An investigation of the link between lead-induced thermohaline convection and arctic eddies

A recent laboratory study indicates that a turbulent buoyant line plume dis charging into a rotating stratified fluid provides a natural mechanism for generating a series of anticyclonic geostrophic vortices [Bush and Woods 19 99]. Here we examine the implications of these experimental results in the context of the thermohaline convection which develops when saline water is released as leads freeze over in the polar oceans. Using the experimental r esults in conjunction with a simple numerical model of plume dynamics in a non-uniformly stratified environment, we develop a model which characterize s the geometry of the eddies which would develop owing to lead-induced conv ection. The model predicts that, in the absence of strong currents, lead-in duced thermohaline convection may generate anticyclonic geostrophic vortice s of characteristic radius 2-10 km at the base of the mixed layer; however, this mechanism cannot account for the arctic eddies observed at substantia l depths beneath the mixed layer, cyclonic, or strongly ageostrophic eddies .