In recent years several airborne measurement campaigns have been conducted by the Alfred Wegener Institute to study boundary layer processes over the open and the ice covered arctic ocean. The aircraft was equipped with a turbulence probe, radiation sensors, a laser altimeter, a radiation thermometer, and further surface scanning cameras.The measurements form a basis for parameterization and model studies of convection over water, momentum transfer over the marginal ice zone and the closed pack ice and analyses of the boundary layer development after a change in surface conditions.Data from the convective boundary layer over water are used to show roll convection during a cold air outbreak and to present a parameterization of fourth order moments for convective conditions. Momentum transfer has been studied during low level flights over closed sea ice. The data are used to compare two concepts of roughness parameterization, based on a drag partitioning for ridges and surface, and based on statistics of the ice topography.