Daytime Temporal Variation of Surface-Layer Parameters and Turbulence Kinetic Energy Budget in Topographically Complex Terrain Around Umiam, India

We present the temporal variation of surface-layer parameters and the turbulence kinetic energy budget over complex terrain during daytime. Data from three-dimensional fast response sonic anemometers at heights 6 m, 18 m, and 30 m above the ground are used for the analysis. Mountainous topography induces wind-direction variability over the measurement site throughout the day, which significantly influences the diurnal evolution of sensible heat flux, momentum flux, and turbulence kinetic energy. The increase and decrease of turbulence kinetic energy rely on the various production and consumption terms. Buoyancy dominates in the morning whereas in the afternoon both buoyancy and shear production contribute equally for the turbulence kinetic energy. The turbulence kinetic energy budget is also influenced by horizontal advection at the station. The correlation between turbulent decay and buoyancy (shear production) is negative (positive) in free convective conditions in the morning, whereas no correlation is observed for mixed convective conditions in the afternoon.