A quasi‐synoptic survey of the thermocline circulation and water mass distribution within the Canary Basin

Abstract

Shipboard hydrographic measurements and moored current meters are used to infer both the largescale and mesoscale water mass distribution and features of the general circulation in the Canary Basin. We ~ound a convoluted current system dominated by the time-dependent meandering of the eastward ßo\nng Azores Cu~rent. and the fo rmatio n of mesoscale eddies. At middepths, several distinctly different water masses are 1denttfied: Subpolar Mode and Labrador Sea Water are centered in the northwesl, Subantarctic Intermediate Water is centered in the southeast, and the saltier, warmer Mediterranean tongue lies between them. ~esos~le structures of these water masses suggest the presence of middepth meanders and detached edd1es wh1ch may be caused by ßuctuations of the Azores Current.

Water masses, circulation and transport in the eastern boundary current of the North Atlantic subtropical gyre

“…According to Stramma (1984), most of the inflow of 11 x 10 6 kg s -1 turns to the south in the central east Atlantic, but a small amount (4-5 x 10 6 kg s -1 ) reaches the near coastal region and feeds the Canary Current. Similarly, Käse et al (1986) ). On the eastern side of both sections, a weak southward current of approximately 1 cm s -1 is observed.…”

“…2a). This MW is described as warm and salty water in the lower thermocline, as seen in the middle and lower panels of Figures 4 and 5 (Worthington, 1976;Käse et al, 1986;Reid, 1994;Arhan et al, 1994). Deeper than the MW, North Atlantic Deep Water (NADW) is detected in the transect GC-F, the only one deep enough to allow for the existence of this water mass.…”

A view of the Canary Basin thermocline circulation in winter

“…The vertical orientation of selected isohalines below 600 m indicates two strong internal fronts which both have expression in the Canary basin, interpreted by Käse et al [1986] as Labrador Sea Water (LSW).…”

“…North of Madeira, AC 1 branches southward and northward. The northward branch of AC 1 has already been de cribed by Käse et al [ 1986]. They suspect tha t a part of thi current retums to the south via the Portugal Current.…”

SOFAR float Mediterranean outflow experiment : summary and data from 1986-88

“…Data from the first two years has been processed and described in Armi et al, 1988;Armi et al, 1989;Käse et al, 1986;Price et al, 1986;Richardson et al, 1989;Schmitz et al, 1988;Tarbell et al, 1987;and Zemanovic et al, 1988.…”