22
Chemical Oceanography, 4th Edition
water sinks at lower latitudes and flows toward the equator. In the South Atlantic, the
central water terminates at a depth where it merges with the Antarctic intermediate water.
In the North Atlantic, the Arctic intermediate water is not as dominant. The Atlantic central water merges into this Arctic water at high latitudes in the North Atlantic and into
Mediterranean water at low latitudes. The effect of the Mediterranean water can be demonstrated by examining the horizontal section of salinity at a depth of 1000 m (Figure 1.29).
The temperature (Figure 1.8) and salinity (Figure 1.14) sections for the Atlantic shown
previously (as well as the O 2 section to be shown in Chapter 6) demonstrate that the great
bulk of Atlantic water is deep water. The major source of this North Atlantic deep water is
the Norwegian Sea. This water flows over the sills between Scotland, Iceland, and Greenland
and sinks into the deep Atlantic. This flow is not continuous but occurs in pulses. The
salinity is 34.9, and the temperature is between 2 and 3°C for most of the North Atlantic
deep waters.
The bottom waters in the western and eastern basins of the South Atlantic are different
because of the separation of the Mid- Atlantic Ridge. On the western side, the bottom water
has temperatures down to 0.4°C, while on the eastern side the minimum is 2.4°C. The bottom waters are prevented from flowing into the eastern basin by the Walfish Ridge, which
has a sill depth of 3500 m. The salinity difference is not as dramatic (34.7 on the west and
34.9 on the east).
Earlier tritium measurements by Ostlund and coworkers in Miami have clearly demonstrated the speed of the formation of North Atlantic deep waters. Their results for tritium
in the North Atlantic obtained from the earlier GEOSECS and TTO studies are shown in
Figure 1.30. The measurements show the deep southward penetration of tritium, which
Figure 1.28
Satellite photograph of the temperature structure of the Gulf Stream.
Chemical Oceanography, 4th Edition
water sinks at lower latitudes and flows toward the equator. In the South Atlantic, the
central water terminates at a depth where it merges with the Antarctic intermediate water.
In the North Atlantic, the Arctic intermediate water is not as dominant. The Atlantic central water merges into this Arctic water at high latitudes in the North Atlantic and into
Mediterranean water at low latitudes. The effect of the Mediterranean water can be demonstrated by examining the horizontal section of salinity at a depth of 1000 m (Figure 1.29).
The temperature (Figure 1.8) and salinity (Figure 1.14) sections for the Atlantic shown
previously (as well as the O 2 section to be shown in Chapter 6) demonstrate that the great
bulk of Atlantic water is deep water. The major source of this North Atlantic deep water is
the Norwegian Sea. This water flows over the sills between Scotland, Iceland, and Greenland
and sinks into the deep Atlantic. This flow is not continuous but occurs in pulses. The
salinity is 34.9, and the temperature is between 2 and 3°C for most of the North Atlantic
deep waters.
The bottom waters in the western and eastern basins of the South Atlantic are different
because of the separation of the Mid- Atlantic Ridge. On the western side, the bottom water
has temperatures down to 0.4°C, while on the eastern side the minimum is 2.4°C. The bottom waters are prevented from flowing into the eastern basin by the Walfish Ridge, which
has a sill depth of 3500 m. The salinity difference is not as dramatic (34.7 on the west and
34.9 on the east).
Earlier tritium measurements by Ostlund and coworkers in Miami have clearly demonstrated the speed of the formation of North Atlantic deep waters. Their results for tritium
in the North Atlantic obtained from the earlier GEOSECS and TTO studies are shown in
Figure 1.30. The measurements show the deep southward penetration of tritium, which
Figure 1.28
Satellite photograph of the temperature structure of the Gulf Stream.