This upper thermohaline circulation is of minor importance compared to the wind driven circulation. The surface layer of the ocean is directly driven by the surface wind. It is also called thermohaline circulation because is. These two components act simultaneously to drive the moc, the movement of seawater across basins and depths. The adjective thermohaline derives from thermoreferring to temperature and haline referring to salt content, factors which together determine the density of sea water. The interaction between ocean circulation and climate change has been an active research frontier in earth sciences in recent years. Thus the vertical thermal structure depends on latitudinal surface temperature variations. They, by necessity, assumed a steady atmosphere that exerted wind stress on the ocean surface, and ignored the effects from heat and water flux.
In reality is not independent on the wind circulation, but a representation of it can be obtained considering buoyancy effects alone. This is not the first study to consider some aspect of ocean circulation in thermohaline coordinates. The thermohaline circulation is not the only one leading to descent of sea water into the deep ocean. These deepocean currents are driven by differences in the waters density, which is controlled by temperature thermo and salinity haline. Understanding the winddriven ocean circulation on a tidally. The general idea is that near the equator, the ocean receives excess radiative heating and thus heats up the ocean. Giant patterns of meridional overturning circulation are set up that cross the equator and connect the hemispheres together. Southern ocean and its complex processes highlight the intertwined nature of the different components. This is the first advanced textbook to discuss both winddriven and thermohalinedriven processes two important aspects of largescale ocean circulation. Because the ocean density is a function of temperature thermo and salinity haline, this circulation is referred to as the themohaline circulation and indicates a driving mechanism.
Conceptions of thermohaline circulation dense deep water, formed at high latitudes, has long been thought as the driving force for the thermohaline circulation in the oceans. Ocean circulation winddriven and thermohaline processes r. It plays an important role in supplying heat to the polar regions, and thus in sea ice regulation. On the driving processes of the atlantic meridional. The conveyor belt begins on the surface of the ocean near the pole in the north atlantic.
P e caused by atmospheric exchange are crucial for driving largescale flows. Nov 10, 2012 ocean circulation what drives the ocean circulation. In these regions the water is not forced down vertically but along constant density surfaces. Surface heat and freshwater fluxes create global density gradients that drive the thermohaline circulation part of largescale ocean circulation. Rui xin huang ocean circulation winddriven and thermohaline. An efficient thermohaline circulation seems to be restricted to the upper layers in tropical and subtropical regions. However, ocean currents also flow thousands of meters below the surface. Ocean circulation winddriven and thermohaline processes. As the name suggests, the wind driven circulation is. The deep flow in the southern, indian, and pacific oceans.
Different from the wind driven ocean circulation, which is generally in the upper 12km of the ocean, the amoc extends to the very deep ocean. It is that part of the ocean circulation which is driven by density differences as opposed to wind and tides. As opposed to wind driven currents and tides the latter are due to the gravity of moon and sun, the thermohaline circulation often abbreviated as thc is that part of the ocean circulation which is driven by fluxes of heat and freshwater across the sea surface and subsequent interior mixing of heat. Four simple and inexpensive aquariascale models are used to illustrate the major ocean circulation processes and the nature of convection. Ocean circulation, and its related geophysical fluid dynamical principles, are now taught at graduate level in many earth and atmospheric science departments. The effects of thermohaline circulation on winddriven. Conceptual models for the thermohaline circulation 522006 9.
In a wind driven world ocean circulation, the most prominent feature is no doubt the existence of a western boundary current, just like kuroshio in the pacific and gulf stream in the atlantic. Ocean circulation wind driven and thermohaline processes r. It was question as well weather or not these two processes happen when the wind pushes along the water or else if they are convection currents due to heating and cooling processes. The adjective thermohaline derives from thermo referring to temperature and haline referring to salt content, factors which together determine the density of sea water. The three main patterns of ocean circulation are gyres, upwelling, and thermohaline circulation. Thermohaline ocean circulation potsdam institute for climate.
It provides a concise introduction to the dynamics and thermodynamics of oceanic general circulation. Speer 1993 relates airsea heat and salt fluxes to a transformation rate effectively advection in thermohaline coordinates. Ocean dynamics and the inner edge of the habitable zone for. We assume that both thermohaline and wind driven forcing are important to the arctic ocean s circulation, and we agree with treshnikov and baranovs 1972 conclusion that the role of individual factors in the circulation cannot be easily evalu ated because observed temperature and salinity distributions.
