Measurements of eddy fluxes of momentum in the surface layer of the Gulf Stream

Abstract

Further observations are reported, in which the action of eddies in the Florida Current produces a surface flux of momentum towards higher mean velocities. The results are thus in contrast to what would be expected if the eddies acted as a frictional dissipation mechanism. Furthermore, associated with the momentum flux is a surface transfer of kinetic energy from the eddies to the mean flow. The results from four locations along the length of the Florida Current are compared. The kinetic energy transfer between fluctuations and mean flow is found to be similar in magnitude at all locations and is restricted primarily to the zone of cyclonic shear of the mean surface velocity field. The flow of kinetic energy to the mean flow is sufficient to maintain the current against the dissipative actions of lateral eddy processes. Both the techniques used to measure surface velocities and the sampling method are examined. Neither appears to introduce any biases which might account for the observed momentum fluxes.