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Abstract. One hundred isopycnal floats were tracked on the 27.2 and 27.5 o-0 surfaces in the Newfoundland Basin (NFB) from July 1993 to July 1995 to study the current structure and exchanges of waters between the subtropical and subpolar gyres. The float-mapped mean flow consists of weak flows in the NFB and a strong boundary current (the North Atlantic Current (NAC)), which separates from the boundary at the Northwest Corner, becoming a diffusive zonal drift. The NAC meanders are linked to topography and have similar patterns on the two isopycnals despite the fact that the upper layer velocities are twice as fast as the lower layer ones. Perturbation velocity from the mean is used to compute isopycnal turbulent dispersion and diffusivity. This large data set allows us to

Abstract.The continually leak from the current into the Slope Sea. These observations point to a thermohaline rather than winddriven mechanism for governing the path of the Gulf Stream after it leaves the coast.

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In recent years, several studies have identified an area of intense anticyclonic activity about 500 km straight west of the Lofoten Islands at 70°N in the northern Norwegian Sea. Now recognized as the coherent Lofoten Basin Eddy (LBE), it is maintained by a supply of anticyclonic eddies that break away from the Norwegian Atlantic Current. Here we show from ship‐based surveys of its velocity field that it is quite stable with a central core in solid body rotation ∼1000 m deep, ∼8 km radius, and a relative vorticity close to its theoretical limit –f. The surveys also show the LBE typically has a >60 km radius with maximum swirl velocities at 17–20 km radius. From the velocity field, we estimate the dynamic height amplitude at the surface to be about ∼0.21 ± 0.03 dyn. m. Second, altimetry from the last 20 years shows the extremum in sea surface height relative to the surrounding waters to be about the same, 0.2 dyn. m. Third, a float trapped in the LBE for many months reveals a clear cyclonic wandering of the eddy over the deepest parts of the basin. Last, three hydrographic sections from the 1960s show the dynamic height signal to be virtually the same then as it is now. From these observations, we conclude that the LBE is a permanent feature of the Nordic Seas and plays a central role in maintaining the pool of warm water in the western Lofoten Basin.

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Neutrally buoyant floats, deployed across the northern slope of the Iceland‐Faroe Ridge at 800m depth, reveal tight topographic control of their movement: a cluster of 22 floats drifts southeast to the Faroe‐Shetland Channel where it bifurcates such that floats deployed over the upper slope turn south and eventually exit the Norwegian Sea through the Faroe Bank Channel, and floats over the deeper slope turn north in the Norwegian Sea. A subset of the latter group moves quickly north along the western slope of the Vøring Plateau and divides with most of the floats turning east into the Lofoten Basin and the remainder circulating cyclonically around the Norwegian Basin. This study establishes that i) the Faroe Bank Channel overflow waters must come from along the slope north of the Faroes, not the interior of the Norwegian Sea, and ii) exchange of intermediate waters between basins takes place along topographically controlled routes.