Physical model of gradient zone erosion in thermohaline systems

Abstract A physical model is formulated for gradient zone erosion in thermohaline systems near equilibrium. The model includes the effects at the gradient zone boundaries of temperature modulation, caused by mildly turbulent thermals in adjacent convective zones. The equations that govern convective motion in a double-diffusive horizontal slab are solved for boundary conditions that incorporate these modulations. The result predicts microconvection disturbances within the gradient zone, with an amplitude that decays exponentially away from the boundaries. The expected thickness of observable disturbance is of the order of 1 cm, which agrees with experimental observation. Examining the solution for stability of the boundary yields, for the first time, a model of erosion behavior that agrees with an empirical correlation for boundary equilibrium.