Thermohaline ocean circulation potsdam institute for climate. 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. Unlike the faster winddriven circulation, which is con. Global ocean circulation can be divided into two major components. Two circulation regimes of the winddriven arctic ocean. Winddriven and thermohaline processes the interaction between ocean circulation and climate change has been an. Sea water density depends on temperature and salinity, hence the name thermohaline. The difference between thermohaline and wind driven circulation was distinguished in the 19thcentury, during an argument regarding ocean currents.
An efficient thermohaline circulation seems to be restricted to the upper layers in tropical and subtropical regions. Winddriven circulation an overview sciencedirect topics. However, ocean currents also flow thousands of meters below the surface. Understanding the winddriven ocean circulation on a tidally. When depth to the picolene is shallow that means cold bottom h20 comes to the surface this is called upwelling. Winds drive ocean currents in the upper 100 meters of the oceans surface. The adjective thermohaline derives from thermo referring to temperature and haline referring to salt content, factors which together determine the density of sea water. 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. Chapter 11 the thermohaline circulation of the ocean.
The effects of thermohaline circulation on winddriven. Buoyancy fluxes are the net effect of heat exchange and the freshwater exchange with the overlying atmosphere. Giant patterns of meridional overturning circulation are set up that cross the equator and connect the hemispheres together. 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. Pressure, temperature, salinity, and some thermohaline dynamics. Huang the circulation of the oceans is a fundamental process in the movement of energy and materials around the planet. Four simple and inexpensive aquariascale models are used to illustrate the major ocean circulation processes and the nature of convection. As opposed to winddriven currents and tides which are due to the gravity of moon and sun, the thermohaline circulation fig. The dynamic influence of thermohaline circulation on wind driven circulation in the south china sea scs is studied using a simple reduced gravity model, in which the upwelling driven by mixing in the abyssal ocean is treated in terms of an upward pumping distributed at the base of the upper layer. This is the first advanced textbook to discuss both winddriven and thermohalinedriven processes two important aspects of largescale ocean circulation. It provides a concise introduction to the dynamics and thermodynamics of oceanic general circulation. Thermohaline circulation the reader wiki, reader view of.
Changes in the thermohaline circulation are thought to have significant impacts on earths energy budget. Thermohaline circulation deep, driven by fluxes of heat and freshwater across the sea surface. 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. 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. Nov 10, 2012 ocean circulation what drives the ocean circulation. The winddriven ocean circulation that results contains subtropical gyres. 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. Pdf models of winddriven and thermohaline ocean circulation. Conceptual models for the thermohaline circulation 522006 9. P e caused by atmospheric exchange are crucial for driving largescale flows. Surface heat and freshwater fluxes create global density gradients that drive the thermohaline circulation part of largescale ocean circulation. Four simple and inexpensive aquariascale models are used to illustrate the major oceancirculation processes and the nature of convection. Thermohaline circulation drives a globalscale system of currents called the global conveyor belt.
The interaction between ocean circulation and climate change has been an active research frontier in earth sciences in recent years. Driven by winds, the surface currents form the main subtropical. The deep flow in the southern, indian, and pacific oceans. The adjective thermohaline derives from thermoreferring to temperature and haline referring to salt content, factors which together determine the density of sea water. The surface layer of the ocean is directly driven by the surface wind. Thermohaline circulation fact sheet by stefan rahmstorf. 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. For instance, if earths global ocean circulation were. Thus the vertical thermal structure depends on latitudinal surface temperature variations. 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. On the driving processes of the atlantic meridional.
It is estimated that any given cubic meter of water takes about. 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. Speer 1993 relates airsea heat and salt fluxes to a transformation rate effectively advection in thermohaline coordinates. Rui xin huang ocean circulation winddriven and thermohaline. Southern ocean and its complex processes highlight the intertwined nature of the different components. This is the first advanced textbook to discuss both wind driven and thermohaline driven processes two important aspects of largescale ocean circulation. Thermohaline circulation an overview sciencedirect topics. 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. Ocean circulation and climate the thermohaline circulation. 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.
The general idea is that near the equator, the ocean receives excess radiative heating and thus heats up the ocean. 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. Ocean circulation winddriven and thermohaline processes r. Ocean dynamics and the inner edge of the habitable zone for. Ocean circulation winddriven and thermohaline processes.
This upper thermohaline circulation is of minor importance compared to the wind driven circulation. 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. This is not the first study to consider some aspect of ocean circulation in thermohaline coordinates. Two types of ocean circulation define two circulation types. They, by necessity, assumed a steady atmosphere that exerted wind stress on the ocean surface, and ignored the effects from heat and water flux. 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 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.
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. 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. It plays an important role in supplying heat to the polar regions, and thus in sea ice regulation. As the name suggests, the wind driven circulation is. The ocean circulation can be reasonably well separated into portions that result from wind and from thermohaline forcing. Water mass and tracer analysis of the deep flow in the atlantic ocean. It is that part of the ocean circulation which is driven by density differences as opposed to wind and tides. Chapter 10 the winddriven circulation in chapter 9 we saw that the ocean comprises a warm, salty, strati. Ocean circulation wind driven and thermohaline processes r. 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. In reality is not independent on the wind circulation, but a representation of it can be obtained considering buoyancy effects alone.
1230 920 843 693 1200 195 911 166 972 751 1191 1255 72 636 1460 1162 381 240 733 956 1504 381 1493 721 14 506 1193 523 97 834 469 820 1249 842 831 716