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PhD Proposal Defense of Jianxing Wang
April 16 @ 10:00 am - 11:00 am
Wind Effects on Estuarine Circulation and Salinity Distribution
| Most research on estuarine dynamics to date has focused on tides as the main driver of vertical mixing. There has been less work on the role of wind, despite early predictions of first-order effects on mixing and observational evidence of significant wind-driven flows in estuaries. Our work on Neuse Estuary in chapter 1 found out that moderate down-estuary directed wind in the lower Neuse increases the exchange flow, leading to increased stratification and decreased bottom DO while strong down-estuary wind erodes the stratification and mixes the water column. Up-estuary wind inhibits and sometimes reverses the exchange flow, which reduces stratification and enhances vertical mixing. Cross-estuary wind in the lower Neuse drives lateral circulation, which tilts isohalines, decreases stratification, and enhances mixing. All these studies have focused on wind stress oriented directly along or across estuaries whereas wind can come from any direction. The response of estuarine circulation and salinity distribution to winds with both along- and across-estuary components, and in particular the effect of wind-driven lateral circulation on the along-channel exchange flow and salinity distribution have not been addressed previously and will be investigated in the proposed work in chapter 2. The geometry of estuaries can be complex and the effects of geometry on wind-driven circulation and associated salinity distribution have not received much attention. Channel curvature has been shown to lead to secondary (lateral) circulation in tidally-dominated estuaries but it has not been studied in wind-driven systems. Also, in an estuary in which channel orientation varies along its length, the wind stress could be along-estuary in one leg and across-estuary in a connecting leg, with a transition in between. Wind-driven secondary circulation and the interaction of momentum and salinity dynamics between two legs will be investigated in the proposed work in chapter 3. |
