North Atlantic ocean circulation

Similar changes are seen in other terrestrial and marine geological records from the North Atlantic region, but not from the Antarctic. Circulation changes in the North Atlantic Ocean are conjectured to be the driving force for the climate changes. 

Cronin T. M., Raymo M. E., and Kyle K. P. (1996) Pliocene (3.2-2.4 Ma) ostracode faunal cycles and deep ocean circulation. North Atlantic Ocean. Geology 24(8), 695-698. 

Schiller, A., Mikolajewicz, U., and Voss, R. (1997). The stability of the North Atlantic thermohaline circulation in a coupled ocean-atmosphere general circulation model. Climate Dynamics 13, 325-347. 

Reid, J.L., 1994. On the total geostrophic circulation of the North Atlantic Ocean Flow patterns, tracers, and transports. Prog. Oceanogr., 33(1), 1-92. 

Fine RA (1995) Tracers, time scales and the thermohaline circulation the lower limh in the North Atlantic Ocean. Reviews of Geophysics 33 1353-1365. 

The ratios I/ I, l/ Cs, and l/ Tc in seaweeds sampled at two locations along the Norwegian Coastal current from 1990 to 1998 were measured to estimate transit time in the thermohaline circulation of the Arctic and North Atlantic oceans (Yiou et al. 2002). l, Tc, and Cs are discharged from nuclear fuel reprocessing facilities into the Irish Sea and the... 

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. 

The D-O events are far too rapid to be caused by insolation changes, and they most likely result from changes in ocean circulation. Their prominence and clarity in the Greenland cores relative to the Antarctic ones is due to the proximity of Greenland to the sites of deep-water formation in the North Atlantic and the tremendous amount of heat being delivered to them by the Gulf Stream (Broecker and Denton, 1989). 

North Atlantic to 500 m in the North Pacific. This reflects an increasing addition of CO2 to deep waters as meridional overturning circulation moves them from the Atlantic to the Indian and then to the Pacific Ocean. Thus, as a water mass ages, it becomes more corrosive to calcium carbonate. Since aragonite is more soluble than calcite, its saturation horizon lies at shallower depths, rising from 3000 m in the North Atlantic to 200 m in the North Pacific. 

Distributions of DOC in the deep ocean. The x-axis is viewed in the context of the deep-ocean circulation, with formation in the North Atlantic, circulation around the Southern Ocean, and flow northward into the Indian and Pacific oceans. Source-. From Mansell, D. A. (2002) Biogeochemistry of Marine Dissoived Organic Matter, Academic Press, pp. 685-715. 

Cyclical phenomena, such as ENSO events, the North Atlantic Oscillation, the North Pacific Oscillation, and a phenomenon in the Southern Ocean called the Southern Annular Mode, have important impacts on the solubility pump. This was illustrated for the ENSO events in Figure 25.5b. These oscillations are all sensitive to global climate change. In the case of the Southern Ocean, the impact of climate change on circulation is complicated by the zonation associated with the polar and subpolar frontal boundaries (Figure 10.10). As a result, some parts of the Southern Ocean are expected to respond differently than others to changes in increases and meridional overturning circulation rates. 

Figure 3.16 compares 8 0 profiles from Antarctica and Greenland. The dramatic 5-shifts observed in Greenland cores are less pronounced in the 5-record along the Vostok core, probably because the shifts in Greenland are connected to rapid ocean/atmosphere circulation changes in the North Atlantic (for more details, see Sect. 3.12.1). 

North Atlantic Deep Water (NADW), which is formed with an initial 5 C-value between 1.0 and 1.5%c, becomes gradually depleted in C as it travels southward and mixes with Antarctic bottom water, which has an average 8 C-value of 0.3%c (Kroopnick 1985). As this deep water travels to the Pacific Ocean, its C/ C ratio is further reduced by 0.5%o by the continuous flux and oxidation of organic matter in the water column. This is the basis for using 8 C-values as a tracer of paleo-oceanographic changes in deep water circulation (e.g., Curry et al. 1988). 

NADW flows southward the ongoing oxidation of organic matter results in a progressive C-depletion down to less than 0.4%c in the Southern Ocean. Reductions in observed in many cores from the North-Atlantic (Samtheim et al. 2001 Elliot et al. 2002) have been interpreted as meltwater input to the surface ocean (Heinrich events), which caused changes in deep water circulation. 

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