9529606 McCartney In this project PIs from Woods Hole and Scripps will carry out hydrographic cruises enclosing a large portion of the North Atlantic Sub Polar Gyre (SPG) between Greenland and the Azores. The hydrography will form the base of a much larger study of the circulation of the SPG, in which autonomous, subsurface floats will monitor both subsurface currents and the upper layer temperature and salinity structure over a two-year period. The first section will be occupied during the fall of 1996, in which floats will be deployed, and currents will be monitored using shipboard Acoustic Doppler Current Profilers. The second section will be occupied in the Spring of 1997, and will include a full suite of chemical tracers to assess the effects of winter time mixing. The principal goals are to study the transformation of the thick upper layer of relatively warm water over the course of the winter, to describe how that transformation is embedded in the general circulation of the North Atlantic Current and SPG, and to examine the branching of eastward flowing subtropical water from the North Atlantic Current into the SPG. Attention will also be paid to entrainment of upper and intermediate waters into deep overflows, the recirculation of intermediate and deep waters in the subpolar North Atlantic and the distribution of decadal changes throughout the subpolar region by comparison with historic data.
