Using satellite observations and eddy-resolving reanalysis data, the three-dimensional energetics evolution of a typical cyclonic eddy (CE1) was investigated during its interaction with four typhoons and the Kuroshio Current (KC) east of the Luzon-Taiwan Islands from June to September 2004. Four typhoons Mindulle (TY1), Rananim (TY2), Aere (TY3) and Haima (TY4) passed by CE1 successively with minimum distances of ~35 km, ~370 km, ~256 km and ~77 km, respectively. The CE1 underwent anomalously complicated deformation during the ~80-day interaction, with all the eddy energy reservoirs and energy conversions exhibiting complex spatial-temporal variations. During eddy-KC interaction under normal winds, the CE1 obtained kinetic energy (KE) via mixed barotropic and baroclinic instabilities. When typhoons passed, it acquired considerable KE from the strong winds while releasing KE to the mean flow. During the passage of TY2, baroclinic instability also enabled the eddy to gain KE through the conversion of eddy available potential energy (EPE) to eddy kinetic energy (EKE). During TY1, TY3 and TY4, however, pronounced upwelling was induced in the eddy area, leading to inverse baroclinic conversion from EKE to EPE. The results indicate that typhoons could enhance the cyclonic eddy in two ways: directly generating EKE through eddy wind work and indirectly triggering inverse baroclinic energy conversion from EKE to EPE when approaching sufficiently close to the eddy. This work elucidates the impacts of typhoons on cyclonic eddies in the western boundary current region, providing a basis for understanding their long-term cumulative effects on ocean circulation and climate.

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