Speaker
Description
Atmospheric boundary layer (ABL) is a region is the lowest part of the Earth's atmosphere, where interactions between the surface and the atmosphere play a crucial role in shaping weather patterns, climate processes, and air quality. Stably stratified ABL, form mostly over night due to surface radiative cooling, they also prevail in the snow-covered polar regions. Under the stable stratification, air near the surface is cooler than the air above it, inhibiting vertical mixing. Turbulence within the stably stratified boundary layer is produced by shear, however, due to the negative buoyancy flux turbulent motions can be locally suppressed or significantly reduced. The characteristic features of the stably stratified ABL are the intermittency, non-stationarity and the presence of gravity wave motions. These additional complexities make turbulence parametrization challenging. In this work we study observational data from MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition and calculate terms in the budget of the turbulence kinetic energy. We focus in particular on the periods of turbulence decay and turbulence development. We calculate the non-dimensional dissipation coefficient and show that it varies significantly, especially during the transient periods. We put forward a parametrization scheme for the strongly stratified ABL and present its experimental verification.
