s s Wind-induced circulation The wind-induced circulation can compete with estuarine circulation, or act in concert The wind-induced circulation will depend on stratification: depth-dependent under stratified conditions weak depth-dependence under homogeneous conditions s Weak Depth-Averaged Transport s Large Depth-Mean Transport

sx Wind-Induced Surface Slope Can be assessed from the vertical integration of the linearized u momentum equation, with no rotation @ steady state: Note that a westward sx (negative) produces a negative slope. sx x1 x2 y x x1 x2  Wind will pile up water in the direction toward which it blows.

The perturbation produced by the wind propagates into the estuary and may cause seiching if the period of the perturbation is close to the natural period of oscillation: H H

Bathymetry effects on wind-induced flow non-dimensionalized momentum balance: non-dimensional variables: subscript indicates dimensional variables boundary conditions Integrating twice and applying boundary conditions:

volume transport no net volume transport

Along the Estuary: Pressure Gradient + Friction Winant (2004) Along the Estuary: Pressure Gradient + Friction Across the Estuary: Pressure Gradient + Friction

X t ROMS (full dynamics) Homogeneous fluid with rotation Sanay & Valle-Levinson (2005) ROMS (full dynamics) Homogeneous fluid with rotation (red is downwind; blue is upwind)

Particle trajectories (high E) (low E) (high E) (low E) y x y z y x y z Particle trajectories Winant (2004)

t Examples of bathymetric effects on wind-induced flow Looking into lagoon Red = Water going out Blue = Water going in

Non- dimensional depth

Residual Flow at Bahía Concepción, Chile (looking seaward)

Along the Estuary: Pressure Gradient + Friction Wind-induced flow [Wong, 1994; JGR; No. 99, p.14209] Local Wind Effects Remote Wind Effects Along the Estuary: Pressure Gradient + Friction