Some Physical Factors That May Affect Turbulent Mixing in Altamaha Sound, Georgia

Abstract

A directed studies research project to understand turbulent mixing processes in Altamaha Sound has been carried out as part of the Georgia Coastal Ecosystems Long Term Ecological Research (GCE-LTER) project. In this study we analyze the flow and salinity characteristics, which has a periodic component of stratification that interacts with turbulent mixing to control water column stability. There is a contrast between the ebb and flood phases of the tides showing that during ebb, the water column is well mixed indicating that shear instabilities give rise to turbulent mixing and that during flood, density gradients stabilize the variations caused by the current shear. These results are contrary to tidal straining theory and are hypothesized to be related to shoaling surrounding the Altamaha channel towards the ocean. Because of shoaling, surface gravity waves may play a key role in enhancing bottom stress variability during flood flow. The physical factors that control turbulence in the coastal ocean are very important for understanding the mixing of water masses and thus the distribution of chemical, biological and physical properties that directly affect water quality.