We use large-eddy simulation (LES) technique to study atmospheric boundary layers (ABLs) under a wide range of stable conditions as they approach a quasi-steady state.
Due to excessive time requirements a few previously reported LES studies of stable ABLs did not reach the quasi steady state and the domain size was insufficient to fully resolve gravity waves. To overcome this problem we developed a parallel code. This enabled us to perform long-term simulations with a sufficient spatial resolution (more than 4 million grid points) and analyze the interactions between boundary layer turbulence and gravity waves in a quasi-steady state.
We used the Beaufort Sea Arctic Stratus Experiment (BASE) and the Surface Heat Budget of the Arctic Ocean (SHEBA) data sets to impose initial and boundary condition in order to numerically simulate clear-air stably-stratified ABL characterized by a strong inversion. Such ABLs are common occurrence in the Arctic. In a series of a low-resolution simulations we explored the parameter space by varying: latitude, surface cooling rate, geostrophic wind, inversion strength and surface roughness. In our simulations we observed the development of features characteristic for a stably stratified ABL: elevated inversions, associated inversion wind maxima (low level jets) and gravity waves. We studied the dependence of the boundary layer height on the flow parameters. We also analyzed global intermittence under strongly stable conditions