SUMMER MEAN CIRCULATION OF THE NORTHWESTERN ATLANTIC-OCEAN

The Mellor et al. (1982) method is applied to a new high-resolution an alysis of the temperature and salinity fields in order to determine th e summer transport and circulation of the northwestern Atlantic Ocean. This high-resolution analysis is carried out using an objective analy sis scheme which is a modification of that used by Levitus (1982). In view of the strong topographic control exhibited by the circulation fe atures in the area (i.e., the shelf break Labrador and Greenland curre nts), the scheme preferentially searches for data along, rather than a cross, isobaths. The horizontal resolution is 1/3 degrees by 1/3 degre es, with 37 vertical levels. The data were obtained from the Marine En vironment Data Service archived data and was supplemented by a subset of the National Oceanographic Data Center data from J. Reid and by add itional data for the 1980s from Fukumori and Wunsch (1991). Summer mea n transports of 49 and 46 Sv are found in the Labrador Sea and the Irm inger Sea, respectively. Most of the transport through the region is d etermined by the transport through the eastern boundary, emphasizing t he importance of the eastern Atlantic for determining the circulation in the west. The local wind stress forcing plays a relatively unimport ant role in driving the transport in the northwestern Atlantic Ocean. The current Structure is obtained by combining the results from the Me llor et al. (1982) method together with a level of no motion (at the b ottom) calculation. Using these two methods, the bottom currents are e valuated, and hence the current structure for the whole domain is dete rmined. The results show that the bottom currents follow the planetary potential vorticity (f/H) lines closely. The strongest currents are f ound along the shelf breaks, offshore from the coasts of Greenland and Labrador. The results also indicate the presence of cross-shelf flow on the western side of the Labrador Sea. The cross-shelf transport (si milar to 5 Sv) of fresh shelf waters may well be important in modifyin g the salinity characteristics, and hence convective properties, of th e central Labrador Sea.