Comparison of the Convective Boundary Layers of the Atmosphere and the Ocean Simulated by LES

Both convective boundary layers (CBL) in the atmosphere and the ocean, are characterized by the well-mixed layer with strong entrainment at the inversion layer/the mixed layer depth, which is driven by large-scale convective eddies. Therefore the same vertical mixing scheme used in the atmospheric boundary layer (ABL), such as the K-profile model, is often applied to the ocean mixed layer (OML) as well. Nonetheless the presence of the free surface makes the OML fundamentally different from the ABL in many aspects. It generates many features unique in the OML such as wave breaking, Langmuir circulation, and inertial oscillation. For example, wave breaking causes the turbulent kinetic energy (TKE) becomes very large near the surface in the OML, whereas it becomes very small in the ABL. Therefore, with an aim to understand the difference in the mixing process, we compare the CBLs of the atmosphere and the ocean, by analyzing LES results obtained under various conditions of different surface forcing and initial profiles. We compare the various vertical profiles of TKE, velocity, temperature, stratification, shear, and heat flux, the TKE budget. We also compare the entrainment rate, the effect of the Coriolis force, and the probability distribution of vertical velocity. Particular interest is given to how the different features of the CBL can affect the parameterization of vertical mixing, such as nonlocal mixing and entrainment rate.