南京南郊大气湍流统计特征的实验研究

Statistic characteristics of atmospheric turbulence over southern suburbs of Nanjing

利用2011年8月南京南郊溧水大气边界层加强实验站的大气湍流观测资料,分析了城市郊区自然状态下垫面大气湍流宏观统计规律,以及湍流动量、热量、水汽和CO2的湍流输送特征。结果表明:不稳定层结下,3方向风速归一化标准差σu/u*,σv/u*,σw/u*,随稳定度参数ζ呈1/3幂次关系;稳定层结下也呈现类似规律;近中性条件下,分别趋近于常数。不稳定层结下,温度、比湿、CO2质量浓度归一化标准差σT/|T*|,σq/|q*|,σρCO2/|ρCO2*|,随ζ呈1/3幂次负相关关系,但结果相对离散,并且相对离散的数据对应着较小的|T*|、|q*|、|ρCO2*|值;稳定层结下,三者ζ之间的关系没有明显变化规律。实验期间相对于感热通量,潜热通量在热量平衡中所占比例较大;CO2通量平均值为负,整体表现为碳汇。水汽、热量和CO2均存在水平输送。

Based on the turbulence observations from Lishui experiments station in southern suburbs of Nanjing in August 2011, the macroscopic law of atmospheric turbulence on underlying surface in natu- ral state in suburbs and the statistical characteristics of momentum fluxes, latent heat fluxes, sensible heat fluxes, water vapor and carbon dioxide are investigated. The results showed that： in unstable condi- tion, relation between non-dimensional wind speed components and follows ＂1/3 power law＂, which is similar in stable condition. The wind speed normalized standard deviation is close to constant under near -neutral condition.In unstable condition, the normalized standard deviation of temperature, humidity and carbon dioxide fluctuation supports Monin-Obukhovsimilarity theory with much of scatter due to low values of ｜T＊ ｜,｜ q＊ ｜and ｜pco2,＊｜. However, no obvious variation regulation exists in stable condition. For the sensible heat fluxes, the latent part takes a large percentage in the heat balance in August 2011. The mean value of carbon dioxide fluxes transferring up and down in daytime but inversely at night is below 0,indicating that the southern suburbs of Nanjing is a carbon sink. Heat, water vapor and carbon dioxide all display the horizontal transportation phenomena.