Computations of the eddy heat and density transports across the Gulf Stream

Abstract

Data of the current velocity, temperature and density of the Gulf Stream, collected during 200 crossings of the current in cruises off Onslow Bay, Jacksonville (30° N) and Cape Hatteras, are used to compute the eddy fluxes of heat and density across the mean current. In each cruise an eddy transport of heat is observed, which is directed from the colder coastal water to the Sargasso Sea in the surface layers. The meanders in the stream appear to increase the thermal contrast across the so-called Gulf Stream front and thus violate the ordinary diffusion laws by not transporting heat from the warm to the cold source. The transport of density across the stream is, in general, towards the shore, reflecting mostly the influence of the temperature on the density.

Webster (1961 b) has shown in an earlier study that there is a surface flow of kinetic energy and momentum from the meanders to the mean flow of the Gulf Stream. Since the meanders of the scale considered in these studies appear to speed up the Gulf Stream and do not feed upon, but actually build up the thermal contrast near the surface, these eddies must be forced.

More measurements of the kind described in this paper, are needed to verify the observed abnormal heat and density fluxes in the Gulf Stream.