Large-Eddy Simulation of an Arctic stable cloudy boundary layer

We study an Arctic stable cloudy boundary layer observed over the SHEBA (Surface HEat Budget in the Arctic) ice camp on 23 July 1998 during the FIRE (First ISCCP [International Satellite Cloud Climatology Project] Regional Experiment) ACE (Arctic Clouds Experiment) using a large eddy simulation (LES) model. The cloud layer was surface based and located in a stable boundary layer below 250 m height, which is characterized by strong wind shear and a pronounced temperature inversion. Our simulations indicate that the model is able to provide reasonable mean profiles of the horizontal wind, temperature, humidity and cloud liquid water compared to those observed by aircraft, radiosonde and surface tower.

The budget of turbulent kinetic energy is analyzed based on our LES. Wind shear generates the turbulent kinetic energy within the cloud layer, while the buoyancy and viscous are the dominant energy sink. Sensitivity experiments also suggest that the turbulence of this boundary layer is driven primarily by wind shear.