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is illustrated by the density front formed by the Kuroshio above the peak of
the sharp (lip) topography at the shelfbreak in Fig. 1a. Since the lip
topography is only a few grid points wide, this topography and the
associated front is best represented in U coordinates.
Figure 1. Upper 400 meters north-south velocity cross-section along 124.5°E in the East
China and Yellow Seas: (a) Fall; (b) Spring.
The algorithm that maintains the hybrid vertical coordinates is T/S
conservative and monotonicity-preserving (i.e., no new T/S extrema during
re-gridding). It is referred to as the “grid generator” (Bleck, 2002) and is the
final algorithm executed during each model time step. The grid generator
relocates vertical interfaces to restore isopycnic conditions in the ocean
interior to the greatest extent possible while enforcing the minimum
thickness requirements. The minimum thickness is enforced by a “cushion”
function (Bleck, 2002) that produces a smooth transition from the isopycnic
to the p-domain. The grid generator first attempts to restore the density of a
given layer to its isopycnic reference density if necessary. If a layer is less