4 – Oceanography
35
Figure 4.6 Topographic influences and density driven flows. A, Sketch of the 3-D circulation in an island wake (u is the
undisturbed current speed upstream of the island, L is the current speed in the eddy, and W is the width of the island).
(Modified from Wolanski et al. 1988). B, Model-predicted currents near a reef passage showing the formation of a mushroom jet at rising tide. (Modified from Wolanski 2001). C, Internal structure within the jet at flood tide showing the
Bernouilli-effect upwelling of deeper, colder, nutrient-rich oceanic water into the reef passage and the jet-driven landward movement of that passage (u is the water speed in the passage). D, Internal structure at ebb tide showing upwelling
by jet entrainment seaward of the reef passage (u is the water speed in the passage). E, Internal structure of a riverine
plume exiting from the mouth of the river and advecting along the coast. Downwelling occurs at the front and entrainment of coastal waters under the plume. (Modified from Wolanski 2007). F, Density currents generated by muddy water
escaping from Trinity Bay off Cairns, cascading down to deeper water and being entrained by the prevailing currents on
the shelf. (Modified from Brinkman et al. 2004).
L
I s la n d
Eddy
Eddy
Upwelling
Downwelling
u
(A)
(B)
(C)
(D)
(F)
(E)
35
Figure 4.6 Topographic influences and density driven flows. A, Sketch of the 3-D circulation in an island wake (u is the
undisturbed current speed upstream of the island, L is the current speed in the eddy, and W is the width of the island).
(Modified from Wolanski et al. 1988). B, Model-predicted currents near a reef passage showing the formation of a mushroom jet at rising tide. (Modified from Wolanski 2001). C, Internal structure within the jet at flood tide showing the
Bernouilli-effect upwelling of deeper, colder, nutrient-rich oceanic water into the reef passage and the jet-driven landward movement of that passage (u is the water speed in the passage). D, Internal structure at ebb tide showing upwelling
by jet entrainment seaward of the reef passage (u is the water speed in the passage). E, Internal structure of a riverine
plume exiting from the mouth of the river and advecting along the coast. Downwelling occurs at the front and entrainment of coastal waters under the plume. (Modified from Wolanski 2007). F, Density currents generated by muddy water
escaping from Trinity Bay off Cairns, cascading down to deeper water and being entrained by the prevailing currents on
the shelf. (Modified from Brinkman et al. 2004).
L
I s la n d
Eddy
Eddy
Upwelling
Downwelling
u
(A)
(B)
(C)
(D)
(F)
(E)