湍流湿度脉动特性研究——根据淮河流域实验资料

STUDY ON THE CHARACTERISTICS OF TURBULENTMOISTURE──BASED ON THE DATA OBTAINED FROM HUAIHE RIVER BASIN EXPERIMENT

利用淮河流域实验得到的湍流湿度脉动资料 ,应用统计理论、Fourier分析和小波分析方法 ,对湍流湿度脉动的统计特征、谱特征和间歇性特征作了初步分析 .结果表明 :(1 )在淮河流域这样的高湿地区 ,水汽对其地表能量平衡 ,能量输送与循环具有重要作用 ;(2 )湍流湿度脉动的能谱和互谱在惯性副区基本符合“ - 2 /3”次律和“ - 4/3”次律 ;(3 )淮河流域湍流湿度脉动场存在很强的间歇性 ,不符合Kolmogorov湍流理论 .利用离散正交小波变换将湍流湿度脉动场中的耗散事件分离出来 ,通过引入限制因子 ,将湍流脉动场中的耗散事件滤去后 ,能较好地抑制湍流湿度的间歇性 .但与风速脉动相比 ,湍流湿度场间歇性的抑制效果较差 .

In this paper, with the methods of statistical theory, Fourier transform and wavelet transform, the turbulent moisture data obtained from Huaihe River Basin Experiment (HUBEX) has been studied to explore the statistical, spectral and intermittent characteristics of turbulent moisture. The results show that: (1) In the high humid area such as Huaihe River Basin, the moisture plays an important role in the surface energy balance, energy transportation and cycle. (2) The energy spectra and cospectra are in agreement with the ' -2/3' and ' -4/3' scaling law correspondingly in inertial sub-range. (3) The fluctuating moisture field has strong intermittency, and is not in accord with the Kolmogorov theory. With the orthogonal wavelet transform, the dissipative events of the fluctuating moisture field contributing to inertial sub-range intermittency buildup have been identified. After the dissipative events have been suppressed by introducing a conditioning criterion, the intermittency that effects on the statistical structure of the inertial subrange is restrained. However the repressive effects of intermittency on turbulent moisture field are worse than that on turbulent velocity field.