670
Pauletal.
Figure 7b illustrates the deviation of salinity from
the climatology ofLevitus and Boyer (1994) for the
Atlantic Ocean. It reveals that the tongue of Antarctic Intermediate Water (AAIW) is rather broad
and much too salty in the model ocean. The AABW
is too fresh by up to 0.30 units.
Seawater Oxygen Isotope Composition and
Benthic Foraminiferal OIBO
In Fig. 8 the GEOSECS Ow along a cross section
in the Atlantic Ocean is compared with the annual
and zonal mean Ow from Experiments A and B. Experiment A yields a heavy Ow value of AABW,
whereas in Experiment B the Ow of AABW is close
to the GEOSECS data. Both experiments lead to
a broad tongue of AAIW that is also seen in the
salinity distribution. The Ow of AAIW is heavier than
observed by 0.1-0.2%0. Figure 9 extends the comparison ofthe GEOSECS and the simulated Ow to
the Pacific Ocean. In the upper 3000 m the agreement is reasonably good. The Ow of AABW is too
light by about 0.1%0. Unfortunately, there are no
GEOSECS Ow data between 30 0 S and 15°N.
Anticipating an application ofthe global ocean
model in a paleoceanographic setting, Fig. 10
presents core top benthic foraminiferal 0180 compiled from 169 Atlantic core sites. To facilitate a
comparison with the model ocean, the equilibrium
fractionation ofo, is computed for Experiment B.
Two cases are studied: In the first case (Fig. IIa)
the model temperature is inserted into the
paleotemperature equation ofErez and Luz (1983).
In the second case (Fig. 11 b) the climatologic temperature of Levit us et al. (1994) is used (cf. Fig. 4
of Zahn and Mix (1991) who employed the
GEOSECS temperature and Ow data to estimate
oJ In the real ocean the decrease of Ow with depth
is offset by a corresponding decrease oftemperature. Below about 2000 m water depth, a roughly
constant level of about 3%0 is reached, such that
NADW and AABW can be seen in Ow ' but not in
0, (Fig. 11 b). This is also suggested by the Atlantic core top benthic foraminiferalolsO shown in Fig.
10. The warm bias in the model temperature introduces a false vertical gradient into the simulated
0, distribution (Fig. lla).
Combined T-S-OIBO Diagrams
Figure 12 shows combined T-S-01SO diagrams for
the GEOSECS data and Experiments A and B. The
GEOSECS data were taken from three stations in
the North Atlantic and five stations in the South Atlantic. The ocean model output was sampled at the
same geographic positions and depths. Fig. 12 also
depicts the temperature-salinity ranges ofMediterranean Water (MW), AAIW, NADW and AABW,
as defined by Emery and Meincke (1986) (see
Table 2).
The GEOSECS serial points all plot on curves
that hook into the cold AABW (Fig. 12a). The two
other end members are the relatively fresh AAIW
(stations 56 and 67) and the relatively salty NADW
(stations 29, 37 and 115). Finally the influence of
MW is reflected in the T-S curve of station 115.
These four water masses are also seen in the OISO
values, which proves that they can indeed be used
to characterize different water masses. However,
there can be no one-to-one correspondence, e.g.
there can be water types that are similar in temperature Tand isotopic compositionolsO, but differ in salinity S, conceivably because of a sea ice
effect (stations 85 and 91 in the Southern Ocean).
Table 2 also gives the Ow statistics for the serial
points from all GEOSECS stations in the Atlantic
that fall into the temperature-salinity ranges ofthe
four water masses MW, AAIW, NADW and
AABW: MW has the highest Ow mean value
(0.36%0), AABW the lowest (-0.13%0). The Ow
mean value ofNADW (0.20%0) is between that
of AAIW (0.00%0) and AABW. The lcr intervals
do not overlap except for AAIW and AABW. This
reflects that AAIW and AABW both have sources
in the Southern Ocean, the lower Ow mean value
of AABW being due to the addition of glacial meltwater.
The influence ofMW is missing from the ocean
model output simply because the Mediterranean is
not included in the ocean model domain (Figs. 12b
and c). The other water masses are found in the
ocean model, but the deficiencies in their representation are manifest in the temperature-salinity
ranges that differ significantly from those given by
Emery and Meincke (1986): AAIW and NADW
are too warm, and AABW is too cold and fresh
Pauletal.
