30
Homogeneous Models of the Ocean Circulation
not zero and is actually responsible for setting the geostrophic region of the
flow into motion through the mechanism of stretching of the planetary vorticity filaments.
As noted in Chapter 1, we can expect the Ekman pumping to drive an
anticyclonic circulation in the subtropical regions of the oceans and a cyclonic
circulation poleward of that. For example, in both the northern Atlantic and
Pacific oceans the Ekman pumping inferred from observations is downward in
the latitudes south of about 45°N and upward north of that latitude (see
Figs. 2.2.2, 2.2.3). Most of the theoretical work described in this chapter
concentrates on the structure of the subtropical gyre, and therefore a restricted
basin bounded on the north by a latitude meant to represent the position of the
·N~--------~~--------~---------,
----- --go•s ~-------~--------~-------~
-1
0
2
,.~ (dynes cm- 2 )
Fig. 2.2.2. Zonal mean of the eastward wind stress over the world's oceans. This stress drives the
meridional transport in the upper Ekman layer. The convergence of this transport produces Ekman
downwelling. The solid and dashed curves, two estimates of the stress. (From Hellerman and
Rosenstein 1983)
Homogeneous Models of the Ocean Circulation
not zero and is actually responsible for setting the geostrophic region of the
flow into motion through the mechanism of stretching of the planetary vorticity filaments.
As noted in Chapter 1, we can expect the Ekman pumping to drive an
anticyclonic circulation in the subtropical regions of the oceans and a cyclonic
circulation poleward of that. For example, in both the northern Atlantic and
Pacific oceans the Ekman pumping inferred from observations is downward in
the latitudes south of about 45°N and upward north of that latitude (see
Figs. 2.2.2, 2.2.3). Most of the theoretical work described in this chapter
concentrates on the structure of the subtropical gyre, and therefore a restricted
basin bounded on the north by a latitude meant to represent the position of the
·N~--------~~--------~---------,
----- --go•s ~-------~--------~-------~
-1
0
2
,.~ (dynes cm- 2 )
Fig. 2.2.2. Zonal mean of the eastward wind stress over the world's oceans. This stress drives the
meridional transport in the upper Ekman layer. The convergence of this transport produces Ekman
downwelling. The solid and dashed curves, two estimates of the stress. (From Hellerman and
Rosenstein 1983)