Mechanisms of the 40–70 Day Variability in the Yucatan Channel Volume Transport

The Yucatan Channel connects the Caribbean Sea with the Gulf of Mexico and is the mainoutflow region of the Caribbean Sea. Moorings in the Yucatan Channel show high-frequent variability inkinetic energy (50–100 days) and transport (20–40 days), but the physical mechanisms controlling thisvariability are poorly understood. In this study, we show that the short-term variability in the YucatanChannel transport has an upstream origin and arises from processes in the North Brazil Current. To establishthis connection, we use data from altimetry and model output from several high resolution global models.A significant 40–70 day variability is found in the sea surface height in the North Brazil Current retroflectionregion with a propagation toward the Lesser Antilles. The frequency of variability is generated by intrinsicprocesses associated with the shedding of eddies, rather than by atmospheric forcing. This sea surfaceheight variability is able to pass the Lesser Antilles, it propagates westward with the background ocean flowin the Caribbean Sea and finally affects the variability in the Yucatan Channel volume transport.