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6 Rotational Effects
Fig. 6.20 Illustration for the description of the geostrophic adjustment process
6.12.2 How Does It Work?
Initially, lateral pressure gradients associated with the slope of the density interface
creates bottom f ow directed radially inward (Fig. 6.21). Consequently, the sea level
will start to rise in the centre of this patch owing to the resultant fl w convergence
in the bottom layer. Pressure-gradients owing to a tilted sea level, on the other hand,
creates surface fl w directed radially outward. On time scales of the inertial period
and beyond, the Coriolis force comes into play and deflect these f ows. The initial
radial spreading turns into circular geostrophic motion. Water-column squeezing
produces a geostrophic eddy of cyclonic vorticity in the low-density surface patch.
Water-column stretching produces a clockwise rotating eddy in the ocean underneath.
Fig. 6.21 Illustration of the geostrophic adjustment process in a 2-layer ocean and resultant
geostrophic eddies for the northern hemisphere