Ocean circulation

Momentum is mostly transferred from the atmosphere to the ocean, having the effect of driving the ocean circulation through the production of a wind-driven flow. Of course, the resultant flow carries heat and water, so contributing to fluxes of these quantities to the atmosphere in ways that would not have occurred without the establishment of the wind-driven circulation in the first place. 

Y. Nozaki, in Deep Ocean Circulation, Physical and Chemical Aspects, ed. T. Teramoto, Elsevier, Amsterdam, 1993, pp. 83-89. 

Joly observed elevated "Ra activities in deep-sea sediments that he attributed to water column scavenging and removal processes. This hypothesis was later challenged with the hrst seawater °Th measurements (parent of "Ra), and these new results conhrmed that radium was instead actively migrating across the marine sediment-water interface. This seabed source stimulated much activity to use radium as a tracer for ocean circulation. Unfortunately, the utility of Ra as a deep ocean circulation tracer never came to full fruition as biological cycling has been repeatedly shown to have a strong and unpredictable effect on the vertical distribution of this isotope. 

Extrapolation of this model calculation to the future climate warming suggests that an amplification of the current rate of increase in atmospheric CO2 content could result from climate-induced changes in ocean circulation rates. 

Ear from being just the processing of water on Earth, this cycle is the basis for a wide range of meteorologic, geochemical, and biological systems. Water is the transport medium for all nutrients in the biosphere. Water vapor condensed into clouds is the chief control on planetary albedo. The cycling of water is also one of the major mechanisms for the transportation of sensible heat (e.g. in oceanic circulation) and latent heat that is released when water falls from the air. 

The energy that powers terrestrial processes is derived primarily from the sun and from the Earth s internal heat production (mostly radioactive decay). Solar energy drives atmospheric motions, ocean circulation (tidal energy is minor), the hydrologic cycle, and photosynthesis. The Earth s internal heat drives convection that is largely manifested at the Earth s surface by the characteristic deformation and volcanism associated with plate tectonics, and by the hotspot volcanism associated with rising plumes of especially hot mantle material. 

As a result of these factors (wind, Ekman transport, Coriolis force) the surface ocean circulation in the mid-latitudes is characterized by clockwise gyres in the northern hemisphere and the counterclockwise gyres in the southern hemisphere. The main surface currents around these gyres for the world s oceans are shown in Fig. 10-6. The regions where Ekman transport tends to push water together are called convergences. Divergences result when surface waters are pushed apart. 

The ocean conveyor belt is one of the major elements of today s ocean circulation system (Broecker, 1997). A key feature is that it delivers an enormous amount of heat to the North Atlantic and this has profound implications for past, present, and probably future climates. 

Oceanic circulation. The process of ocean circulation described earlier yields an ocean circulation pattern that results in progressively older deep water as the water passes, in sequence from the Atlantic, Indian, to the Pacific Ocean. Surface water returns relatively quickly to the place of origin for the deep water. 

The superposition of the vertical biological cycle on the horizontal ocean circulation pattern leads to three general features in the distribution of the elements involved in this cycle. 

There are two important consequences of this superposition of biological cycling on the ocean circulation pattern that show up in the sediments. 

Fairbanks, R. G. (1989). A 17,000-year glacio-eustatic sea level record influence of glacial melting rates on younger dryas event and deep-ocean circulation. Nature 342, 637-642. 

The content of the material in a carbon reservoir is a measure of that reservoir s direct or indirect exchange rate with the atmosphere, although variations in solar also create variations in atmospheric content activity (Stuiver and Quay, 1980, 1981). Geologically important reservoirs (i.e., carbonate rocks and fossil carbon) contain no radiocarbon because the turnover times of these reservoirs are much longer than the isotope s half-life. The distribution of is used in studies of ocean circulation, soil sciences, and studies of the terrestrial biosphere. 

Jansen, E. (1992). Deglaciation, impact on ocean circulation. In "Encyclopedia of Earth System Science" Vol. 2. Academic Press. 

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