Rahmstorf S., and M.H. England
J. Phys. Oceanogr., 27, 2040-2054, 1997
KeyWords
Abstract
Mixed boundary-conditions. Thermohaline circulation. World ocean.
Model.
Thermocline. Temperature. Feedback. Cells.
A series of experiments with a hybrid model (ocean circulation model
with
simple atmospheric feedback model) and an ocean-only model is used to
study
the sensitivity of the ocean's deep overturning circulation to
Southern
Hemisphere winds. In particular, the ''Drake Passage effect'' is
examined.
The results show that two factors weaken the control that the Drake
Passage
effect exerts over the how of North Atlantic Deep Water (NADW). The
first is
that thermohaline forcing alone can generate about 75% of the NADW
flow found
in our model; this ability is lost if atmospheric feedback is
neglected. The
second is that about two-thirds of the downwelling induced by Ekman
transport
across Drake Passage occurs in the Southern Hemisphere just north of
Drake
Passage; only one-third occurs in the North Atlantic and enhances NADW
flow.
For these two reasons, the influence of Southern Ocean Winds on NADW
flow is
only moderate and nor as strong as previously suggested. However, the
authors
find that the formation rate of Antarctic Bottom Water depends
strongly on
the winds over the Southern Ocean.