Multiscale Turbulence in the Atmospheric Boundary Layer

Turbulent flows are widely observed in nature and man-made systems. The understanding of turbulence is important since the air motion in the atmospheric boundary layer is essentially turbulent at high Reynolds numbers with spatial scales ranging from millimeters to kilometers. In particular, the Earth's energy, water and carbon budgets are constrained by turbulent fluxes of momentum, heat, water vapor and CO2 in the atmospheric surface layer, which are key for improved hydrological, weather, climate and carbon cycle prediction. Moreover, climate models are highly sensitive to the representation of turbulence in the atmospheric boundary layer, which is thus important for the projections of future climate. Some few exact and nontrivial hypotheses or theories form the basis of the understanding of turbulence, which are then applied in the modeling and parameterization, and field observations of turbulence. However, these hypotheses or theories do not always apply in the atmospheric boundary layer since some prerequisites are not always met. The main objective of this dissertation is thus to improve the understanding of turbulence in the atmospheric boundary layer and to correct key as