On the Structure and Adjustment of Inversion-Capped Neutral Atmospheric Boundary-Layer Flows: Large-Eddy Simulation Study
- 501 Downloads
A range of large-eddy simulations, with differing free atmosphere stratification and zero or slightly positive surface heat flux, is investigated to improve understanding of the neutral and near-neutral, inversion-capped, horizontally homogeneous, barotropic atmospheric boundary layer with emphasis on the upper region. We find that an adjustment time of at least 16 h is needed for the simulated flow to reach a quasi-steady state. The boundary layer continues to grow, but at a slow rate that changes little after 8 h of simulation time. A common feature of the neutral simulations is the development of a super-geostrophic jet near the top of the boundary layer. The analytical wind-shear models included do not account for such a jet, and the best agreement with simulated wind shear is seen in cases with weak stratification above the boundary layer. Increasing the surface heat flux decreases the magnitude and vertical extent of the jet and leads to better agreement between analytical and simulated wind-speed profiles. Over a range of different inversion strengths and surface heat fluxes, we also find good agreement between the performed simulations and models of the equilibrium boundary-layer height, and of the budget of turbulent kinetic energy integrated across the boundary layer.
KeywordsInversion strength Large-eddy simulation Neutral atmospheric boundary layer Wind profiles
The study was supported by the Danish Council for Strategic Research, project number 2104-08-0025 named Tall Wind. We would like to thank Branko Kosović for valuable cooperation.
- Batchvarova E, Gryning SE, Skov H, Sørensen LL, Kirova H, Münkel C (2013) Boundary-layer and air quality study at “Station Nord” in Greenland. In: Steyn DG, Mathur R (eds) 33rd International Technical Meeting on Air Pollution Modelling and Its ApplicationGoogle Scholar
- Pedersen JG, Kelly M, Gryning SE, Brümmer B (2013) The effect of unsteady and baroclinic forcing on predicted wind profiles in Large Eddy Simulations: Two case studies of the daytime atmospheric boundary layer. Meteorol Z 22:661–674Google Scholar
- Rossby CG, Montgomery RB (1935) The layer of frictional influence in wind and ocean currents. Pap Phys Oceanogr Meteorol 3:1–101Google Scholar
- Taylor J, Sarkar S, Armenio V (2005) Large eddy simulation of stably stratified open channel flow. Phys Fluids 17:116602Google Scholar
- Wyngaard JC (2010) Turbulence in the atmosphere. Cambridge University Press, New York, 392 ppGoogle Scholar