a
b
60"N
summer
,- ........ ~ . .
. .
...
......... .
SO"N
40"N
30"N
20"N
10"N
Fig. 3.11.4a,b. As in the previous figure for ao = 26.5. (From Lozier et al. 1996). a Depth of the
density surface. b Potential vorticity on the same surface