Temporal Variability

Tidal SubtidalWind and Atmospheric Pressure

FortnightlyM2 and S2

MonthlyM2 and N2

Seasonal (River Discharge)

Estuarine Variability

Tidal SubtidalWind and Atmospheric Pressure

FortnightlyM2 and S2

MonthlyM2 and N2

Seasonal (River Discharge)

Tidal Straining

Animation of Shear Instability

Example of Tidal interaction with density gradient

Chilean Inland Sea

Pitipalena Estuary

12CTDTimeSeries

Example of Tidal Straining

Maximum stratification at the end of ebb

Dynamically, tidal motion modifies the mean value of bottom friction.where ub is the instantaneous bottom velocityBottom friction depends then on the tidal current amplitude.

Another dynamical implication of tidal flows is the generation of a mean non-linear term:Tidal stresses tend to operate with the barotropic pressure gradient.

Estuarine Variability

Tidal SubtidalWind and Atmospheric Pressure

FortnightlyM2 and S2

MonthlyM2 and N2

Seasonal (River Discharge)

Subtidal Variability

Produced by direct forcing on estuary (local forcing) or on the coastal ocean, which in turn influences estuary (remote forcing - coastal waves)Wind-produced mixing

The energy per unit area per unit time or power per unit area generated by the wind to mix the water column is proportional to W3

At a height of 10 m, the power per unit area generated by the wind stress is:The wind power at the air water interface is only 0.1 % of the wind power at a height of 10 m.

Forzamiento por vientoprofundidadDepende de la estratificacin de la columna de agua

Ejemplo Estrecho de Meninea en Canal Moraleda

(combinando forzamiento por marea, viento, presin)

Ejemplo Meninea (combinando forzamiento por marea, viento, presin)Tambin produce oscilaciones en la picnoclina == resonancia

Wind-Induced Surface SlopeCan 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.Wind will pile up water in the direction toward which it blows.

Slopes produced by different winds in Chesapeake Bay

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:

Forzamiento por Gradientes de Presin Atmosfrica

Another mechanism that may cause subtidal variability in estuaries comes from atmospheric or barometric pressure.

Estuarine Variability

Tidal SubtidalWind and Atmospheric Pressure

FortnightlyM2 and S2

MonthlyM2 and N2

Seasonal (River Discharge)

Tides in Panama City

(JGR, 1982, 87(C10), 7985)

Thomson et al. (2007, JGR, 112, C09022)

Thomson et al. (2007, JGR, 112, C09022)

Thomson et al. (2007, JGR, 112, C09022)

DepthMean orResidualFlowMean orResidualSalinity(Density)Increasing salinitySpringNeapOceanCan you see this modulation from the analytical solution?

Estuarine Variability

Tidal SubtidalWind and Atmospheric Pressure

FortnightlyM2 and S2

MonthlyM2 and N2

Seasonal (River Discharge)

(JGR, 1982, 87(C10), 7985)

NCNCNC

Axial Distributionsof SalinitySpring 1999Fall 1999HMHMHM