How is Ekman transport calculated?

How is Ekman transport calculated?

At the ocean surface, uE=τwρ√2fKv and vE=−τwρ√2fKv (from Equations 7.9 and \ref7. 6b}, that is, the Ekman velocity is at an angle of 45∘ to the right of the wind direction in the Northern Hemisphere (and to the left of the wind in the Southern Hemisphere) due to the Coriolis force.

What does Ekman transport produce?

Ekman transport piles up surface water in some areas of the ocean and removes water from other areas, producing variations in SSH. This causes the ocean surface to slope gradually. A sloping ocean surface generates water pressure gradients across ocean surfaces.

How do Ekman spirals form?

The Ekman spiral, named after Swedish scientist Vagn Walfrid Ekman (1874-1954) who first theorized it in 1902, is a consequence of the Coriolis effect. As a result, each successively deeper layer of water moves more slowly to the right or left, creating a spiral effect.

When the wind blows southward along the California coast which way does Ekman transport make the surface water move?

Ekman transport moves the surface layer 90o to the right of the wind, meaning the net Ekman transport is in an offshore direction. The water displaced near the coast is replaced by cold, nutrient-rich deeper water that is brought to the surface through upwelling, leading to high productivity (Figure 9.5.

Where Ekman transport is deflected away from the shore?

Coastal upwelling occurs where Ekman transport moves surface waters away from the coast; surface waters are replaced by water that wells up from below.

Where are Ekman layers found?

There are many regions where an Ekman layer is theoretically plausible; they include the bottom of the atmosphere, near the surface of the earth and ocean, the bottom of the ocean, near the sea floor and at the top of the ocean, near the air-water interface.

How does Ekman transport cause upwelling?

Coastal upwelling occurs where Ekman transport moves surface waters away from the coast; surface waters are replaced by water that wells up from below. Where Ekman transport moves surface waters toward the coast, the water piles up and sinks in the process known as downwelling.

Where is the Ekman spiral?

The first documented observations of an oceanic Ekman spiral were made in the Arctic Ocean from a drifting ice flow in 1958. More recent observations include: SCUBA diving observations during a study of upwelling water transport through a kelp forest on the west coast of South Africa in 1978.

What determines the Ekman pumping or Ekman suction )?

Due to the Coriolis effect, surface water moves at a 90° angle to the wind current. If the wind moves in a direction causing the water to be pulled away from the coast then Ekman suction will occur.

Where does Ekman divergence occur?

Coastal Upwelling In the northern hemisphere, Ekman divergence occurs when the wind blows parallel to a coastline on its left. For example, during spring and summer the mean winds along the west coast of North America are southward. Associated with these winds is a net westward Ekman transport.

What are upwellings and Downwellings?

Upwelling is a process in which deep, cold water rises toward the surface. The reverse process, called “downwelling,” also occurs when wind causes surface water to build up along a coastline and the surface water eventually sinks toward the bottom.

What is Ekman spiral in oceanography?

The Ekman spiral is a structure of currents or winds near a horizontal boundary in which the flow direction rotates as one moves away from the boundary. It derives its name from the Swedish oceanographer Vagn Walfrid Ekman.

How are Ekman transports generated?

• Horizontal Ekman transports are generated at a right angle to the surface winds through a balance between wind stress and the Coriolis force. • Where the Ekman transports converge or diverge, vertical motion is generated through the base of the Ekman layer.

How do you calculate Coriolis and Ekman transport?

Coriolis and Ekman Transport. The Coriolis force is given by the Coriolis acceleration times the mass of the object in motion. This is the familiar F = m a. The Coriolis acceleration is proportional to the cross product between the (linear) velocity of the moving object and the angular velocity of the rotating frame of reference.

Why is the Ekman transport to the right of the wind?

In Figure S7.12, with varying zonal (west to east) wind, the Ekman transport is to the right of the wind, and is convergent because the zonal wind varies with latitude. Note that it is not necessary for the Ekman transports to be in opposite directions to have divergence or convergence, just that the transports change. FIGURE S7.12.

Where is the Ekman line directed?

It is directed to the right of the wind in the northern hemisphere and to the left of the wind in the southern hemisphere. There is a force balance between the surface wind stress and the depth- integrated Coriolis force within the Ekman layer.