Elements of Physical Oceanography 2.5 Wind-Forced Ocean Processes 35
Part A | 2.5
C
ro
ss
-s
ec
tion
al
view of wi nd ce ll s
Atmospheric
pressure
at surface
Ferrel cell
Ferrel cell
Hadley
cell
Hadley
cell
Doldrums
Horse latitudes
Horse latitudes
Low
Low
Low
High
High
Polar cell
Polar cell
Subtropical highs
Subtropical highs
Subpolar lows
Equatorial lows
Subpolar lows
Polar
high pressure
Southeast
trades
Prevailing
westerlies
Polar easterlies
90°
90°
60°
60°
30°
30°
0°
Polar easterlies
Wind
Coriolis
effect
Northeast
trades
Prevailing
westerlies
Polar
high pressure
a)
b)
Fig. 2.34 (a) Average surface global
winds divide into zonal bands due
to Earth rotation effects. In both
hemispheres, there are zones for
the tropical easterly trade winds
(equator–30
ı N and S), prevailing
westerlies (3060
ı N and S), and
polar easterlies (6090
ı N and S).
(b) The major ocean basins feature
gyre current systems that are interact
through east–west equatorial current
systems in the Atlantic and Pacific and
the Antarctic Circumpolar Current in
the Southern Ocean (after [2.7])
the Atlantic, Pacific, and Indian oceans and the Southern Ocean that circles Antarctica. The transports of the
principal currents are presented in Table 2.6.
The dynamics of much of the open ocean flows is
governed by one of the geostrophic force balances in
which the Coriolis force balances the horizontal pressure gradient force for an arbitrary flow direction that is
perpendicular to the force direction (Fig. 2.35).
Table 2.6 Transport of major ocean surface currents
Location
Name
Maximum current [cm=s]
Volume transport [10 6 m 3 =s]
Western Boundary Currents
Gulf Stream
200300
400
Kuroshio Current
> 200
50
Brazil Current
50100
10
Southern Ocean
Antarctic Circumpolar Current
15
150
Equatorial Currents
North Pacific Equatorial Current 20
45
Equatorial Undercurrent
100150
40
Eastern Ocean
Peru Current
1050
20
The scalar form of the force balance is
f jVj D
@p
@n
So that the geostrophic flow magnitude is
V g D jVj D
1
f
D
@p
@n
:
Part A | 2.5
C
ro
ss
-s
ec
tion
al
view of wi nd ce ll s
Atmospheric
pressure
at surface
Ferrel cell
Ferrel cell
Hadley
cell
Hadley
cell
Doldrums
Horse latitudes
Horse latitudes
Low
Low
Low
High
High
Polar cell
Polar cell
Subtropical highs
Subtropical highs
Subpolar lows
Equatorial lows
Subpolar lows
Polar
high pressure
Southeast
trades
Prevailing
westerlies
Polar easterlies
90°
90°
60°
60°
30°
30°
0°
Polar easterlies
Wind
Coriolis
effect
Northeast
trades
Prevailing
westerlies
Polar
high pressure
a)
b)
Fig. 2.34 (a) Average surface global
winds divide into zonal bands due
to Earth rotation effects. In both
hemispheres, there are zones for
the tropical easterly trade winds
(equator–30
ı N and S), prevailing
westerlies (3060
ı N and S), and
polar easterlies (6090
ı N and S).
(b) The major ocean basins feature
gyre current systems that are interact
through east–west equatorial current
systems in the Atlantic and Pacific and
the Antarctic Circumpolar Current in
the Southern Ocean (after [2.7])
the Atlantic, Pacific, and Indian oceans and the Southern Ocean that circles Antarctica. The transports of the
principal currents are presented in Table 2.6.
The dynamics of much of the open ocean flows is
governed by one of the geostrophic force balances in
which the Coriolis force balances the horizontal pressure gradient force for an arbitrary flow direction that is
perpendicular to the force direction (Fig. 2.35).
Table 2.6 Transport of major ocean surface currents
Location
Name
Maximum current [cm=s]
Volume transport [10 6 m 3 =s]
Western Boundary Currents
Gulf Stream
200300
400
Kuroshio Current
> 200
50
Brazil Current
50100
10
Southern Ocean
Antarctic Circumpolar Current
15
150
Equatorial Currents
North Pacific Equatorial Current 20
45
Equatorial Undercurrent
100150
40
Eastern Ocean
Peru Current
1050
20
The scalar form of the force balance is
f jVj D
@p
@n
So that the geostrophic flow magnitude is
V g D jVj D
1
f
D
@p
@n
: