Ekman Spiral Effect & Ekman Transport | Ekman Layer
Ekman Spiral
The Ekman spiral is a graphical representation of the earth’s wind patterns. It was developed by Swedish meteorologist, Vagn Walfrid Ekman in 1904.
The name Ekman spiral derives from the fact that it rises at an angle of 17.6 degrees relative to the ground plane (the imaginary surface on which all points are level). This angle is called the Ekman angle after the Swedish scientist Vagn Walfrid Ekman who did extensive work on ocean surface currents. The helix is formed by rotating an imaginary line through the center of a circle at this angle around the center of the circle.
The Ekman spiral is made up of three parts:
- An equator line that represents the surface winds with their direction and speed; this corresponds to latitude on Earth’s surface
- A set of concentric circles that represent constant pressure levels at various altitudes above sea level (MSL) or ground level (AGL), also known as geopotential height; these correspond to longitude on earth’s surface.
- A set of lines connecting points where the wind changes from one direction to another
The spiral is created by drawing a series of concentric circles on paper and then plotting points where the lines intersect with each other.
A point’s position on the spiral indicates its velocity relative to another point, which can be determined by measuring the angle between two adjacent lines
Ekman Spiral Effect & Coriolis effect
Vagn Walfrid Ekman (1874-1954) developed the Ekman Spiral in 1902 to explain the Coriolis effect. As surface water molecules are pulled by the force of the wind, they drag deeper layers of water molecules underneath them. Every layer of water molecules is driven by friction from the shallower layer to the deeper layer, and each deeper layer moves more slowly than the layer above it until the movement ends at a depth of about 100 meters (330 feet).
The Coriolis impact, like the surface water, deflects deeper water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. As a result, as the water depth rises, it travels more slowly to the right or left, causing a spiral impact. Since deeper layers of water move more slowly than shallower layers, they “twist around” and flow in the opposite direction of the surface current.
The typical Ekman spiral has been observed under sea ice, but observations in the open ocean remain rare. This is due to the fact that turbulent mixing in the ocean’s surface layer has a heavy diurnal cycle, as well as the fact that surface waves can destabilize the Ekman spiral.
Ekman spirals can be seen in the atmosphere as well. In the Northern Hemisphere, surface winds appear to blow to the left of winds aloft.
Ekman Transport
The Ekman transport is a mathematical model that describes how wind-driven currents move heat from one location to another.
Ekman transport is the net motion of a fluid produced by a combination of Coriolis and turbulent drag forces. The wind blowing north in the northern hemisphere causes surface tension, and an Ekman spiral is found below it in the water column.
Ekman Spiral and Ekman Transport
What is the difference between the Ekman spiral and Ekman transport?
The Ekman spiral is a graphical representation of the magnitude and direction of ocean currents. It is created by drawing circles on a map, with each circle’s size proportional to the speed of its corresponding current.
The Ekman transport on the other hand describes how water masses are transported from one region to another in an ocean basin.
The Ekman spiral is a model of the atmosphere that predicts how air moves from high to low pressure whereas the Ekman transport is an equation that describes the rate at which heat or momentum are transferred between two layers of fluid with different temperatures.
The Ekman spiral is a model that predicts how ocean currents move in the Northern Hemisphere. It was created by Swedish meteorologist Vagn Walfrid Ekman and can be used to determine wind speed and direction, as well as the strength of water currents.
The Ekman transport equation is used to calculate how much heat energy is transported from one location to another by ocean currents
Ekman Layer
The Ekman layer is the layer in a fluid where there is a force balance between pressure gradient force, Coriolis force and turbulent drag
The Ekman layer is a thin, stable layer reated by the wind and waves as they mix up the top few millimeters of water. This layer has a high salt content because it comes from seawater below and evaporated spray from above.
Ekman layers occur both in the atmosphere and in the ocean.
The Ekman layer can be seen in satellite images when there are no clouds or other particles to obscure its visibility