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Estuarine circulation
Announcements Research groups Cruise dates Added another project – WC respiration Thursday: Thompson paper discussion
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Equations of motion, momentum (Navier-Stokes equations)
Momentum equations: Force/vol Pressure Coriolis Gravity Friction Dρu/Dt = ∂p/∂x + ρ2Ωvsin(φ) Kx(∂2ρu/∂x2+∂2ρu/∂y2+∂2ρu/∂z2 ) Dρv/Dt = ∂p/∂y - ρ2Ωusin(φ) Ky(∂2ρv/∂x2+∂2ρv/∂y2+∂2ρv/∂z2 ) Dρw/Ddt = ∂p/∂z ρg Kz(∂2ρw/∂x2+∂2ρw/∂y2+∂2ρw/∂z2 ) where Dρu/Dt = ∂ρu/∂t + u∂ρu/∂x + v∂ρu/∂y + w∂ρu/∂z Dρv/Dt = ∂ρv/∂t + u∂ρv/∂x + v∂ρv/∂y + w∂ρv/∂z Dρw/Dt = ∂ρw/∂t + u∂ρw/∂x + v∂ρw/∂y + w∂ρw/∂z (non-linear terms) Equation of Continuity: ∂u/∂x + ∂v/∂y + ∂w/∂z = 0 Number of unknowns: 7 (u, v, w, p, Kx, Ky, Kz) (velocities, pressure, eddy viscosities) Number of equations: 4 Turbulence closure: 3 equations to relate Kx, Ky, Kz to u, v, and w (This problem remains unsolved in a general way, but many approximate solutions exist)
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Pressure gradient terms
Barotropic fields Isobars and isopyncnals parallel Baroclinic fields Isobars and isopyncnals inclined Sea surface Isobar Isopycnal Level surface
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Estuary density gradients
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Estuary density gradients
Salinity distributions in Puget Sound South Sound Admiralty Inlet
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Ebbesmeyer et al.
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Estuarine circulation with sills
Thompson 1994
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Residual circulation Mean circulation after subtracting the oscillating tidal circulation Important for calculating mean transport in and out of Puget Sound
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PS mean circulation Ebbesmeyer et al.
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Instantaneous circulation
Several numerical models of Puget Sound circulation: Department of Ecology – South Puget Sound PNNL Salish Sea Model UW MoSSea King County model USGS model
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Equations of motion, momentum (Navier-Stokes equations)
Momentum equations: Force/vol Pressure Coriolis Gravity Friction Dρu/Dt = ∂p/∂x + ρ2Ωvsin(φ) Kx(∂2ρu/∂x2+∂2ρu/∂y2+∂2ρu/∂z2 ) Dρv/Dt = ∂p/∂y - ρ2Ωusin(φ) Ky(∂2ρv/∂x2+∂2ρv/∂y2+∂2ρv/∂z2 ) Dρw/Ddt = ∂p/∂z ρg Kz(∂2ρw/∂x2+∂2ρw/∂y2+∂2ρw/∂z2 ) where Dρu/Dt = ∂ρu/∂t + u∂ρu/∂x + v∂ρu/∂y + w∂ρu/∂z Dρv/Dt = ∂ρv/∂t + u∂ρv/∂x + v∂ρv/∂y + w∂ρv/∂z Dρw/Dt = ∂ρw/∂t + u∂ρw/∂x + v∂ρw/∂y + w∂ρw/∂z (non-linear terms) Equation of Continuity: ∂u/∂x + ∂v/∂y + ∂w/∂z = 0
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Modeled currents in southern PS
DOE SPS model
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Equations of motion Momentum equations:
Force/vol Pressure Coriolis Gravity Friction ρDu/Dt = ∂p/∂x + ρ2Ωvsin(φ) ρKx(∂2u/∂x2+∂2u/∂y2+∂2u/∂z2 ) ρDv/Dt = ∂p/∂y - ρ2Ωusin(φ) ρKy(∂2v/∂x2+∂2v/∂y2+∂2v/∂z2 ) ρDw/Ddt = - ∂p/∂z ρg ρKz(∂2w/∂x2+∂2w/∂y2+∂2w/∂z2 ) where Du/Dt = ∂u/∂t + u∂u/∂x + v∂u/∂y + w∂u/∂z Dv/Dt = ∂v/∂t + u∂v/∂x + v∂v/∂y + w∂v/∂z Dw/Dt = ∂w/∂t + u∂w/∂x + v∂w/∂y + w∂w/∂z (non-linear terms) Equation of Continuity: ∂u/∂x + ∂v/∂y + ∂w/∂z = 0
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Scaling momentum equation
Importance of individual terms Re = Reynolds number = L u / n Inertial forces / viscous forces (100m) (0.1 m/s) / 10-6 m2/s) = 107 R0 = Rossby number = u / (f L), f = 2ωsin(φ) Non-linear terms / coriolis term (1 m/s) / ((10-4 s-1)(104 m)) = 1 Rossby radius of deformation ~ u/f = 10 km Ez = Ekman number = Kz/(f H2) Friction term / coriolis term (10-4 m2/s) / ((10-4 s-1)(100m)2) = 10-4 Friction only important along the boundaries of Puget Sound (sea surface, bottom boundary layer)
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SJF cross section Northern shore Southern shore Out In
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