The circulation of North Atlantic Deep Water at 16°N, 2000-2003

Abstract

The circulation of North Atlantic Deep Water (NADW) at 16°N is studied with chlorofluorocarbon (CFC) and current measurements in 2000, 2002 and 2003. The transport of the Deep Western Boundary Current (DWBC) ranges from 25.6 to 28.9 Sv in 2000 and 2002. CFC concentrations in the DWBC increased by ∼30% per year during that period. In 2003, the DWBC was weak and the main CFC increase between 2002 and 2003 occurred offshore of the DWBC. For all three repeats, a major drop in the CFC concentrations of the NADW took place at 55°W. This was also found in the distributions of salinity and oxygen. The region west of 55°W was characterized by a predomitantly southward flow. The lowest CFC concentrations were found above the Mid-Atlantic Ridge, where the zonal and meridional velocities were small and no preference of flow direction could be detected. Copyright 2004 by the American Geophysical Union.