Climate Research
Freie Universität Berlin
Institut für Meteorologie
We use direct numerical simulation to investigate turbulent Ekman flow as a model for the planetary boundary layer. In some conditions frequently encountered in the real world, the ubiquitously accepted omni-presence of turbulence is no longer possible and a regime is encountered, where large non-turbulent or weakly turbulent partitions are encountered in an otherwise turbulent flow. This regime is not accessible by other modelling tools such as Large-Eddy simulation or Reynolds-Averaged tools as these assume homogeneous presence of turbulence. This regime is also very hard to access by observations as flux and field measurements in such very stable conditions are scarce for numerous challenges from the observational perspective. By using a novel simulation approach to this pressing problem in boundary-layer meteorology, we aim to fill in a gap and provide a consistent understanding of turbulence across the different regimes of stable turbulence.