Mechanisms of Cyclonic Meander Formation in the Western Yucatan Channel

Abstract

Cyclonic meanders in the western Yucatan Channel generate intense frontal conditions associated with strong isopycnal uplift, enhanced vertical shear, and local transformation of Caribbean waters into Yucatan Gulf Common Water. Observational composites further show that strong meander events are consistently preceded by anticyclonic circulation in the northwestern Caribbean, suggesting an upstream mesoscale influence. Here, we test whether Caribbean anticyclones can promote western-channel meander development using a fully nonlinear, two-active-layer shallow-water model. A composite extended, non-meandering Loop Current provides the reference state, while otherwise identical experiments are initialized with Caribbean anticyclones of increasing amplitude. In the control experiment, no sustained western-channel cyclonic meander develops over 30 days. In contrast, the injected anticyclones progressively deform the Yucatan Current and promote the development of a coherent cyclonic meander within approximately 25 days. The cyclonic response strengthens systematically with anticyclone amplitude. Regional diagnostics over the western Yucatan Channel show increasing cyclonic vorticity, enhanced positive barotropic energy conversion, and rapid late-stage eddy kinetic energy growth during meander amplification. These results support a dynamical pathway in which upstream Caribbean anticyclones initiate the perturbation, while local Yucatan Current dynamics contribute to its subsequent amplification. Future work will quantify the vorticity source and assess barotropic and baroclinic energy pathways across different Loop Current states. Cyclonic meanders in the western Yucatan Channel generate intense frontal conditions associated with strong isopycnal uplift, enhanced vertical shear, and local transformation of Caribbean waters into Yucatan Gulf Common Water. Observational composites further show that strong meander events are consistently preceded by anticyclonic circulation in the northwestern Caribbean, suggesting an upstream mesoscale influence. Here, we test whether Caribbean anticyclones can promote western-channel meander development using a fully nonlinear, two-active-layer shallow-water model. A composite extended, non-meandering Loop Current provides the reference state, while otherwise identical experiments are initialized with Caribbean anticyclones of increasing amplitude. In the control experiment, no sustained western-channel cyclonic meander develops over 30 days. In contrast, the injected anticyclones progressively deform the Yucatan Current and promote the development of a coherent cyclonic meander within approximately 25 days. The cyclonic response strengthens systematically with anticyclone amplitude. Regional diagnostics over the western Yucatan Channel show increasing cyclonic vorticity, enhanced positive barotropic energy conversion, and rapid late-stage eddy kinetic energy growth during meander amplification. These results support a dynamical pathway in which upstream Caribbean anticyclones initiate the perturbation, while local Yucatan Current dynamics contribute to its subsequent amplification. Future work will quantify the vorticity source and assess barotropic and baroclinic energy pathways across different Loop Current states.