抄録
Turbulent mixing process during nocturnal periods was investigated in urban area. Measurements of turbulence within and above a surface layer were conducted using Doppler lidar, sonic anemometer, and radiosonde in an urban residential area, Koganei, Tokyo, in February and October 2010. Vertical distribution of the vertical velocity was observed at the height from 59 m to about 1,000 m. The mixing process in the surface layer strongly depends on the atmospheric stability. Outer-layer turbulence hardly contributes to the development of the surface layer in the stable condition even though there still remains a residual turbulence or a downward flow from clouds. Meanwhile, the turbulent mixing extends up to 300 m from the ground in near-neutral atmospheric condition. We also observed that a low-frequency vertical motion in outer-layer correlated negatively with horizontal velocity, which is rather than vertical velocity, near the ground under near-neutral stratification.
