Establishment of the Abyssal Circulation
431
HEIGHT
VELOCITY
0
g
0
Iii I
0.0
10.0
20.0
30.0
LONGITUDE
LONGIT\IOE
,... 200.0 II£GN0N-0.50£-G1 Cllll'o0.10£-G1 SCAL.Iio0.10[+01 IIAl"o
,._ 200.0 - . 5 0 [ - 0 1 VLIJio0.10E-D1 Do\..,._ 400
Fig. 7.6.5. Final steady state at day 200 ofthe calculation shown in Fig. 7.6.4. (From Kawase 1987)
restriction that fluid in the abyss can upwell only where the abyss itself induces
an anomaly actually allows the height field to act as a tracer of the wave
perturbations, either in the spin-up phase or in the final steady state where the
Rossby wave field is frozen in a balance between westward propagation and
local dissipation. This role of the Rossby wave remains important even when
the restriction of the upwelling to satisfy (7.6.12) is relaxed. The next section
examines a fully baroclinic model to describe the layered structure of the abyss.
Although the upwelling is determined a priori as in the Stommel-Arons theory,
the baroclinic wave dynamics discussed by Kawase becomes the key in
understanding the determination of the vertical structure of the abyssal flow.