Description: Conference name: North Atlantic Current (NAC) System; 19-20 April 1993, Woods Hole Oceanographic Institution, Woods Hole, MA

Description: On April 19-20, 1993 a two-day workshop was held at the Woods Hole Oceanographic Institution on "The North Atlantic Current (NAC) System". The workshop, which was sponsored by NSF/NOAA/ONR reflected a growing sense of excitement and interest in the oceanographic community in the NAC system and its role in the large scale circulation of the North Atlantic Ocean and Climate of the adjoining landmasses. The presence of the North Atlantic Current with its warm waters at such high latitudes, and its role in both the wind-driven and thermohaline circulations makes it unique amongst the Western Boundary Currents of the oceans. Being on the one hand part of the wind-driven circulation and on the other hand the upper branch of the "Global Conveyor Belt", the North Atlantic current is indeed an enigma, suggesting fundamental issues about the nature of the coupling between the two 'roles' of the current that will need to be addressed. But it was also clear from the workshop discussions that there remain considerable uncertainty about the basic structure of the NAC. A high level of interest in these questions was evident at the workshop. The lectures, presentations, and the discussion sessions where observational and modelling issues were debated, brought out many ideas for the development and focus of future research of the NAC and surrounding waters. This report is intended to provide not only a synopsis of the lectures, papers, and ideas that were discussed, but also a scientific statement from the workshop reflecting a growing consensus for initiating a coordinated research effort in the region.

Description: NSF/NOAA/ONR

Description: Also published as Journal of Marine Research, 1975, Volume 33, No . 3, pp. 355-382

Description: Twenty neutrally buoyant SOFAR floats were used in the Mid-Ocean Dynamics Experiment (MODE) to study the structure and variability of the deep ocean currents. The floats were clustered so that the pattern of motions could be resolved (mapping and pattern recognition). A number of float trajectories are shown and the very individual character of their signature is emphasized. Some floats remain nearly stationary for a year whereas others will cover hundreds of kilometers to the south or west in just a few months. Superposition of all trajectories in the spaghetti diagram is shown to reveal considerable organization of the "eddy" field in the MODE area and is thought to be caused by the near presence of the Blake-Bahama Outer Ridge to the west. There is considerable asymmetry to the float dispersal with floats rapidly scattering to the south and west, but not to the north and east even though the r .m.s. velocities are a factor 3 to 6 times greater than the mean drift. The evolution and dispersal of the float cluster is illustrated in a set of figures in each of which a 12 day segment of all float trajectories is displayed. At times their mobility and relative motion is shown to be associated with onset of sudden swirls and regions of large horizontal shear, features that are not evident from the analysis of individual trajectories. Cluster averages of the float velocities and kinetic energy, computed weekly and plotted as a function of time, show substantial variability. Much better averages are obtained by limiting the cluster to floats within a geographical region. As the spaghetti diagram indicates and the following paper discusses in more detail there exist substantial geographical variations in the average kinetic energy levels. These may be in some way caused topographically by the close proximity to the continental margin. Whatever the reason they caution us to reexamine the notion that the scale of variation of the second order eddy statistics is large compared to the eddies themselves, at least in the MODE-I area. Ten floats also contained a system to record the local pressure, temperature and vertical currents. The pressure and temperature yield data concerning low frequency vertical displacements and the vertical current meters measure the internal wave sea state which is shown to be remarkably constant.

Description: Prepared for the Office of Naval Research under Contracts N00014-66-C-0241; NR 083-004 ( WHOI), N00014-67-A-0097-001 (Yale University) and NSF Grants GX-30220 (WHOI), GX-30416 (Yale University) .