Upper Ocean Transport in the Anegada Passage From Multi‐Year Glider Surveys

Abstract

Caribbean through‐flow accounts for two‐thirds of the Florida Current and consequently is an important conduit of heat and salt fluxes in the upper limb of the Atlantic Meridional Overturning Circulation (AMOC). Considering there is evidence that up to one‐half of the Florida Current originates as South Atlantic Water (SAW), determining the distribution of SAW throughout the Caribbean Island passages is important as this constitutes the major pathway for cross‐equatorial AMOC return flow. The Anegada Passage (AP) is a major pathway for subtropical gyre inflow and suggested to be a potential SAW inflow pathway worth revisiting. Here, we present glider‐based observations of temperature, salinity and subsurface velocity that represent the first observations of any type in the AP in nearly 20 years. An isopycnal water mass analysis is conducted to quantify the transport of water masses with South Atlantic or North Atlantic origin. Two potentially new aspects of AP transport are revealed. The total AP transport (−4.8 Sv) is shown to be larger than previously estimated, potentially by up to a factor of two. The transport of SAW through the AP (−1.66 Sv) is also shown to be larger than previously estimated, which represents 35% of the total transport reported here and 28% of the SAW entering the Caribbean north of the Windward Island Passages. These results indicate the AP may be an important pathway for cross‐equatorial AMOC return flow. These results also provide evidence that gliders with acoustic doppler profilers are a viable method for measuring island passage transport.