We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Generation of Vorticity Near Topography: Anticyclones in the Caribbean Sea.
- Authors
van der Boog, C. G.; Molemaker, M. J.; Dijkstra, H. A.; Pietrzak, J. D.; Katsman, C. A.
- Abstract
Mesoscale anticyclonic eddies dominate the sea‐surface height variability in the Caribbean Sea. Although it is well established that these anticyclones are formed near the eastern boundary of the Caribbean Sea, which is demarcated by the Lesser Antilles, the source of their anticyclonic vorticity remains unclear. To gain insight into this source, we analyze the fluxes of vorticity into the Caribbean at its eastern boundary using a high‐resolution numerical model. We find that the anticyclonic vorticity in the eastern Caribbean Sea predominantly originates from regions where intense ocean currents flow close to the Lesser Antilles. More specifically, St. Lucia and Grenada are hotspots for vorticity generation. The local generation rate scales with the amplitude of the volume transport through the passages between these islands. This finding is in contrast with the view that anticyclonic North Brazil Current (NBC) rings in the Atlantic Ocean are the main source of anticyclonic vorticity in the eastern Caribbean Sea. Our analyses reveal that the direct contribution of the vorticity of the NBC rings is of lesser importance than the local generation. However, the collision of upstream NBC rings with the Lesser Antilles increases the volume transport through the passages into the Caribbean Sea, so that their presence indirectly leads to enhanced local production of anticyclonic vorticity. This process is an example of the importance of vorticity generation near topography, which is ubiquitous in the oceans, and expected to be important whenever currents and steep topography meet. Plain Language Summary: The surface variability in the Caribbean Sea is dominated by bodies of water that rotate in clockwise direction, referred to as anticyclonic eddies. These eddies form in the eastern part of the basin westward of the steep topography of the Lesser Antilles island arc. Because it is unclear what the source for their vorticity (i.e., what determines the tendency of the water to rotate) is, we analyze the fluxes of vorticity into the eastern Caribbean Sea. We use a numerical model with a high spatial resolution to show that two thirds of the vorticity flux is generated locally near the topography of the islands. Furthermore, the magnitude of the locally generated vorticity scales with the magnitude of the transport between the islands. In turn, this transport is regulated by the presence of anticyclonic North Brazil Current rings that collide with the Lesser Antilles. This implies that, while the direct contribution of the vorticity influx of the North Brazil Current rings is at most one third of the anticyclonic vorticity flux into the Caribbean Sea, these rings predominantly impact the vorticity influx into the Caribbean indirectly. These results highlight the importance of vorticity generation near topography for the total vorticity budget, which is expected to be important whenever currents and steep topography meet. Key Points: The vorticity flux into the Caribbean Sea is dominated by the local generation of vorticity near the topography of the Lesser AntillesNorth Brazil Current rings trigger local vorticity generation through increased transport, while their direct vorticity influx is limitedThis high‐resolution model example suggests that vorticity generation near topography can be a significant factor in the global budget
- Subjects
LESSER Antilles; VORTEX motion; NBC Television Network; ANTICYCLONES; ISLAND arcs; TOPOGRAPHY; MESOSCALE eddies; OCEAN currents
- Publication
Journal of Geophysical Research. Oceans, 2022, Vol 127, Issue 8, p1
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2021JC017987