抄録
We conducted continuous observation for three months using Doppler lidar to investigate characteristic of the spacing of streaky coherent structures which include horizontal roll vortex and streak above urban area, Tokyo. The spacing of streaky coherent structures was estimated from the power spectrum density of horizontal velocity fluctuation. The spacing normalized by boundary layer height decreases with decreasing atmospheric stability In stable condition, and varies in a wide range under weakly unstable condition. A remarkable finding is that normalized local wind shear can consistently explain the normalized spacing of streaky coherent structures developed under stable, neutral and unstable conditions. In other words, local wind shear plays a significant role to decide spacing of such streaky coherent structures as horizontal roll vortex and streak.
