Fundamental limitations of using sensible heat flux as a lower boundary condition in stable boundary layer simulation and modeling

In single column and large-eddy simulation (LES) studies of the planetary boundary layer (PBL), surface sensible heat flux is often used as a boundary condition. In this presentation, we will delineate the major shortcomings of such a boundary condition in the context of stable boundary layer modeling and simulation. Using an analytical approach, we will show that any PBL model (single column or LES) will only be able to capture the near-neutral to weakly stable regime if surface sensible heat flux is prescribed. As a result, the modeled friction velocity will never become less than 67% of the neutral estimate for the friction velocity (in the case of the Businger–Dyer-type profiles). In order to represent the moderate to very stable regime in a PBL model, accurate surface temperature prescription or prediction (by a land-surface scheme) is needed.