Effect of ISO-SSE Interaction on Accelerating the TS to Severe TS Development in the WNP Since the Late 1990s

Chi Cherng Hong, Chih Hua Tsou, Ming Ying Lee, Chi Chun Chang, Huang Hsiung Hsu, Kuan Chieh Chen

Research output: Contribution to journalArticle


This study addressed the abrupt increase in the development speed of tropical storms (TSs) to severe TSs (≥ category 3, referred to as STSs) in the western North Pacific (WNP) during the late 1990s. Our investigation indicated that the TSs developed into STSs with a faster speed since the late 1990s. The eddy kinetic energy budget of synoptic-scale eddy (SSE) indicated that the enhancement of energy conversion from intraseasonal oscillation (ISO) to SSE played a critical role in accelerating the TS-to-STS development. The increase of ISO-SSE interaction was attributed to the mega La Niña–like mean state change. The anticyclone anomaly associated with mega La Niña and warm oceanic condition in the WNP substantially modified the mean TS genesis location (northwestward shift) and enhanced the ISO magnitude in the South China Sea and Philippine Sea, thereby amplifying the ISO-SSE interaction in the WNP in the late 1990s.

Original languageEnglish
Pages (from-to)12,008-12,014
JournalGeophysical Research Letters
Issue number21
Publication statusPublished - 2018 Nov 16



  • ISO-SSE interaction
  • abrupt increase
  • intraseasonal oscillation (ISO)
  • tropical storm

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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