Geoscience Reference
In-Depth Information
was developed under assumptions of idealized
ocean depth, wind constancy, uniform water
viscosity and constant water pressure at a given
depth. This is seldom the case in reality, and under
most oceanic conditions the thickness of the
wind-driven Ekman layer is about 100 to 200m.
North (south) of 30
thermocline and below the tropopause - their two
most significant stabilizing boundaries. Within
these two zones, fluid-like circulations are main-
tained by meridional thermal energy gradients,
dominantly directed poleward (
Figure 7. 28
), and
acted upon by the Coriolis force. Prior to the
1970s oceanography was studied in a coarsely
averaged spatial-temporal framework similar
to that applied in classical climatology. Now,
however, its similarities with modern meteorology
are apparent (Box 7.3). The major differences in
behavior between the oceans and the atmosphere
derive from the greater density and viscosity of
ocean waters and the much greater frictional
constraints placed on their global movement.
Many large-scale characteristics of ocean
dynamics resemble features of the atmosphere.
These include: the general circulation, major
N, the westerly (easterly)
winds create a southward (northward) transport
of water in the Ekman layer, giving rise to a
convergence and sinking of water around 30°N,
referred to as Ekman pumping.
°
Horizontal
General
Comparisons can be made between the structure
and dynamics of the oceans and the atmosphere
in respect of their behavior above the permanent
180°
150°
120°
90°
60°
30°W
0°
30°E
60°
90°
120°
150°
180
90°
90°
0.1
0
0.01
0.26
60°
60°
NORTH
PACIFIC
1.14
MAX
1.55
30°N
30°N
1.58
MAX
0
0.48
1.44
0°
0°
0.23
0.77
MAX
2.07
MAX
ATLANTIC
INDIAN
SOUTH
PACIFIC
1.15
1.92
0.49
30°S
30°S
1.19
1.06
0.06
60°
60°
90°
180°
90°
60°
90°
150°
120°
90°
60°
30°W
0°
30°W
120°
150°
180°
Figure 7.28
Mean annual meridional heat transport (10
15
W) in the Pacific, Atlantic and Indian Oceans, respectively
(delineated by the dashed lines). The latitudes of maximum transport are indicated.
Source: Hastenrath (1980). From Journal of Physical Oceanography by permission of the American Meteorological Society.
