Study on the influence of island chains on the vortex splitting of mesoscale eddies

Abstract

In the ocean, there exist multi-scale water movements, among which mesoscale eddies are important carriers of oceanic material and energy transport. These vortices contain substantial kinetic energy and heat, playing a pivotal role in oceanic mass and energy transfer. The presence of islands can alter the movement path, intensity, and structure of vortices, and may even lead to vortex splitting. Vortex-island interactions not only affect local oceanic dynamic conditions but may also have broader impacts on large-scale ocean circulation and material transport. Previous multi-island studies have primarily focused on the range where the ratio of island spacing to mesoscale vortex diameter falls between 0.1 and 0.4. However, in real oceanic environments, cases where this ratio exceeds 0.4 are more common, particularly in multi-island regions such as the Lesser Antilles, where the ratio often reaches 0.6 or higher. To gain a more comprehensive understanding of the interaction mechanisms between island spacing and mesoscale vortices, as well as their dynamic processes across a broader range of ratios, this study employs the Regional Ocean Modeling System to conduct idealized numerical experiments. By varying parameters related to island configurations, we analyze the influence of islands on vortex trajectory and structural evolution, extending the investigation to cases with ratios ranging from 0.13 to 0.67. Based on the numerical simulation results, we propose a dimensionless function y that integrates three island-related variables, characterizing the impact of different island parameters on vortex splitting during vortex-island interactions.