Structure of the Flow within the Coastal Boundary Layer of the Great Lakes

Abstract

Properties of the nearshore flow have been observed in some detail in Douglas Point, Lake Huron. Time series flow data obtained from a network of current meters deployed in a coastal chain perpendicular to the local shoreline have been analyzed to resolve the mean flow properties, horizontal turbulence characteristics and the kinetic energy (in the mean flow and fluctuations) within the coastal boundary layer. The variability of these parameters as a function of the distance from shore for an episode during which persistent short-parallel currents prevailed for several days has revealed two distinct boundary layers, an inner boundary layer dominated by bottom and shore friction (FBL?frictional boundary layer) and an outer boundary layer as a consequence of the adjustments of inertial oscillations to the lateral boundary (IBL?inertial boundary layer). If one takes the width of the frictional boundary layer as the distance to the point where the kinetic energy of currents peak, it is ?2 km at Douglas Point, Lake Huron. As the width of the inertial boundary layer, one may take the distance to the point where inertial oscillations begin to dominate shore-parallel flow. This width is ?8?10 km at Douglas Point, Lake Huron.