Frictional estuarine circulation in Juan de Fuca Strait, with implications for secondary circulation

Michael Ott and Chris Garrett

J. Geophys. Res., 103, 15,657-15,666, 1998.

Estuarine flow in Juan de Fuca Strait is highly seasonal in nature; July's peak in Fraser River discharge coincides with an appreciable along-channel sea surface slope. An upper layer momentum balance requires the vertical eddy viscosity A_v to be on the order of 0.03 m^2/s, larger than implied by conventional empirical formulae and used in current models. The mixing in an estuarine channel and large vertical eddy viscosity should lead to significant cross-channel flows. This secondary circulation, which may be due to internal Ekman layers and intrusions of water mixed at the sloping sides of the strait, is much less understood than the basic along-channel estuarine exchange. Unfortunately, historical current meter data in Juan de Fuca Strait are of insufficient spatial resolution to show the predicted patterns.

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