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artefact due to improper boundary conditions imposed on the horiwntal velocity (Deleersnijder,
1992). In the region of the Anadyr Strait, close to the Siberian coast, the upwelling velocity is
directed upwards and can be as high as 10 m day-I. Thus, the upwelling velocity is large
enough to bring the thermocline, initially located at z = - 15 m, up to the surface.
EXTR. UPWEWNO VELOCITY
+ : .... lI'W.J it: lxlO ·' m'"
_ ; "'uw .. ~-lxIO ·' m "I
Figure 11 . Representation of the upwelling velocity. For each water column, one takes into
account the extremum of the upwelling velocity, wUW,E' i .e., the value of wuw that has the
maximum absolute value. The verticals where wUW,E ~ 2xlO- 5 m S-1 (wUW,E ~ 2xlO- 5 m s-l)
are identified by "+" ("-").
As previously stated, the wind forcing is not the main cause of the vertical motions. It
follows that one has to look for another upwelling mechanism. Inspiration can be found in the
Ekman pumping theory set out in classical treatises of geophysical fluid mechanics (e .g .•
Cushman-Roisin, 1994).
It may be seen that