Boreal summer intraseasonal oscillation impact on western north pacific typhoons and rainfall in Taiwan

Chih Wen Hung*, Ho Jiunn Lin, Pei Ken Kao, Ming Fu Shih, Wei Yi Fong

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


This study discusses the boreal summer intraseasonal oscillation (BSISO) impact on the western North Pacific (WNP) typhoons and the summer rainfall in Taiwan. The real time BSISO1 and BISISO2 indices are created using the first two and the third and fourth principal components of the multivariate empirical orthogonal function analysis, based on outgoing longwave radiation (OLR) and zonal wind at 850 hPa from Lee et al. (2013). The results show that heavy rainfall in Taiwan and the associated WNP typhoon frequency patterns are closely related to the 10 - 30 days BSISO2 phases during the typhoon season (July - October). Taiwan has larger rainfall during BSISO2 phases 3, 4, and 5 when the major BSISO2 convection moves northwestward from the Philippine Sea to the Taiwan area. During phases 3 and 4 the anomalous low-level cyclonic flow and the increased typhoon frequency directly result in larger rainfall in Taiwan. Phase 5 exhibits enhanced low-level southwesterly flow which transports the moisture to Taiwan responsible for more summer rainfall on the island.

Original languageEnglish
Pages (from-to)893-906
Number of pages14
JournalTerrestrial, Atmospheric and Oceanic Sciences
Issue number6
Publication statusPublished - 2016 Dec


  • Boreal summer intraseasonl oscillation
  • Madden-julian oscillation
  • Taiwan
  • Typhoon

ASJC Scopus subject areas

  • Oceanography
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)


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