Assessing Tropical Cyclone Interannual Variability in the Western North Pacific Using Average Accumulated Cyclone Energy (AACE)

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The accurate quantification of tropical cyclone (TC) activity in the western North Pacific (WNP) requires a robust metric able to capture frequency and intensity variation. This study uses average accumulated cyclone energy (AACE) to assess TC variability under extreme scenarios and El Niño–Southern Oscillation (ENSO) phases. AACE measures interannual variability more comprehensively than traditional metrics by incorporating the average annual intensity contributions of TCs. In this study, AACE effectively captured ENSO-driven shifts, revealing TC energy concentration in the eastern and western WNP during El Niño and La Niña years, respectively. Additionally, AACE is less influenced by annual variations in TC frequency while preserving the contributions of both strong and weak storms. Its ability to capture spatial and intensity variations makes it a valuable metric for analyzing TC variability. These findings highlight the advantages of AACE for climate projections and risk assessments, offering novel insights into the ENSO-driven modulation of TC activity in the WNP.