Water Atlantic Intermediate

Both Cd/Ca and distributions suggest a strong stratification in the North Atlantic Ocean, with a low nutrient, high water mass (often called glacial North Atlantic intermediate water, GNAIW) occupying depths down to about 2,000 m, and a high nutrient, low water... 

Lynch-Stieglitz J., van Geen A., and Fairbanks R. G. (1996) Interocean exchange of Glacial North Atlantic Intermediate Water evidence from sub-Antarctic Cd/Ca and carbon isotope measurements. Paleoceanography 11, 191-201. 

Neodymium-isotope ratios of intermediate and deep water in the Indian Ocean are intermediate to the Atlantic and Pacific. They generally fall between s d = 1 to —9, and are consistent with domination by northward flowing circumpolar water (Bertram and Elderfield, 1993 Jeandel et al., 1998). A depth profile east of southern Africa (Figure 7) displays the same zig-zag pattern as South Atlantic intermediate and deep water, reflecting advection of NADW into the western Indian Ocean (Bertram and Elderfield, 1993). 

Fig. 3.2 (a) Simplified, schematic representation of oceanic deep water circulation (after Broecker 1997). (b) Water masses in theAtlantic (after Stowe 1979). AABW =Antarctic Bottom Water AAIW =Antarctic Intermediate Water AIW = Atlantic Intermediate Water med = Mediterranean Water NADW = North Atlantic DeepWater. 

The collection of water samples obtained from 05°01 S 32°34 W based on the temperature and salinity data represent sample collections from sub-tropical water, Antarctic intermediate water. North Atlantic deep and bottom water and Antarctic bottom water all the major types of sub-surface water present at this location (13). The lowest strontium/ chlorinity ratio value was found at 4387 meters in the Antarctic bottom... 

Conventional T-S diagrams for specific locations in the individual oceans are shown in Fig. 10-4. The inflections in the curves reflect the inputs of water from different sources. The linear regions represent mixing intervals between these core sources. For example, in the Atlantic Ocean the curves reflect input from Antarctic Bottom Water (AABW), North Atlantic Deep Water (NADW), Antarctic Intermediate Water (AIW), Mediterranean Water (MW), and Warm Surface Water (WSW). 

Vertical column inventory of anthropogenic CO2 in the ocean (mol/m ). High inventories are associated with deepwater formation in the North Atlantic and intermediate and mode water formation between 30°S and 50°S. Total inventory of shaded regions is 106 17PgC. Source-. From Sabine, C. L., et al. (2004). Science 305, 367-371. (See companion website for color version.)... 

Schmidt S (2006) Impact of the Mediterranean Outflow Water on particle dynamics in intermediate waters of the North-East Atlantic, as revealed by 234Th and 228Th. Mar Chem 100 289-298 Schmidt S, Reyss JL (1991) Uranium concentrations of Mediterranean seawaters with high salinities. C R Acad Sci Paris 312 379-384... 

Diverse processes can form intermediate waters within the water column. In the southern South Atlantic, the NADW overrides the denser ABW. Antarctic Intermediate Water results from water sinking along the Antarctic Convergence ( 50°S). Relatively warm, saline... 

Figure 13.2 Section of (A) nitrate versus depth and (B) nitrate versus potential density (sigma theta) using combined data from the 2003 (North Atlantic) and 2005 (South Atlantic) occupations of the A16 line. North Atlantic DeepWater (NADW), Antarctic Bottom Water (A ABW) and Antarctic Intermediate Water (AAIW) are indicated. Units pmol kg. ...

Nitrate-rich signatures of Antarctic Bottom Water (AABW) and Antarctic Intermediate Water (AAIW) extend northward, reflecting the high surface concentrations where these water masses are formed. These water masses are also evident in the zonal structure of the North and South Atlantic, and nitrate-rich (>30 iM) AAIW is evident in the South Atlantic (Fig. 13.3) at mid-depth, along with a hint of AABW with elevated nitrate concentrations in the deep western part of the basin. There is... 

Figure 13-9 Schematic views of (A) meridional and vertical transport of nitrate in the upper Atlantic basin and (B) associated horizontal transport pathways. Nitrate-rich Circumpolar Deep Water (CDW) upwells in the Southern Hemisphere and the residual mean flow transports some of this upwelled water across the polar front into the regions of intermediate and mode water formation. Nitrate-rich Sub-Antarctic Mode Water (SAMW) and Antarctic Intermediate Water move northward in the thermocline, ultimately outcropping in the subpolar North Atlantic. Ekman transfer provides a source of nitrate to the subtropical gyre along with lateral and vertical eddy transport processes.

Figure 3 Map of Nd-isotope variability in ferromanganese deposits. The map shows systematic geographic variability with lowest values in the North Atlantic, highest values in the Pacific, and intermediate values elsewhere. Arrows illustrate general movement of deep water, and show that the contours generally follow deep-water flow. Shaded fields delineate regions where the Fe -Mn and deep seawater data differ by >2Efjd units (after Albare(c)de and...

These observations, taken together, indicate that the neodymium-isotope ratios of intermediate and deep seawater are imprinted mainly in the Atlantic and Pacihc oceans. The circum-Antarctic is fed by both and its intermediate neodymium-isotope ratio reflects those of the Atlantic and Pacihc water sources. Indian Ocean intermediate and deep water is fed primarily by the circum-Antarctic and tends to retain a circum-Antarctic neodymium-isotope ratio. 

Silicate is depleted from surface waters by biological processes and remineralized in the deep water. Moreover, silicate tends to accumulate in water masses as they age (cf. Broecker and Peng, 1982). These processes account for both the increasing concentration of silicate with depth, and its increasing concentrations from the North Atlantic to the circum-Antarctic to the Pacific. With a few exceptions (notably the North Atlantic), neodymium abundances show a smooth increase with depth, and in deep water they are highest in the Pacific, lowest in the Atlantic, and intermediate in the Indian (Figure 6). 

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