Quasi-Oscillatory Processes of Louisiana Bay Flushing under Normal and Extreme Weather Conditions and their Relationships with Coastal Stratification and Hypoxia

The flushing of the Louisiana coastal bays, under normal and extreme weather conditions, are governed by quasi-oscillatory processes that constitute part of the land-ocean exchange and bay-ocean exchange. These exchanges provide freshwater, buoyancy, kinetic energy, and land-derived materials including nutrients and organic matter that establish variability in water column properties, including stratification and bottom-water hypoxia. The physical processes are shown to be the quasi-oscillations that result in the alternation between the strengthening and the destruction of stratification. Additionally, the formation and destruction of hypoxia also occur. The actual oscillations appear to be over broad spectrum, irregular, and location dependent; thus there is difficulty with interpretation in general. In our studies, these processes are examined using comprehensive sets of time series data from various sources along the Louisiana coast and long term moorings of the WAVCIS and LUMCON BIO2 instruments. The presentation and interpretation of our data are given in the context of the magnitude and time scales of bay flushing, atmospheric forcing, and coastal long waves such as tides and shelf waves. The oscillatory nature, correlations, phase relationships, and the time scales of examined parameters are shown to have predictable features (although limited) that can be useful for the understanding of the dynamics, model improvement, and model validation for coastal circulation, stratification and hypoxia dynamics.