Some Aspects of Diurnal Variation and Profile of Vertical Turbulent Diffusivity in the Atmospheric Boundary Layer

Abstract

   The vertical turbulent diffusivity K_z in the atmospheric boundary layer was calculated from the trajectory data of the South Kanto Plain Project, the Akita Bay Area Experiment, and the Eastern Tennessee Trajectory Experiment, on the basis of the statistical theory of turbulence. And the seasonal and topographical effects affecting the diurnal variation and profile of K_z were investigated.
   In consequence, it was found as expected that K_z has a diurnal variation like a sine curve without regard to season or topography. It can be conjectured that the phase of diurnal variation is affected by the possible duration of sunshine, and the amplitude by topography and stability of the atmospheric boundary layer.
   The maximum vertical turbulent diffusivity K_max was observed within the region of 0.15≤z/z_i<0.50 on the K_z profiles throughout the whole data. And z_m at which K_max was observed differed with season and topography.