Study Explains How Large Rotating Currents Near Cuba Influence the Gulf Stream
– APRIL 10, 2019
Researchers described, for the first time, the dynamics and interactions of regional ocean flows with both anticyclonic eddies (circulating clockwise) near Cuba’s northern coast (dubbed “CubANs”) and cyclonic eddies (circulating counter-clockwise) along Florida’s southern coast. The new findings relate to ocean circulation beyond the Cuba and South Florida coasts as they are connected to the Gulf Stream system, which manifests as the Loop Current in the Gulf of Mexico and as the Florida Current in the Straits of Florida. The Gulf Stream controls the connectivity between the Caribbean Sea and the Atlantic Ocean and is a component of the Atlantic Meridional Overturning Circulation, which plays a key role in the global climate regulation and evolution. These processes are important globally and regionally, with implications for socioeconomic issues associated with south Florida fisheries and tourism.
The scientists published their findings in the Journal of Geophysical Research: Oceans: The Dynamics of Cuba Anticyclones (CubANs) and Interaction with the Loop Current/Florida Current System.
“Cuba and south Florida are separated, but also connected by the Gulf Stream,” explained study author Villy Kourafalou. “As they are at either side of the Florida Straits, Cuba and south Florida experience very strong currents flowing from west to east, the well-known Florida Current component of the Gulf Stream. The meandering of the Florida Current is very important since any major change in the current’s orientation influences the flow of these strong, warm currents and impacts many things that are affected by it, such as navigation, pathways of fish larvae, and pollutants (such as a potential oil spill in Cuban waters).”
The research team identified the development and evolution of the mesoscale anticyclonic CubAN eddies along the northwestern Cuba during a ~13-year period (2004–2016) using high-resolution, hydrodynamic simulations and observations collected via satellite (temperature, altimetry, ocean color), in situ Global Drifter Program drifters, and Acoustic Doppler Current Profiler buoys.
The authors demonstrated a synergy between the overall evolution of the Loop Current-Florida Current system and CubANs, which were associated with periods of detachment from the Loop Current. As the CubANs separated from the Loop Current, they helped to push the Florida Current northward and contributed to its meandering behavior, with it sometimes moving toward south Florida and the Florida Keys and sometimes toward Cuba.
The Florida Current was influenced by cyclonic frontal eddies along south Florida and the Florida Keys and CubAN anticyclonic eddies along the Cuban coast. An increased mixed layer and weaker upper ocean stratification related to the CubANs’ eastward evolution along the Straits. The team tracked mean sea surface temperature in the Florida Straits during model simulations and found that they increased (more than a half degree) and coincided with prolonged periods of warm CubANs. In combination with adjacent cooler waters due to wind-induced coastal upwelling and cold-core cyclonic eddies, strong temperature gradients formed over northern Cuba waters, which may have substantial effects on reefs and Marine Protected Areas.
“A major breakthrough of this study is that phenomena near Cuba and at the entrance of the Straits of Florida in the southern Gulf of Mexico can impact the evolution of the Loop Current within the full Gulf basin and, thus, the overall evolution of the Gulf Stream,” said Kourafalou. “The findings of the study have important implications for ocean prediction by improving the models that predict ocean circulation and impacts of storms in this sub-tropical environment.”
The authors are currently working on further analyses of the dynamical mechanisms controlling the formation and evolution of CubANs as new observations become available and longer-term studies to further associate CubANs with the overall variability of Loop Current, Florida Current, and Gulf Stream modulations.
Data are publicly available through the Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC) at doi:10.7266/N7833QKC.
The study’s authors are Vassiliki Kourafalou, Yannis Androulidakis, Matthieu LeHenaff, and HeeSook Kang.
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This research was made possible in part by a grant from the Gulf of Mexico Research Initiative (GoMRI) to the Rosenstiel School of Marine and Atmospheric Science and the Cooperative Institute for Marine and Atmospheric Studies at the University of Miami for their project Influence of river induced fronts on hydrocarbon transport. Other funding sources included the National Oceanic and Atmospheric Administration (NOAA) RESTORE Act Science Program (NA15NOS4510226) and NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML).
The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit https://gulfresearchinitiative.org/.
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