Gulf Stream evolution through the Straits of Florida: the role of eddies and upwelling near Cuba

摘要

The meandering of the Gulf Stream through the Straits of Florida is associated with eddy activity to the north (along the Florida Keys) and the south (along the Cuban coast). This study focuses on recently identified processes along the Cuban coast, namely anticyclonic eddies (Cuban ANticyclones: CubANs) and cyclonic activity characterized by cold-core eddies (cyclones) and coastal upwelling that enhances them. It is shown that these processes are an important factor for the evolution of the Loop Current/Florida Current (LC/FC) system. In particular, the Gulf Stream meandering inside the Straits (that is manifested as the position of the FC branch) is strongly related to CubANs either inside the retracted (closer to the Cuban coast) LC branch (CubAN "A") or outside the LC as independent eddies (CubAN "B"). There are also mixed cases that both types of CubANs can be present, sharing a common place of origin, but evolving differently. These anticyclones are found to be strongly related to cyclonic activity and resulting temperature gradients along Cuba, characterized by cold-core cyclonic eddies and additional pools of cold waters that have upwelled under wind influence. These processes are shown to influence Gulf Stream meandering and also largely control the offshore export of upwelled, generally cooler and more productive, coastal waters. High-resolution simulations, in tandem with a variety of observational data, are used during a period of 8 years (2010-2017) to describe the evolution of CubANs and their contribution to Gulf Stream variability and associated coastal to offshore interactions. These findings are important for connectivity pathways between US and Cuban marine protected areas and between US coasts and the main Cuban area of oil exploration.