Water Warm Saline Deep

O Connell S., Chandler M.A., Ruedy R. (1996) Implications for the creation of warm saline deep water Late Paleocene reconstructions and global climate model simulations. Geol. Soc.Am. Bull. 108, 270—84. 

Answer 6.2 Lines extrapolating to the zero points are observed for Li, Na, and K, plotted as a function of Cl. The temperature is roughly positively correlated to the concentration of these ions. Thus, if only these parameters were measured, the conclusion could be reached that one deals with a warm (and deep) saline water end member that is diluted by very fresh and shallow (cold) local recharge water. Yet the correlation lines of SO4, Ca, and Mg extrapolate to the vertical axis, indicating that both water end members are... 

The density of seawater thus depends both on its temperature and salinity. Highly saline waters at about 4°C are the most dense and will tend to sink, whereas warm, less saline water is less dense, and will tend to rise. This behavior has important implications for vertical motions in the sea. Descent of surface waters to the deep ocean is possible only where saline waters are cooled. This actually occurs in only a few locations, most notably in the North Atlantic off Greenland, and in the Weddell Sea, part of the Antarctic Ocean south of the Atlantic. North Atlantic deep water has a temperature of 2.5°C and a salinity of 35 g salt per kg of seawater. Deep water forming in the Weddell Sea has a temperature of — 1.0°C and a salinity of 34.6 g salt per kg seawater. In both of these locations, saline surface waters are cooled and sink, a process known as downwelling. The surface waters are made saline by evaporation nearer the equator in the case of the North Atlantic, and by the formation of sea ice in the case of the Weddell Sea. Shallower downwelling, to intermediate depths in the oceans, also occurs in areas of high evaporation. 

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. 

Besides MB Is, baroclinic summer inflows of exceptionally warm and saline water affect the deeper layers of the central Baltic Sea (cf. Section 10.5). Such inflows do not fulfill the criteria for MB Is (cf. Section 10.3) but can effectively influence the deep water below the halocline in the Bornholm, Gdansk, and Eastern Gotland Basins (Feistel et al., 2003c, 2004a). 

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