. On the other hand, they are of great help to understand the diffusion characteristics in the atmospheric boundary layer, which play an important role in the large-scale pollutant diffusion.

关 键 词：中尺度模式 二阶闭合 湍流特征量 湍流结构 

分 类 号：P425.2[天文地球—大气科学及气象学] P435