2008 Volume 52 Pages 253-258
The present study investigated the relationship between the mean and instantaneous characteristics of turbulence within the atmospheric surface layer over urban like roughness. To make it, we compared the horizontal distribution of the turbulent fluctuations and the turbulent statistics, which are derived from the same data obtained in the facility of comprehensive outdoor scale model for urban climate (COSMO) .
It is known that the turbulent motion within the atmospheric surface layer is composed of active and inactive eddies. The active eddy is originated from the surface under neutral stratification and relevant to the turbulent transport process. The inactive eddy is attributed the mixing in the atmospheric boundary layer and irrelevant to the turbulent transport process. To evaluate the characteristics of active turbulence which reflects the characteristics of roughness, we decomposed the turbulent fluctuation into the active and inactive components. This analysis revealed that the streaky structure observed in COSMO is attributed to the active turbulence.
