| Popis: |
Caribbean through-flow accounts for up to two-thirds of the Florida Current and consequently is an important conduit of heat and salt fluxes in the Atlantic branch of the Meridional Overturning Circulation (MOC). While high-latitude sinking and interior mixing processes have a first order control on the magnitude of the MOC, low-latitude wind-driven processes determine and modify the subsurface density structure of the water masses flowing through the Caribbean Sea. Considering there is evidence that up to one-half of the Florida Current originates as South Atlantic Waters (SAW), determining the distribution of SAW throughout the Caribbean Island passages is important as this constitutes the major pathway for cross-equatorial MOC return flow. Ship-based observations in the 1990’s revealed the Windward Island passages as a dominant SAW inflow pathway. However, there is still a significant amount of SAW that is taking an unknown, alternate route northward. The Anegada Passage (AP) is a major location for subtropical gyre inflow and suggested to be an alternate SAW inflow pathway. Here, we present the first co-located observations of temperature, salinity, and subsurface velocity in the AP in nearly 20 years. These observations provide evidence that the total transport (4-5 Sv) and the transport of SAW through the AP (1-2.55 Sv) is larger than previously estimated. This result implies that the AP is a significant pathway for cross-equatorial MOC return flow. The results presented here also provide evidence that gliders with acoustic doppler profilers are viable, cost-effective method for measuring island passage transport. |
