(1) Meteorology and Air Quality, Wageningen University, Duivendaal 2, 6701, AP, Wageningen, The Netherlands
Abstract:
We study the relation between fluxes and gradients in the very unstable surface layer by comparing recent proposals in the
literature with the well-known Businger–Dyer functions. The recent proposals include results from large-eddy simulation (LES),
which account for entrainment effects and effects of the boundary-layer depth. A comparison of the relationships is made with
experimental data. The LES-based gradient functions show the impact of entrainment in the surface layer, but the scatter in
the field data is too large to confirm this. Therefore this result is preliminary and future tests against new observations
are recommended. It appears that the Businger–Dyer relationship behaves differently to the alternatives, and that it deviates
from observations for large stability.