南京夏季城郊湍流统计特性及湍流通量对比分析

利用2010年南京夏季城市热岛三维结构试验中的湍流观测资料,对南京市委党校和南京信息工程大学观测场2个观测点的湍流统计量和湍流通量进行了对比分析。结果表明：城市平均风速大于郊区;城郊2地的湍流强度都呈现出Ix〉Iy〉Iz的趋势,水平方向上的湍强城郊相差不大,而垂直方向上,郊区的Iz要明显低于城市;城、郊的风速归一化标准差σu/u＊、σv/u＊、σw/u＊都符合MoninObukhov相似理论的＂1/3＂定律,城市的垂直风速归一化标准差大于郊区,而水平方向上的风速归一化标准差则明显小于其他下垫面;郊区风速归一化标准差与常熟农田的拟合结果较为相似,而城市风速归一化标准差与长白山森林的拟合结果更为接近;夏季城市以感热通量为主,而郊区湍流能量的输送以潜热通量为主,且城市的湍流热通量受太阳辐射的影响更大。

Statistical Characteristics of Turbulence and Comparison of Turbulence Fluxes in Urban and Suburb of Nanjing in Summer

Based on the observational turbulence data from the three- dimensional experiments at urban and suburban sites of Nanjing in summer of 2010,the statistical characteristics of turbulence and fluxes were comparatively analyzed. The results showed that the average wind speed over urban surface was larger than that over suburb surface. The turbulence intensity Ixand Iyin the horizontal directions of urban and suburb was greater than Izin the vertical direction,and the Ixwas greater than Iy. The difference of Ixand Iybetween suburb and urban was small,but the Izof suburb was significantly less than that of urban. The wind speed normalized standard deviations σu/ u＊,σv/ u＊,σw/ u＊in urban and suburb could be fitted according to the‘law of 1 /3 fractional power＇,and the σu/ u＊andσv/ u＊in urban were obviously less than those in other areas,while the σw/ u＊was greater than that in suburb. And then the fitting curves of wind speed normalized standard deviations in suburb were similar with farmland. In summer,the latent heat flux was leading in suburb,while the sensible heat flux was leading in urban,and the influence of solar radiation on the turbulence heat flux in urban was larger than that in suburb.