Ocean water is constantly evaporating, increasing the temperature and humidity of the surrounding air to form rain and storms that are then carried by trade winds. In fact, almost all rain that falls on land starts off in the ocean.
The tropics are particularly rainy because heat absorption, and thus ocean evaporation, is highest in this area. Major current systems typically flow clockwise in the northern hemisphere and counterclockwise in the southern hemisphere, in circular patterns that often trace the coastlines.
Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics. When this mixing takes place in higher latitude, a circulation pattern is created where warm water moves pole-wards from the tropics thus surrendering heat to the atmosphere resulting in the transportation of heat pole-wards.
The cycle repeats itself over and over influencing the transfer of heat from the equator to the highlands. This process explains why the ocean is colder on the east coast than the west coast. The colder water sinks and moves towards Indian, Pacific, and Atlantic basin. The changes in current movements affect the coastal climate by carrying a lot of heat.
The warm and cold ocean currents play a major role in determining the climate of the coastal landmasses in their vicinity. John Misachi April 25 in Environment. Puma, Cougar, Or Mountain Lion?
Bhopal Gas Tragedy. Both mechanisms are summarised in table 1. The ocean circulation may change in the future Given the past instability of ocean currents and our understanding of their non-linear behaviour, the future of the Atlantic circulation in the changing climate of the next century is a natural concern. Manabe and Stouffer published scenario simulations with a coupled ocean- atmosphere model in which the carbon dioxide content of the atmosphere was gradually increased to both twice and four times the pre-industrial value and then kept constant Fig.
With a doubling of CO2, the Atlantic conveyor circulation declined strongly but subsequently recovered. If the CO2 content was increased fourfold, h????? A systematic sensitivity study with a simpler model revealed that not only the total amount of carbon dioxide, but also its rate of increase determines the effects on the ocean Stocker and Schmittner Figure 4.
Time series of meridional transport in the Atlantic for two greenhouse scenarios of Manabe and Stouffer Top panel: carbon dioxide forcing of the runs. For the scenario leading to a quadrupling of carbon dioxide in the atmosphere, the thermohaline ocean circulation winds down almost completely. The circulation changes in all these experiments happen on the slow, advective time scale over one or two centuries; rapid changes as seen during the last glacial were not triggered in these scenarios.
This is the main reason why the effects on regional temperatures are only moderate in these models; the reduced ocean heat transport then falls in a time of strong greenhouse warming and is partly cancelled by this.
The effects of such circulation changes on marine ecosystems are largely unexplored and will probably be serious. The lack of rapid circulation changes????? Due to poor resolution, present climate models cannot capture the fast convective instability very well; this process depends on regional details. Examples of such non- linear behaviour include rapid circulation changes in the North Atlantic. References Bond, G. Broecker, S. Johnsen, J. McManus, L. Labeyrie, J. Jouzel and G. Bonani, Correlations between climate records from North Atlantic sediments and Greenland ice.
Nature, , Ganopolski, A. Rahmstorf, V. Petoukhov and M. Claussen, Simulation of modern and glacial climates with a coupled global model of intermediate complexity. Houghton, J. Meira Filho, B. Callander, N. Harris, A. Kattenberg and K. Maskell, Climate Change Cambridge University Press, Cambridge, pp. Labeyrie, L. Duplessy, J. Duprat, A. Juillet-Leclerc, J. Moyes, E. Michel, N. Kallel and N. Shackleton, Changes in the vertical structure of the North Atlantic ocean between glacial and modern times.
Quaternary Science Review, 11, Manabe, S. Stouffer, Two stable equilibria of a coupled ocean-atmosphere model. Stouffer, Century-scale effects of increased atmospheric CO2 on the ocean-atmosphere system.
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