How does wind affect upwelling?
Conditions are optimal for upwelling along the coast when winds blow along the shore. Winds blowing across the ocean surface push water away. Water then rises up from beneath the surface to replace the water that was pushed away. This process is known as “upwelling.”
What causes coastal upwelling?
Coastal upwelling is the process by which strong winds blow down the coasts of continents and, in conjunction with the earth’s rotation, cause the surface waters to be pushed offshore. Water from the ocean depths is then pulled up – or upwelled – to the surface to take its place.
What factors affect upwelling?
The combination of weak winds and deeper water limits upwelling. The reduction in nutrient-rich water leads to a lower fish population in the area, and therefore to a smaller fish crop. Upwelling affects the movement of animal life in the area.
What are two specific regions where significant upwelling occurs?
Most major upwelling regions are found along the west coasts of continents, such as off California, Peru, Namibia and South Africa. Large-scale upwelling off the west coast of Australia is suppressed due to the poleward-flowing Leeuwin Current.
What is an upwell?
intransitive verb. : to well up specifically : to move or flow upward.
What causes the Ekman spiral?
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. When surface water molecules move by the force of the wind, they, in turn, drag deeper layers of water molecules below them.
What is the difference between the Ekman spiral and Ekman transport?
The impact of the Ekman Spiral is enhanced where geographic features create barriers to the movement of water. Ekman transport is the net motion of a fluid (seawater) as the result of a balance between the Coriolis effect and turbulent drag forces (within surface waters and geographic features (shoreline and seabed).
How does the Ekman spiral work?
An Ekman spiral (A) is a rotating column of water that forms when water moves at an angle to the wind direction due to the Coriolis Effect. The net effect of the rotating water (B) is movement at right angle to the wind direction. The water turns to the left instead of right in the Southern Hemisphere.
What are the two main forces responsible for the existence of the Ekman spiral?
Ekman spiral rotating column of water formed as ocean surface currents are deflected by the Coriolis effect, wind, and friction forces.
What is the primary mechanism for the Ekman spiral effect?
1 The Ekman spiral, shown for the Northern Hemisphere. Wind blowing over the water (blue arrow) creates a surface current 45o offset from the wind. Each successive layer of water is moved and deflected by the layer above, creating a spiraling pattern of water movement that diminishes with depth.
What causes the Ekman transport?
Ekman transport occurs when ocean surface waters are influenced by the friction force acting on them via the wind. As the wind blows it casts a friction force on the ocean surface that drags the upper 10-100m of the water column with it.
How deep is the Ekman layer?
about 100 metres
What is the Ekman boundary layer?
The Ekman layer is defined as the surface boundary layer in which the frictional force is balanced by Coriolis force.
Where can Ekman layers be found?
Ekman layers occur both in the atmosphere and in the ocean. There are two types of Ekman layers. The first type occurs at the surface of the ocean and is forced by surface winds, which act as a drag on the surface of the ocean.
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 describes a theoretical direction of Ekman transport in the Southern Hemisphere?
In the Southern Hemisphere, the net water movement is 90 degrees to the left of the wind direction. This net transport of water due to coupling between wind and surface waters is known as Ekman transport.
What happens at ocean surface divergences?
In (a) there is a divergence at the surface which depresses the surface of the ocean and raises water from beneath the thermocline towards the surface (upwelling). In (b) the surface waters converge which pushes the sea surface upwards and depresses the thermocline (downwelling).
How does sea surface circulation occur?
Surface currents in the ocean are driven by global wind systems that are fueled by energy from the sun. Patterns of surface currents are determined by wind direction, Coriolis forces from the Earth’s rotation, and the position of landforms that interact with the currents.
What are the two types of ocean currents?
There are two type of Ocean Currents:
- Surface Currents–Surface Circulation.
- Deep Water Currents–Thermohaline Circulation.
- Primary Forces–start the water moving.
- The primary forces are:
- Secondary Forces–influence where the currents flow.
- Solar heating cause water to expand.
What is it called when surface currents meet and converge?
Atmospheric circulation and the Coriolis effect create global wind patterns including the trade winds and westerlies. These prevailing winds, known as the trade winds, meet at the Intertropical Convergence Zone (also called the doldrums) between 5 degrees North and 5 degrees South latitude, where the winds are calm.
What is the most important cause of surface currents?
Currents are caused by winds, gravity, and variations in water density in different parts of the ocean. Wind is the most important cause of surface currents. When strong, sustained winds blow across the sea, friction drags a thin layer of water into motion.
What 3 things affect surface currents?
Surface currents are created by three things: global wind patterns, the rotation of the Earth, and the shape of the ocean basins. Surface currents are extremely important because they distribute heat around the planet and are a major factor influencing climate around the globe.