Characteristics of the Atmospheric Boundary Layer at Different Scales TASSOFRANCISCO ANDRES LANG 2019 The behaviour of the atmospheric boundary layer at different scales is described with an emphasis on the largest contributions to the total turbulence kinetic energy. First, large sudden wind-direction shifts and submesoscale motions under very stable atmospheric conditions over land are examined. Second, we explore changes in the thermodynamic structure of the Marine Atmospheric Boundary Layer (MABL) over the Southern Ocean (SO) in relation to the synoptic meteorology. In the last part of this research, shipborne observations have been used to evaluate the WRF model, in simulating the MABL under cold front passages over the SO.