Impacts of climate change on estuarine stratification and implications for hypoxia within a shallow subtropical system
Citation:
Duvall, M., B. Jarvis, AND Y. Wan. Impacts of climate change on estuarine stratification and implications for hypoxia within a shallow subtropical system. Estuarine Coastal and Shelf Science. Elsevier Science Ltd, New York, NY, 279:14, (2022). https://doi.org/10.1016/j.ecss.2022.108146
Impact/Purpose:
In this paper, we develop a 3D hydrodynamic model for Pensacola Bay. The model was used to assess changes in Bay circulation and mixing under future climate change scenarios. Implications for future changes in seasonal hypoxia due to changes in vertical density stratification are discussed.
Description:
Vertical density stratification often plays an important role in the formation and expansion of coastal hypoxic zones through its effect on near-bed circulation and vertical oxygen flux. However, the impact of future climate change on estuarine circulation is widely unknown. Here, we developed and calibrated a three-dimensional hydrodynamic model for Pensacola Bay, a shallow subtropical estuary in the northeastern Gulf of Mexico. Model simulations based on years 2013–2017 were applied to examine changes in salinity, temperature, and density under future climate scenarios, including increased radiative forcing (IR) and temperature (T), increased freshwater discharge (D), sea level rise (SLR), and wind intensification (W). Simulations showed that the impacts of climate change on modeled state variables varied over time with external forcing conditions. The model demonstrated the potential for sea level rise and increased freshwater discharge to episodically increase vertical density gradients in the Bay. However, increased wind forcing destabilized vertical gradients, at times reducing the spatial extent and duration of stable stratification. For time periods with low freshwater discharge, moderate increases in wind speed (10%) can destabilize density gradients strengthened by increased discharge (10%) and sea level rise (0.48 m). In contrast, destruction of strong density gradients that form near the mid-Bay channel following flood events requires stronger wind forcing. These results highlight the importance of considering natural variability in freshwater and wind forcing, as well as local phenomena that are generally unresolved by global climate models.
URLs/Downloads:
DOI: Impacts of climate change on estuarine stratification and implications for hypoxia within a shallow subtropical system