Thermohaline circulation thc is a part of the largescale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. Winddriven circulation, which is strongest in the surface layer of the ocean, is the more vigorous of the two and is configured as large gyres that dominate an ocean region. The ocean circulation can be reasonably well separated into portions that result from wind and from thermohaline forcing. The difference between thermohaline and wind driven circulation was distinguished in the 19thcentury, during an argument regarding ocean currents. Thermohaline circulation deep, driven by fluxes of heat and freshwater across the sea surface. This is the first advanced textbook to discuss both winddriven and thermohaline driven processes two important aspects of largescale ocean circulation.
The best understanding of circulation concerns the wind driven ocean circulation, where notable developments were made by ekman 1905, 1923, sverdrup 1947, and stommel 1948. Pressure, temperature, salinity, and some thermohaline dynamics. Two types of ocean circulation define two circulation types. Pdf models of winddriven and thermohaline ocean circulation. Winddriven circulation an overview sciencedirect topics.
Sea water density depends on temperature and salinity, hence the name thermohaline. Ocean circulation and climate the thermohaline circulation. Driven by winds, the surface currents form the main subtropical. For instance, if earths global ocean circulation were. Buoyancy fluxes are the net effect of heat exchange and the freshwater exchange with the overlying atmosphere. Changes in the thermohaline circulation are thought to have significant impacts on earths energy budget. Unlike the faster winddriven circulation, which is con. Global ocean circulation can be divided into two major components. As opposed to winddriven currents and tides which are due to the gravity of moon and sun, the thermohaline circulation fig. Upwelling ecosystems are among the most productive in the world ocean, contributing 10% of the worlds primary productivity and 20% of the worlds fisheries catch.
Thermohaline circulation an overview sciencedirect topics. Environmental scientists study ocean circulation because, along with patterns of air movement in the atmosphere, the movement of water through the oceans helps determine weather and climate conditions for different regions of the world. Thermohaline circulation drives a globalscale system of currents called the global conveyor belt. Winddriven and thermohaline processes the interaction between ocean circulation and climate change has been an. The present discussion has shown that the winddriven circulation and the thermohaline circulation are major components of ocean circulation, which are ultimately driven by the surface wind stress and buoyancy fluxes. It is estimated that any given cubic meter of water takes about. This is the first advanced textbook to discuss both wind driven and thermohaline driven processes two important aspects of largescale ocean circulation. When depth to the picolene is shallow that means cold bottom h20 comes to the surface this is called upwelling. Chapter 10 the winddriven circulation in chapter 9 we saw that the ocean comprises a warm, salty, strati.
Winds drive ocean currents in the upper 100 meters of the oceans surface. Ocean circulation, winddriven and thermohaline processes the chinese eddition, including corrections for typos will be published april, 2012, by high education press of china book cover pdf errata last updated on july 12012 pdf ocean garden this is a garden where i collect my most recent thought about physics of the ocean. The circulation of the ocean is usually divided into two parts, a winddriven circulation that dominates in the upper few hundred meters, and a densitydriven circulation that dominates below. The present discussion has shown that the wind driven circulation and the thermohaline circulation are major components of ocean circulation, which are ultimately driven by the surface wind stress and buoyancy fluxes.
Huang the circulation of the oceans is a fundamental process in the movement of energy and materials around the planet. Two circulation regimes of the winddriven arctic ocean. These, however, are superimposed on the much more sluggish circulation driven by horizontal differences in temperature and salinitynamely, thermohaline circulation. The winddriven ocean circulation that results contains subtropical gyres. The meridional overturning circulation is associated to the abyssal circulation in the ocean. When the density gradients cause the motion in this manner and are not themselves a consequence of the internal adjustment of fluid masses to geostrophic equilibrium in e. As opposed to winddriven currents and tides the latter are due to the gravity of moon and sun, the thermohaline circulation often abbreviated as thc is that part of the ocean circulation which is driven by fluxes of heat and freshwater across the sea surface and subsequent interior mixing of heat. In a winddriven world ocean circulation, the most prominent feature is no doubt the existence of a western boundary current, just like kuroshio in the pacific and gulf stream in the atlantic. Thermohaline circulation fact sheet by stefan rahmstorf. The latter is called the thermohaline circulation because of the role of heating, cooling, freshening, and salini. Chapter 11 the thermohaline circulation of the ocean. Thermohaline circulation the reader wiki, reader view of. Four simple and inexpensive aquariascale models are used to illustrate the major oceancirculation processes and the nature of convection. Water mass and tracer analysis of the deep flow in the atlantic ocean.
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