Investigating the anticyclonic eddy merger process in southeastern Gulf of Mexico using altimeter and drifting buoy

Yuan Zhonghao; Zhu Mingming; Wang Jianping; Han Kaili; Luan Chunlei; Wei Zhenhua

doi:10.12284/hyxb2023154

Volume 45 Issue 11

Nov. 2023

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Yuan Zhonghao，Zhu Mingming，Wang Jianping, et al. Investigating the anticyclonic eddy merger process in southeastern Gulf of Mexico using altimeter and drifting buoy[J]. Haiyang Xuebao，2023, 45(11)：10–19 doi: 10.12284/hyxb2023154

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Investigating the anticyclonic eddy merger process in southeastern Gulf of Mexico using altimeter and drifting buoy

doi: 10.12284/hyxb2023154

Shandong Provincial Key Laboratory of Restoration for Marine Ecology, Shandong Marine Resource and Environment Research Institute, Yantai 264006, China

Received Date: 2023-04-06
Rev Recd Date: 2023-07-25

Available Online: 2023-10-31

Publish Date: 2023-11-30

Abstract

Abstract

Combining satellite altimetry and drifter data, the method of sea surface height to discover and track an anticyclonic eddy merger event that occurred near the southeastern Gulf of Mexico was used in this study. By studying this typical anticyclonic eddy merger process, the mode of eddy merging is preliminarily revealed, which helps to further understand the complex eddy mechanism. The Eulerian eddy results show that pairs of anticyclonic eddies attract each other and propagate together for more than three weeks before merging into a unified eddy structure and continuing to propagate westward. The Lagrangian vortex trajectories captured by drifters provide evidence of water exchange between the vortices before the merger, as one drifter exchanged its original anticyclonic eddy on November 15, indicating significant water exchange between the vortices before being observed by the altimeter. Before and after the merger, the radii of the Eulerian and Lagrangian vortices both increased significantly with the Eulerian radius improving by 96.2% and the Lagrangian radius of the drifting buoys pulled by two anticyclonic eddies improving by 49.1% and 115.6%, respectively. The sea surface temperature field also exhibited different environmental responses due to the merging effect, further verifying the occurrence of the merger process. Finally, the analysis of the dynamic evolution of kinematics such as kinetic energy, vorticity, and divergence before and after the merger, as well as the morphological changes such as radius, amplitude, and shape, showes that the merger roughly experienced processes such as vortex asymptote, water exchange, contour compression and deformation, elongated elliptical vortex generation, and boundary reshaping. The vertical structure of the plane where the vortex is located mainly shows evolution from bimodal to unimodal. After the vortex merger, energy is transferred to the mesoscale through inverse cascade. Due to the single-core vortex structure, some statistical properties are biased during the merging process, which may have led to abrupt changes before and after the event.
- anticyclonic eddy,
- eddy merger,
- satellite altimetry,
- drifting buoy

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References(31)

References

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