Figure 7b illustrates the deviation of salinity from
the climatology ofLevitus and Boyer (1994) for the
Atlantic Ocean. It reveals that the tongue of Antarctic Intermediate Water (AAIW) is rather broad
and much too salty in the model ocean. The AABW
is too fresh by up to 0.30 units.
Seawater Oxygen Isotope Composition and
Benthic Foraminiferal OIBO
In Fig. 8 the GEOSECS Ow along a cross section
in the Atlantic Ocean is compared with the annual
and zonal mean Ow from Experiments A and B. Experiment A yields a heavy Ow value of AABW,
whereas in Experiment B the Ow of AABW is close
to the GEOSECS data. Both experiments lead to
a broad tongue of AAIW that is also seen in the
salinity distribution. The Ow of AAIW is heavier than
observed by 0.1-0.2%0. Figure 9 extends the comparison ofthe GEOSECS and the simulated Ow to
the Pacific Ocean. In the upper 3000 m the agreement is reasonably good. The Ow of AABW is too
light by about 0.1%0. Unfortunately, there are no
GEOSECS Ow data between 30 0 S and 15°N.
Anticipating an application ofthe global ocean
model in a paleoceanographic setting, Fig. 10
presents core top benthic foraminiferal 0180 compiled from 169 Atlantic core sites. To facilitate a
comparison with the model ocean, the equilibrium
fractionation ofo, is computed for Experiment B.
Two cases are studied: In the first case (Fig. IIa)
the model temperature is inserted into the
paleotemperature equation ofErez and Luz (1983).
In the second case (Fig. 11 b) the climatologic temperature of Levit us et al. (1994) is used (cf. Fig. 4
of Zahn and Mix (1991) who employed the
GEOSECS temperature and Ow data to estimate
oJ In the real ocean the decrease of Ow with depth
is offset by a corresponding decrease oftemperature. Below about 2000 m water depth, a roughly
constant level of about 3%0 is reached, such that
NADW and AABW can be seen in Ow ' but not in
0, (Fig. 11 b). This is also suggested by the Atlantic core top benthic foraminiferalolsO shown in Fig.
10. The warm bias in the model temperature introduces a false vertical gradient into the simulated
0, distribution (Fig. lla).
Combined T-S-OIBO Diagrams
Figure 12 shows combined T-S-01SO diagrams for
the GEOSECS data and Experiments A and B. The
GEOSECS data were taken from three stations in
the North Atlantic and five stations in the South Atlantic. The ocean model output was sampled at the
same geographic positions and depths. Fig. 12 also
depicts the temperature-salinity ranges ofMediterranean Water (MW), AAIW, NADW and AABW,
as defined by Emery and Meincke (1986) (see
Table 2).
The GEOSECS serial points all plot on curves
that hook into the cold AABW (Fig. 12a). The two
other end members are the relatively fresh AAIW
(stations 56 and 67) and the relatively salty NADW
(stations 29, 37 and 115). Finally the influence of
MW is reflected in the T-S curve of station 115.
These four water masses are also seen in the OISO
values, which proves that they can indeed be used
to characterize different water masses. However,
there can be no one-to-one correspondence, e.g.
there can be water types that are similar in temperature Tand isotopic compositionolsO, but differ in salinity S, conceivably because of a sea ice
effect (stations 85 and 91 in the Southern Ocean).
Table 2 also gives the Ow statistics for the serial
points from all GEOSECS stations in the Atlantic
that fall into the temperature-salinity ranges ofthe
four water masses MW, AAIW, NADW and
AABW: MW has the highest Ow mean value
(0.36%0), AABW the lowest (-0.13%0). The Ow
mean value ofNADW (0.20%0) is between that
of AAIW (0.00%0) and AABW. The lcr intervals
do not overlap except for AAIW and AABW. This
reflects that AAIW and AABW both have sources
in the Southern Ocean, the lower Ow mean value
of AABW being due to the addition of glacial meltwater.
The influence ofMW is missing from the ocean
model output simply because the Mediterranean is
not included in the ocean model domain (Figs. 12b
and c). The other water masses are found in the
ocean model, but the deficiencies in their representation are manifest in the temperature-salinity
ranges that differ significantly from those given by
Emery and Meincke (1986): AAIW and NADW
are too warm, and AABW is too cold and fresh