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- Ekman_spiral abstract "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. The deflection of surface currents was first noticed by the Norwegian oceanographer Fridtjof Nansen during the Fram expedition (1893–1896) and the effect was first physically explained by Vagn Walfrid Ekman.The effect is a consequence of the Coriolis effect which subjects moving objects to a force to the right of their direction of motion in the northern hemisphere (and to the left in the Southern Hemisphere). Thus, when a persistent wind blows over an extended area of the ocean surface in the northern hemisphere, it causes a surface current which accelerates in that direction, which then experiences a Coriolis force and acceleration to the right of the wind: the current will turn gradually to the right as it gains speed. As the flow is now somewhat right of the wind, the Coriolis force perpendicular to the flow's motion is now partly directed against the wind. Eventually, the current will reach a top speed when the force of the wind, of the Coriolis effect, and the resistant drag of the subsurface water balance, and the current will flow at a constant speed and direction as long as the wind persists. This surface current drags on the water layer below it, applying a force in its own direction of motion to that layer, repeating the process whereby that layer eventually becomes a steady current even further to the right of the wind, and so on for deeper layers of water, resulting in a continuous rotation (or spiraling) of current direction with changing depth. As depth increases, the force transmitted from the driving wind declines and thus the speed of the resultant steady current decreases, hence the tapered spiral representation in the accompanying diagram. The depth to which the Ekman spiral penetrates is determined by how far turbulent mixing can penetrate over the course of a pendulum day.The diagram above attempts to show the forces associated with the Ekman spiral as applied to the Northern hemisphere. The force from above is in red (beginning with the wind blowing over the water surface), the Coriolis force (which is shown at right angles to the force from above when it should in fact be at right angles to the actual water flow) is in dark yellow, and the net resultant water movement is in pink, which then becomes the force from above for the layer below it, accounting for the gradual clockwise spiral motion as you move down.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 The 1980 Mixed Layer Experiment Within the Sargasso Sea during the 1982 Long Term Upper Ocean Study Within the California Current during the 1993 Eastern Boundary Current experiment Within the Drake Passage region of the Southern Ocean Common to several of these observations spirals were found to be 'compressed', displaying larger estimates of eddy viscosity when considering the rate of rotation with depth than the eddy viscosity derived from considering the rate of decay of speed. Though in Drake Passage the 'compression', or spiral flattening effect disappeared with a longer time series that permitted a more careful treatment of the effect of geostrophic shear.The classic Ekman spiral has been observed under sea ice, but observations remain rare in open-ocean conditions. This is due both to the fact that the turbulent mixing in the surface layer of the ocean has a strong diurnal cycle and to the fact that surface waves can destabilize the Ekman spiral. Ekman spirals are also found in the atmosphere. Surface winds in the Northern Hemisphere tend to blow to the left of winds aloft.".
- Ekman_spiral thumbnail Ekman_spirale.svg?width=300.
- Ekman_spiral wikiPageExternalLink search?id=ekman-spiral1.
- Ekman_spiral wikiPageID "1649731".
- Ekman_spiral wikiPageLength "8065".
- Ekman_spiral wikiPageOutDegree "16".
- Ekman_spiral wikiPageRevisionID "678523764".
- Ekman_spiral wikiPageWikiLink Category:Fluid_dynamics.
- Ekman_spiral wikiPageWikiLink Category:Oceanography.
- Ekman_spiral wikiPageWikiLink Coriolis_effect.
- Ekman_spiral wikiPageWikiLink Diurnal_cycle.
- Ekman_spiral wikiPageWikiLink Ekman_layer.
- Ekman_spiral wikiPageWikiLink Ekman_transport.
- Ekman_spiral wikiPageWikiLink Fridtjof_Nansen.
- Ekman_spiral wikiPageWikiLink Nansens_Fram_expedition.
- Ekman_spiral wikiPageWikiLink Oceanography.
- Ekman_spiral wikiPageWikiLink Secondary_flow.
- Ekman_spiral wikiPageWikiLink Surface_layer.
- Ekman_spiral wikiPageWikiLink Sweden.
- Ekman_spiral wikiPageWikiLink Upwelling.
- Ekman_spiral wikiPageWikiLink Vagn_Walfrid_Ekman.
- Ekman_spiral wikiPageWikiLink File:Ekman_spirale.svg.
- Ekman_spiral wikiPageWikiLinkText "Ekman Effect".
- Ekman_spiral wikiPageWikiLinkText "Ekman Spiral".
- Ekman_spiral wikiPageWikiLinkText "Ekman pumping".
- Ekman_spiral wikiPageWikiLinkText "Ekman spiral".
- Ekman_spiral wikiPageWikiLinkText "Ekman theory".
- Ekman_spiral hasPhotoCollection Ekman_spiral.
- Ekman_spiral wikiPageUsesTemplate Template:Commons.
- Ekman_spiral wikiPageUsesTemplate Template:Physical_oceanography.
- Ekman_spiral wikiPageUsesTemplate Template:Reflist.
- Ekman_spiral subject Category:Fluid_dynamics.
- Ekman_spiral subject Category:Oceanography.
- Ekman_spiral hypernym Structure.
- Ekman_spiral type Building.
- Ekman_spiral type Dynamic.
- Ekman_spiral type Mechanic.
- Ekman_spiral type Science.
- Ekman_spiral comment "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.".
- Ekman_spiral label "Ekman spiral".
- Ekman_spiral sameAs Espiral_dEkman.
- Ekman_spiral sameAs Ekman_spiral.
- Ekman_spiral sameAs Korkenzieherströmung.
- Ekman_spiral sameAs Espiral_de_Ekman.
- Ekman_spiral sameAs Ekmani_spiraal.
- Ekman_spiral sameAs Ekmanin_spiraali.
- Ekman_spiral sameAs Spirale_dEkman.
- Ekman_spiral sameAs Spirale_di_Ekman.
- Ekman_spiral sameAs Ekmanspiraal.
- Ekman_spiral sameAs Ekmanspiral.
- Ekman_spiral sameAs Ekmanspiral.
- Ekman_spiral sameAs Spirala_Ekmana.
- Ekman_spiral sameAs Espiral_de_Ekman.
- Ekman_spiral sameAs m.05klzm.
- Ekman_spiral sameAs Экмановская_спираль.
- Ekman_spiral sameAs Ekmanspiral.
- Ekman_spiral sameAs Спіраль_Екмана.
- Ekman_spiral sameAs Xoắn_ốc_Ekman.
- Ekman_spiral sameAs Q607421.
- Ekman_spiral sameAs Q607421.
- Ekman_spiral sameAs 埃克曼螺旋.
- Ekman_spiral wasDerivedFrom Ekman_spiral?oldid=678523764.
- Ekman_spiral depiction Ekman_spirale.svg.
- Ekman_spiral isPrimaryTopicOf Ekman_spiral.