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The Study for Spatial Structures and Time Development of Turbulence in the Atmospheric Boundary Layer

大气边界层湍流的空间结构和时间发展研究

基本信息

批准号：
13640437
负责人：
HORIGUCHI Mitsuaki
金额：
$ 2.3万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

In this study, the spatial structures and time development of turbulence was investigated using observations and numerical experiments for the neutral stability condition.At first, observed data at Shionomisaki Wind Effect Laboratory and Shigaraki MU Observatory was analyzed. To make an averaged pattern for the area of strong wind, continuous wavelet transform in the time scale of 160 seconds was applied to the wind component in mean wind direction measured at a height of 20 meters. The structures of the downward moving high-speed area and upward moving low-speed area ahead of it are shown.To execute numerical experiments, the ARPS (Advanced Regional Prediction System) developed by the CAPS (Center for Analysis and Prediction of Storms) at the University of Oklahoma was used for the large eddy simulation. For the initial condition, random potential temperature perturbation was induced on the horizontally homogeneous filed which has a wind profile with the log-linear wind law below the 30 meters and the Ekman spiral above it and an almost neutral potential temperature profile with uppermost inversion layer. After the integration time of 35040 sec., streaky structures elongated in mean wind direction are outstanding near the surface. Wavelet variance for the wind component in mean wind direction at a height of 7.5 meters is maximum at the spatial scale of 720 meters. Averaged pattern around the peak position for the wavelet variance shows the downward moving high-speed area from the height of about 150 meters. The area in length of 600 meters in mean wind direction and 240 meters in normal direction shows larger momentum flux than other areas below the height af 300 meters.

本研究通过观测和数值试验，对中性稳定条件下湍流的空间结构和时间发展进行了研究。首先，分析了盐之崎风效应实验室和茂木MU天文台的观测资料。为了对强风区域进行平均化，将160秒时间尺度上的连续小波变换应用于20米高度处测量的平均风向的风分量。利用俄克拉荷马州的CAPS（Center for Analysis and Prediction of Storms）开发的ARPS（Advanced Regional Prediction System）软件进行了大涡模拟，并进行了数值试验。对于初始条件，随机位温扰动是在水平均匀场上引起的，该场具有30米以下的对数线性风律和Ekman螺旋线，以及具有最高逆温层的几乎中性的位温廓线。在35040秒的积分时间之后，在近地面，沿平均风向拉长的条纹状结构十分明显。在7.5米高度的平均风向上的风分量的小波方差在720米的空间尺度上是最大的。小波方差的峰值位置周围的平均图案显示了从约150米高度向下移动的高速区域。在平均风向600米和正常风向240米范围内的动量通量比300米以下的区域大。