HR: 10:50h
AN: OS52A-03    [Abstracts]
TI: Deep overflow of Atlantic waters to the Caribbean Sea through Windward Passage
AU: * Johns, W
EM: bjohns@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL , United States
AU: Johns, E
EM: libby.johns@noaa.gov
AF: NOAA Atlantic Oceanographic and Meteorological Laboratories, Miami, FL , United States
AU: Smith, R
EM: ryan.smith@noaa.gov
AF: NOAA Atlantic Oceanographic and Meteorological Laboratories, Miami, FL , United States
AU: Molina, J
EM: jmolina@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL , United States
AB: From October 2003 to February 2005 a field experiment was conducted in the Windward Passage to determine the mean flow structure in the passage and its variability on time scales from tidal to seasonal. The study included measurements of the deep inflow of North Atlantic Deep Water over the ~1670 m sill in Windward Passage. These are the first direct measurements of this deep inflow, which represents one of only two pathways by which deep waters of the Caribbean and Gulf can be ventilated from the Atlantic (the other being the Anegada/Jungfern passage south of Puerto Rico). Current meters located at the sill recorded a persistent inflow with typical speeds of 20-40 cm/s, and only occasional interruptions. Four shipboard surveys of the passage provide an additional view of the deep overflow and its penetration into the abyssal Caribbean. Preliminary estimates of the mean deep inflow suggest a value near 0.4 Sv, which is about twice the corresponding value for the Anegada/Junfern inflow and indicates that Windward Passage in fact may be the dominant deep water source for the Caribbean. The source of the deep inflow through Windward passage is derived from a branch of the Deep Western Boundary Current (DWBC) that splits off the main path of the DWBC outside the Bahamas and filters through deep passages in the central Bahamas, a new discovery made in this program. Repeated sections made across the deep passages in the southern Bahamas show that nearly all of the upper DWBC (associated with waters formed in the Labrador Sea), is diverted through these passages to form a strong deep jet of 5-7 Sv flowing southeastward along the coasts of Cuba and Hispaniola, inside the Bahamas island arc. A small portion of this flow spills through Windward Passage before this deep jet rejoins the main path of the DWBC off Puerto Rico.
DE: 4283 Water masses
DE: 4512 Currents
DE: 4515 Deep recirculations
DE: 4553 Overflows
DE: 4576 Western boundary currents
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly