[A-OS16] Physical, biogeochemical, and ecological processes and variability in the Indian Ocean

[AOS16-P01] On Long-lived Cyclonic Eddies Off Western Australia: from Statistics to Energy Analysis

*Peien Xu¹、Zhendong Hu²、Zhiyu Liu²、Tomoki Tozuka¹、Tangdong Qu³ (1.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo、2.State Key Laboratory of Marine Environmental Science, and Department of Physical Oceanography, College of Ocean and Earth Sciences, Xiamen University、3.Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles)

キーワード：Eddies and mesoscale processes, Eddy longevity, Indian Ocean, Eastern boundary currents, Energy budgets

Mesoscale eddies are crucial in ocean circulation, influencing mixing, mass transport, and the energy cascade. Long-lived eddies have drawn increasing attention due to their role in heat and energy redistribution. This study identifies the western coast of Australia as a hotspot for long-lived cyclonic eddies (LLCEs) with lifespans ≧ 365 days. Statistical comparisons reveal their distinctiveness compared to LLCEs in other regions and shorter-lived eddies locally. LLCEs off western Australia exhibit unique features such as larger amplitudes and higher eddy kinetic energy. Energy budget analysis links their longevity to energy extraction from eddy potential energy and background flow, particularly during their generation phase. Positive vertical eddy density flux and barotropic energy conversion sustain their structure and longevity. This research underscores the uniqueness of LLCEs off western Australia, elucidating their longevity mechanisms and contributing to the broader understanding of global long-lived eddies.