364
Equatorial Dynamics of the Thermocline: The Equatorial Undercurrent
.10
llT
no entrainment1.0
.05
-
\
with
\
entrainment
\
0.5
\
Xs
\
I
I
a .01
0
.20
.40
.60
.80
1.0
00
.20
.40
.60
.80
1.0
0
xb
- - - - - - - - ' - - - - - - - - - - ' X c
h,
0.50
b 1.0
Fig. 6.6.3. a Velocity in layer 2 on the equator with entrainment (dotted line) and without entrainment (solid line). b Depths of the two layers with (dotted lines) and without (solid lines).
c Transport of the current with and without entrainment. The difference in the transport is shown as
tl. T and is equal to the amount of fluid bled off from the undercurrent which enters the upper layer
and Samelson (1989), while retaining the fundamental elements of the model
shown schematically in Fig. 6.6.1, introduced explicit dynamics for the upper
layer. While retaining (6.4.18) as an approximation for the y momentum
equation in the upper layer, they suggested as a simple model for the x momentum equation:
(6.6.12)