Geoscience Reference
In-Depth Information
Figure 2.15.
a) Illustration of convection in the open ocean; b) illustration
of convection along the edges of a continent
The phenomenon of convection is not the only one capable of
changing deep oceanic waters. These can also be altered by ventilation
or subduction (Figure 2.16). This phenomenon occurs at the end of
winter, or the beginning of spring, when the mixed layer reaches its
maximal depth, in the main thermocline. This thick mass of
homogenous water can slide into the thermocline waters, when the
surface wind favors an Ekman pumping toward the bottom of the
ocean (
downwelling
). A large part of the thermocline waters, called
mode waters, is thus renewed.
main
thermocline
Minimal
depth of the
mixed layer
subduction
isopycne
Maximal
depth of the
mixed layer
latitude
Figure 2.16.
Schematic representation of the phenomenon of subduction
which enables the renewal of thermocline waters (from [FIE 10])
The vertical distribution of temperature, zonally averaged for the
global ocean, shows a general form in W, which is very characteristic.
