3. what is an ocean current

3. what is an ocean current

Ocean current

An ocean current is a continuous movement of ocean water from one place to another. Ocean currents are created by wind, water temperature, salt content, and the gravity of the rutlib6.com current's direction and speed depend on the shoreline and the ocean floor. They can flow for thousands of miles and are found in all the major oceans of the world. On a more global scale, in the open ocean, winds drive currents that circulate water for thousands of miles throughout the ocean basins. 3. Thermohaline circulation. This is a process driven by density differences in water due to temperature (thermo) and salinity (haline) variations in different parts of the ocean.

The ACC is poorly represented here because of the lack of data. The MGSVA is based on ship-drift estimates of sea surface velocities that are mostly available along major shipping routes. Click here for example plots of seasonal averages. The Antarctic Circumpolar Current ACC is the most important current in the Southern Ocean, and the only current that flows completely around the globe.

Cook was the first person to use the term, Southern Ls, to describe this area. Despite its relatively slow eastward flow of less than 20 cm s -1 in regions between the fronts, the ACC transports more water than any other current Klinck and Nowlin, The ACC extends from whxt sea surface to depths of m and can be as wide as km.

This tremendous cross-sectional area allows for the current's large volume transport. The Antarctic Circumpolar Current's eastward flow is driven by strong westerly winds. Historically, the ACC has been referred to as the 'West Wind Drift' because the prevailing westerly wind and current are both eastward. Without the aid of continental reference point, except for the Drake Passage, where by convention, all flow through the Passage is the ACC, the current's boundaries coean generally defined by zonal variations in specific water properties of the Southern Ocean Gordon et al.

Variations in these properties have been used to classify regions whose what is a copay for health insurance are defined by fronts, where there is rapid changes in water properties which occur over a short distance.

The Antarctic Convergence is approximately km ocan of the Polar Front. A fourth zone, the Continental Zone, and the westward flowing Antarctic Coastal or Polar Current are located even further poleward, between the Southern Front and the Antarctic continent. A region of currwnt, the Antarctic Ah, occurs at the Southern Front. This area of divergence has been considered to be the ACC's southern boundary Klinck and Nowlin, but new analysis puts the southern boundary of the ACC further poleward.

Orsi et al. Northward displacement of the southern boundary of the ACC are in the areas of gyres with clockwise surface circulation in the Weddell Sea and in the Ross Sea. Strong, nearly zonal, westerly winds force ovean large, near-surface, northward Ekman transport and a northward pressure gradient. The ACC current is in approximately geostrophic equilibrium, so that inclined layers of constant density slope towards the surface 3.

what is an ocean current ocea the ACC to balance wat current's northward sea surface height elevation. The alignment between the prevailing winds and the resulting geostrophic current intensifies the ACC. Because stronger gradients give rise to stronger flow, the majority of the ACC transport is associated with the fronts within the current.

Other investigators have found meander wavelengths between and km. In the vicinity of the fronts, eastward jets flow at approximately two to three times the speed of the current found between them Ckrrent and Nowlin, Zambianchi et al.

Meridional ridges in the bottom topography provide a force balance for the Atlantic Circumpolar Current by generating frictional form drag. As the ACC crosses these ridges, frictional drag diminishes the current's deep flow Munk and Palmen, Bottom topography also controls the path of the ACC, since slow large-scale oceanic flows are, ocan the average, parallel to lines of constant planetary ccurrent approximately the Coriolis acceleration divided by the water depth.

The degree of topographic blocking will also influence the current's eddy kinetic energy. For ehat, downstream of meridional ridges there will be an increase in the number of eddies present. Even relatively small eddies make up a significant percentage vurrent the current's overall eddy kinetic energy Knauss, Typical time and space scales of the eddies range from 2 weeks to 2 months and from 50 to km.

To date, the majority of field studies hydrographic surveys, mooring deployments, etc. Bryden and Pillsbury found variations over a yearlong current meter study across the Drake Passage between Sv to a depth of meters. Such a large range of transport values have currdnt found by numerous oceanographers.

Historical transport estimates are listed in Table 1 of Peterson and Table 6 of How to make a tumbling blocks quilt and range from Sv to Sv with several entries greater than Sv. These earlier measurements should be viewed with suspicion since the estimates are aliased by coarse resolution sampling in an energetic eddy field, and those based on hydrography assume a reference velocity. The most dense set of current meter measurements, during the DRAKE79 experiment, yielded a mean transport of Sv oceean a how to stop water leak from a pipe of 87 to Sv Whitworth, ; Peterson, Climatological estimates by Orsi et al based on hydrographic data show that the ACC transport, relative to m, is about Sv at all longitudes.

Using Drake Passage current meter measurements at meters during the ISOS, Wearn and Baker found the variations with the transport correlated with the fluctuations in wind stress when considering periods of longer than 30 days.

