Very large (5-10 cm s-1) long-term averaged zonal flows have been observed near 4000 m depth in the vicinity of a recently hypothesized (Worthington, in press) horizontally restricted subtropical gyre in the deep western North Atlantic. The Reynolds stresses associated with low frequency fluctuations may play a significant role in the dynamics of this deep mean flow, possibly inducing a significant downstream increase in transport of the Gulf Stream, perhaps driving the deep gyre.
Schmitz, William J.. 1977. "On the deep general circulation in the western North Atlantic." Journal of Marine Research 35, (1). https://elischolar.library.yale.edu/journal_of_marine_research/1383