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.
Where does Ekman transport occur?
Ekman suction occurs both along coastlines and in the open ocean, but also occurs along the equator . Along the Pacific coastline of California, Central America, and Peru, as well as along the Atlantic coastline of Africa there are areas of upwelling due to Ekman suction, as the currents move equatorwards.
Where do Ekman spirals occur?
Ekman spirals are also found in the atmosphere . Surface winds in the Northern Hemisphere tend to blow to the left of winds aloft.
What happens when Ekman transports converge?
Ekman transport convergence and divergence in the Northern Hemisphere due to variations in a zonal (eastward) wind. Ekman transport is southward, to the right of the wind. Divergent transport causes downwelling, denoted by circles with a cross. Convergent transport causes upwelling , denoted by circles with a dot.
How is Ekman transport determined?
Given a measure surface wind stress you can compute the vertical Velocity at the Base of the Ekman Layer. Downward Velocity = Ekman Pumping, Upward Velocity = Ekman Suction Given a measure surface wind stress you can compute the horizontal components of the total mass transport integrated over the the Ekman Layer.
What causes Ekman divergence?
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.
How deep do Ekman spirals go?
The speed and direction of the moving water changes with depth. Ocean water at the surface moves at an angle to the wind, and the water under the surface water turns a bit more, and the water below that turns even more. This makes a spiral of moving water 100 to 150 meters (330 to 500 ft) deep called an Ekman spiral.
What is the difference between Ekman transport and geostrophic flow?
The Ekman transport piles up water in the center of the gyre, making the water level higher in the gyre center than on the edges of the gyres. ... This results in a clockwise current around the central “hill” called geostrophic flow , which moves in the same direction as the rotating gyre.
How does Ekman cause downwelling?
As wind blows along a coastline, Ekman transport moves the surface layer in a direction 90 o to the wind . ... In any coastal upwelling location, if the winds reverse, surface water moves towards the shore and downwelling is the result.
The Ekman spiral is a consequence of the coriolis effect. When the surface water moves by the wind, they drag the deeper layers with them . ... The net water transport is perpendicular (90°) to the initial wind direction and this is the effective direction of the current flow.
How deep is the Ekman layer?
Ekman layer, a vertical region of the ocean affected by the movement of wind-driven surface waters. This layer, named for the Swedish oceanographer V. Walfrid Ekman, extends to a depth of about 100 metres (about 300 feet) .
What causes the Coriolis effect?
Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere . This deflection is called the Coriolis effect.
When you have ocean current divergence What will it cause?
Divergence of currents will create an upwelling phase (interior waters reach the surface) and convergence a downwelling phase (surface waters sink in the interior ocean), linking surface and interior waters . The slow and deep circulation is largely driven by water density, and thus its temperature and salinity.
What is the difference between eastern and western boundary currents?
To move the same volume of water through each side, western boundary currents are faster, deeper, and narrower than eastern boundary currents . ... In the same way, western boundary currents are not only faster, but also deeper than eastern boundary currents, as they move the same volume through a narrower space.
What is Ekman transport quizlet?
Ekman transport. The sum of water layer movement due to the Ekman spiral pattern . Theoretical Ekman transport in the Northern Hemisphere is 90 to the right of the wind direction.
What is a Geostrophic gyre?
The horizontal movement of surface water arising from a balance between the pressure gradient force and the Coriolis force is known as geostrophic flow. As noted earlier, viewed from above, geostrophic flow in a subtropical gyre is clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.
