Convection Model for Hydrothermal Plumes in a Cross Flow

摘要

A primitive equation convection model is used to describe circulatory andproperty fields in a region where buoyant hydrothermal fluids discharge into a rotating stratified ocean. Model results are obtained for a line source of heat and salinity which introduces buoyancy into a steady background flow. The flow bends the hydrothermal plume over and advects it downstream, but both up and downstream of the vent there is recirculation from the plume cap to the plume stem below. This circulation draws discharge-affected water downward to be reentrained into the upwardly rising water of the plume. For the given background stratification, temperature and salinity have distinctly different anomaly patterns, with that of salinity having a dipole-like distribution. Below the temperature anomaly core of the plume, a negative salinity anomaly can occur because of this downward flux. The model is used to compare plumes having differing buoyancy inputs, here specifically differences in salt content. The effects of salinity depleted discharge are to enhance the magnitude of the salinity anomaly in the lower part of the plume and to make more vigorous buoyancy-induced vertical and horizontal flows.