306
a) characteristic pat/1
90
d)
g)
Buoyancy Forced Circulation and Cross-Gyre Flow
Western regime
b) regimes
===--~ .. '-----------1 20°
c) total transport
one interface
e)
f)
Fig. 5.3.5a--g. Results of the calculation of Luyten and Stommel (1986b) for the subtropical gyre.
The gyre is driven by a distribution of Ekman pumping and cross-isopycnal fluxes, each a function
only oflatitude. g The depth of the lower layer on the eastern boundary is ISO m, and y1 = I crnls 2 •
The width of the basin is 2000 km, and the midlatitude of the basin is at 30°N, where the outcrop
line is placed. The maximum amplitude of each forcing velocity is 3 cmjs and of course the Ekman
pumping velocity is negative. a Characteristic curves of the solution. b Western and eastern domains of the solution as determined by the critical characteristic emanating from the intersection of
the outcrop line and the eastern boundary. c Sverdrup transport streamlines. d Depth contours (in
meters) of the upper layer. e Contours of h + r 12h1 which are the streamlines of the upper layer
flow. f The contours of h which yield the streamlines of the lower layer flow