Pacific Ocean circulation

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. 

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. 

Delaygue et al. (2000) have modeled the present day 0 distribution in the Atlantic and Pacific Ocean and its relationship with salinity (see Fig. 3.19). A good agreement is found between observed and simulated 5 0-values using an oceanic circulation model. As shown in Fig. 3.19 the Atlantic Ocean is enriched by more than 0.5%c relative to the Pacific Ocean, but both ocean basins show the same general patterns with high 0-values in the subtropics and lower values at high latitudes. 

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). 

At their sampling sites in the Pacific Ocean, Santosa et al. (1997) found that MMA(V) and DMA(V) concentrations were highest at the surface with 0.012-0.016 pg L-1 and 0.048-0.185 pg L-1, respectively. The concentrations sharply declined to depths of 200 m. From depths of 200 to at least 5000 m, MMA(V) and DMA(V) concentrations stabilized at about 0.003 pg L-1 (Santosa et al., 1997). Santosa et al. (1996), 703 argue that the presence of methylarsenic in deep ocean waters is probably not due to diffusion from ocean floor sediments. Instead, the deep water methyl forms may result from the diffusion of methylarsenic-bearing surface waters, the circulation of surface waters to greater depths, and the tendency of methylarsenic not to appreciably sorb onto iron (oxy)(hydr)oxides particles. 

Boyle E.A. and Keigwin L.D. (1985) Comparison of Atlantic nd Pacific paleochemical records for the last 25,000 years Changes i deep ocean circulation and chemical inventories. Earth and Planet. Sci. at. 76, 135-150. 

Wyrtki, K. (1962). The oxygen minima in relation to ocean circulation. Deep-Sea Res. 9, 11—28. Yoshikawa, C., Nakatsuka, T., and Kawahata, H. (2005). Transition of low-salinity water in the Western Pacific Warm Pool recorded in the nitrogen isotopic ratios of settling particles. Geophys. Res. Lett. 32(14), doi 10.1029/2005GL023103. 

The flux of He from intraplate volcanic systems is dominantly subaerial and so it is not possible to obtain directly time-integrated flux values for even a short geological period. While the Loihi hotspot in the Pacific is submarine, calculation of He fluxes into the ocean using ocean circulation models have not required a large flux from this location that is comparable to the He plumes seen over ridges (Gamo et al., 1987 Farley et al., 1995), although recent data has seen an extensive He plume from Loihi (Lupton, 1996). 

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