Flow, hydrography, turbulent mixing, and dissipation at Fieberling Guyot examined with a primitive equation model

The extensive set of measurements previously taken at Fieberling Guyot provides a backdrop for model results on flow, hydrography, turbulent mixing, and derivative variables. A z ‐level primitive equation model driven at subinertial and superinertial tidal frequencies allows the nonlinear interaction of free and topographically trapped motions to jointly determine model outcomes. Model residual flows, mean hydrographic features, topographic amplification of oscillatory currents, turbulent dissipation (ɛ) and vertical diffusivity ( K V ) profiles are all examined in the light of the observations. Azimuthal residual flows are toroidal above the summit with maximum speed ∼20 cm s −1 . Diurnal flow over the summit is intensified by a factor >20. Downward vertical flow as a time‐mean (〈 w 〉 t ) occurs from ∼150 m above the summit apex to summit rim depth, with radially inward flow above the apex and radial outward flow below. Upward 〈 w 〉 t rings the summit at larger r . The existence of the observed cold dome is shown to depend on 〈 w 〉 t in the summit circulation cell. Vertical current shear is concentrated in a 150 m thick cap above the summit, accounting for a domed distribution of ɛ and K V with maxima of ∼10 −7 W kg −1 and ∼30 cm 2 s −1 , respectively. Profiles most like the observations of K V are obtained with a subgrid‐scale parameterization in which the turbulent Prandtl number (Pr) depends on the shear Richardson number (Ri).