INVERSIONS OF DATA FROM THE THERMOHALINE STAIRCASE IN THE WESTERN TROPICAL NORTH-ATLANTIC

Analyses of data gathered in spring and fall, 1985, in the thermohalin e staircase east of Barbados have been made with a more extensive trea tment of the tracer problem. The results of calculations with various models suggest that the minimum balance consistent with the observatio ns is between advection along the layers and through the interfaces an d vertical diffusion and that horizontal mixing is only a minor proces s in the staircase region. With positive vertical diffusion coefficien ts for salt and heat the estimations for vertical flux across the inte rfaces indicate the presence of salt-fingering. The horizontal velocit y in the fall is an order of magnitude stronger than in the spring, an d the vertical velocity, which may be related to salt-fingering, is do wnward in both seasons. It is also shown that the velocity derived fro m the tracer distributions and the one based on geostrophic balance ar e not the same. Generally speaking, the results obtained with the fall data other than the horizontal velocity are consistent with those fro m the spring data.