Numerical Study of Glacial and Meltwater Global Ocean
Thermohaline Conveyor
D. Seidov, B. J. Haupt
1
Introduction
The ocean thermohaline circulation is often referred to as a global conveyor
(Gordon 1986; Broecker and Denton 1989; Broecker 1991; review in Gordon et
al. 1992). It is common knowledge that the global ocean thermohaline circulation is strongly controlled by the production of the North Atlantic Deep Water
(NADW). Warm and salty subtropical water is carried to the high latitudes in the
North Atlantic (NA) by the North Atlantic Current. It is cooled there and descends to set forth the deep ocean current system which is believed to be a global
feature, a conveyor. Since the conveyor is mainly driven by latitudinal density
gradients, which in high latitudes are controlled primarily by salinity, the density-driven conveyor is also referred to as the global salinity conveyor belt
(Broecker 1991). The intriguing part of the problem is that the driving mechanism of change is thought to be very localized, with the key area of convection in
the northern NA being surprisingly small with respect to the global ocean volume.
Both high-latitudinal salinity and temperature varied dramatically during the
past several hundred years during the major glacial-interglacial cycles, and
many believe that the global thermohaline ocean circulation was radically different at various stages during the Late Quaternary. A strong positive feedback
between a curtailed conveyor and ongoing glaciation or deglaciation may be expected. As sediment is transported by ocean currents, the conveyor history is
thought to be imprinted in the seabed sediment. Hence, the ocean past circulation can be reconstructed, in principle, on the basis of sediment accumulation
records (Einsele 1992; Hsii 1989). Alternatively, one can try to reconstruct sediment transport using simulated past ocean circulation. Finally, the two approaches may be tied together by a Lagrangian approach to compare sediment
transport and water-volume motion. The results of such a multithread approach
to past ocean climatology can help both sedimentologists and oceanographers
to predict future change of the sediment transport and ocean climate in basis of
top analogues given by past circulation patterns.
This chapter reviews some of our recent paleoceanographic modeling and
presents some of our new results on the modeling of the global and North Atlantic paleocirculation and sedimentation regimes. The emphasis is on sedimenta-
Thermohaline Conveyor
D. Seidov, B. J. Haupt
1
Introduction
The ocean thermohaline circulation is often referred to as a global conveyor
(Gordon 1986; Broecker and Denton 1989; Broecker 1991; review in Gordon et
al. 1992). It is common knowledge that the global ocean thermohaline circulation is strongly controlled by the production of the North Atlantic Deep Water
(NADW). Warm and salty subtropical water is carried to the high latitudes in the
North Atlantic (NA) by the North Atlantic Current. It is cooled there and descends to set forth the deep ocean current system which is believed to be a global
feature, a conveyor. Since the conveyor is mainly driven by latitudinal density
gradients, which in high latitudes are controlled primarily by salinity, the density-driven conveyor is also referred to as the global salinity conveyor belt
(Broecker 1991). The intriguing part of the problem is that the driving mechanism of change is thought to be very localized, with the key area of convection in
the northern NA being surprisingly small with respect to the global ocean volume.
Both high-latitudinal salinity and temperature varied dramatically during the
past several hundred years during the major glacial-interglacial cycles, and
many believe that the global thermohaline ocean circulation was radically different at various stages during the Late Quaternary. A strong positive feedback
between a curtailed conveyor and ongoing glaciation or deglaciation may be expected. As sediment is transported by ocean currents, the conveyor history is
thought to be imprinted in the seabed sediment. Hence, the ocean past circulation can be reconstructed, in principle, on the basis of sediment accumulation
records (Einsele 1992; Hsii 1989). Alternatively, one can try to reconstruct sediment transport using simulated past ocean circulation. Finally, the two approaches may be tied together by a Lagrangian approach to compare sediment
transport and water-volume motion. The results of such a multithread approach
to past ocean climatology can help both sedimentologists and oceanographers
to predict future change of the sediment transport and ocean climate in basis of
top analogues given by past circulation patterns.
This chapter reviews some of our recent paleoceanographic modeling and
presents some of our new results on the modeling of the global and North Atlantic paleocirculation and sedimentation regimes. The emphasis is on sedimenta-