Characteristics of Momentum and Scalar Flux in the Urban Boundary Layer
城市边界层动量和保守物通量的特征

Turbulent statistics(normalized standard deviations,higher order moments,fluxes and spectra and cospectra) in the urban boundary layer are analyzed with data collected from the Beijing 325 m meteorological tower from January to May,2005.Characteristics of spectra and cospectra indicate little influence of stability and more influence of horizontal wind speed on turbulent spectra.Therefore, the similarity relationships of velocity components and temperature is suitable for stable conditions.However,the similarity theory seems not to be fit for water vapor and carbon dioxide for they are affected by other factors.There are square relationships between their kurtosis and skewness.Furthermore,as for daily fluxes,carbon dioxide is different from water vapor,and daily carbon dioxide fluxes reflect the influence of human behavior.Furthermore,sensible heat fluxes,latent heat fluxes and carbon dioxide fluxes change with season.In particular,variance of latent heat fluxes can be very significant.