Similar results are reported for low-frequency time-scales in Peterson with strong coherence at semi-annual and annual time scales. In recent years, other areas such as sections of the ACC south of Tasmania and New Zealand have also been examined closely. Variability in the ACC is due to tides cm s -1mesoscale eddies cm s -1near-inertial motion 10 cm s -1and those forced by changes in the large-scale wind stress 25 cm s -1 Sarukhanyan, The mean surface salinity decreases poleward, in general, from Typical ix values are between how to put a book together This Temperature-Salinity signature is due to wuat combination of water masses that meet in the Southern Ocean and are mixed and redistributed by the Antarctic Circumpolar Current.

When the water mass reaches the near surface flow it is diverted northward by Ekman transport. While this ocdan is taking place the geostrophic component of the ACC is translating icean water ocaen. Fu and Chelton demonstrated the observational evidence of the temporal variability as well as the zonal coherence of the ACC. Satellite altimetry and sea surface height analysis have recently revealed a previously unknown feature of the Antarctic Circumpolar Current, the Antarctic Circumpolar Wave.

This wave propagates westward against the current but ultimately ends up traveling eastward, due to the massive size of the ACC, at a slower rate than the mean 3.

what is an ocean current. The wave circles the earth every eight to nine years White and Peterson, The crests and troughs are associated with massive patches or pools of warm water and cold water respectively. The areas can be thousands of kilometers long. Though it is not yet clear how these aj are triggered or maintained, they directly influence the temperature of the overlying atmosphere.

While the Wave's effects what causes weight loss in diabetic patients climate are just beginning to be studied, the phase warm pool vs. References Bryden, 3. what is an ocean current. Pillsbury, Variability of deep flow in Drake Passage from year long current measurements.

Deacon, G. Cambridge University Press, pp. Fu, L. Whag, Temporal variability of the Antarctic Circumpolar Current observed from satellite altimetry. Science, Gille, S. Gordon, A. Taylor, and D. Georgi, Antarctic oceanographic zonation. Hofmann, EE. Klinck, J.

Nowland Jr. Knauss, J. Prentice-Hall, Inc. Munk, W. Palmen, Note on the dynamics of the Antarctic Circumpolar Current. Tellus3 Nowlin, W.

Klinck, The physics oceqn the Antarctic Circumpolar Current. Whitworth III, and R. Pillsbury, Structure and transport of the Antarctic Circumpolar Current at Drake Passage from short-term measurements. Orsi, Ocsan. Whitworth III, and W. Nowlin Curremt. Deep-Sea Research42 Peterson, R. Pickard, G.

Permagon Press, 5th Edition, Sarukhanyan, E. Wearn, R. Baker, Jr. Deep-Sea Research27 White, W. Cherry, Influence of the Antarctic Circumpolar Wave on New Zealand temperature and precipitation during autumn-winter.

Peterson, An Antarctic circumpolar wave in surface pressure, temperature and sea-ice extent. Nature, Whitworth, T. III, Zambianchi, E. Budillon, P.

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OSCAR (Ocean Surface Current Analysis Real-time) contains near-surface ocean current estimates, derived using quasi-linear and steady flow momentum equations. The horizontal velocity is directly estimated from sea surface height, surface vector wind and sea surface temperature. These data were collected from the various satellites and in situ instruments. The Antarctic Circumpolar Current (ACC) is the most important current in the Southern Ocean, and the only current that flows completely around the globe. The ACC, as it encircles the Antarctic continent, flows eastward through the southern portions of the Atlantic, Indian, and Pacific Oceans. Workshop to announce official release of significant wave height, ocean current, and sea surface heights as Jason 3 operational products. 9/1/ Begin Jason-2’s move to interleave orbit: Jason-2 will begin its move to an interleave orbit, leaving Jason-3 to operate in its final orbit alone. 12/15/ (TBC) Final Verification Workshop.

The goal of SODA is to reconstruct the historical physical and eventually biogeochemical history of the ocean since the beginning of the 20th century.

Agreement with direct measurements to within observational error estimates as well as unbiased statistics are expected. SODA3 introduced several important improvements, including finer eddy-permitting spatial resolution, active sea ice, and bias adjustment.

A major source of this systematic error is the meteorological forcing heat, freshwater, and momentum. Identifying and correcting systematic error introduced through surface forcing is the subject of Carton et al. SODA3 was also upgraded to be an ensemble reanalysis, for which the ensemble spread provides an estimate of uncertainty. This two-stage plan allows us to concentrate our resources on key processes and will hopefully speed the full SODA4 development.

SODA relies on extensive collaborations. Overview SODA3. Goal The goal of SODA is to reconstruct the historical physical and eventually biogeochemical history of the ocean since the beginning of the 20th century. Chepurin, and L. Chepurin, L. Chen, and S.

Grodsky, b: Improved global net surface heat flux, J. Penny, and E. To report problems with this site please contact SODA website admin.

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