Numerical Models
375
Potential Vorticity ___ Streamline_·-·+ ·J
35.0
30.0
-
a. T- 22.5°C
IG
...J
25 .. 0
1.5.0
l.O.O
s.o
o.o
35.0
30.0
25.0
20.0
1.5.0
1.0.0
s.o
o.o
35.0
25.0
rt'"
40.0
4 0 . 0 -
~
f-:
.
.
. -~ -~·-·-·c. T = 15.5°C ,_
~I ·~
·-·--~~~---· ~--. .·*
-
. .!9·• .....
--4~-!'-·
./. . . ~. . - -. . -. ......-:-/
. --.
., _____ _
--~ ·:~-~
-
o.o· -
·
·
·
a.a
zo.o
~
-~---·
I\"~.
.
,_tc·.;;
l.S.Q
10.0
. .s.o
o.o
0
Long.
30
60
Fig. 6.7.5a-c. Potential vorticity (solid lines) and the streamlines (dot-dash curves with arrows) at three
levels in the Philander-Pacanowski model showing the connection between the subtropical gyre
and the equatorial circulation. Levels at 22.5, 19, and 15.5 °C, corresponding to levels above, at
and below the core of the EUC. At the level of the core flow in the subtropical gyre flows to the
equatorial region largely conserving potential vorticity and enters the EUC from both the western
boundary current and the interior. In the calculation shown the former path accounts for most of
the EUC transport. (From Liu eta!. 1994)