The Tropical Transition in the Western North Pacific : The Case of Tropical Cyclone Peipah (2007)

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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  • Minhee Chang
  • Chang-Hoi Ho
  • Johnny C. L. Chan
  • Myung-Sook Park
  • Seok-Woo Son
  • And 1 others
  • Jinwon Kim

Related Research Unit(s)


Original languageEnglish
Pages (from-to)5151-5165
Journal / PublicationJournal of Geophysical Research: Atmospheres
Issue number10
Online published16 Apr 2019
Publication statusPublished - 27 May 2019



This study examines the transition of an extratropical disturbance to a tropical cyclone (TC), Peipah (2007), in the western North Pacific (WNP), using reanalysis and geostationary satellite data. Instead of regular diurnal fluctuations of deep convection, the pre-TC disturbance accompanies deep convection only for short durations every other day. When the pre-TC vorticity is traced back to 7 days prior to its formation, the traced-back vorticity indicates a strong potential vorticity (PV) trough in the subtropical upper troposphere that originated from the midlatitude lower stratosphere. The quasi-geostrophic forcing and reduced static stability at the leading edge of the PV trough result in the formation of an extratropical disturbance. The vertical structure of the extratropical disturbance shows maximum vorticity in the upper troposphere and cold temperature anomaly within it throughout the entire troposphere. As the extratropical disturbance moved into the tropical WNP, deep convection associated with quasi-geostrophic dynamics over the warm ocean initiated tropical transition of the extratropical disturbance to a TC through diabatic redistribution of PV in the tropospheric column as well as transition of the cold anomaly into a warm anomaly within the vortex. With additional contribution of barotropic energy conversion in the lower troposphere, the warm-core low system finally developed into a TC-strength vortex. These results indicate that PV troughs of the stratospheric origin over the subtropical Pacific Ocean can contribute to TC formations in the WNP.

Research Area(s)

  • barotropic energy conversion, potential vorticity intrusion, subtropical cyclone, tropical cyclone, tropical transition, western North Pacific

Citation Format(s)

The Tropical Transition in the Western North Pacific: The Case of Tropical Cyclone Peipah (2007). / Chang, Minhee; Ho, Chang-Hoi; Chan, Johnny C. L. et al.
In: Journal of Geophysical Research: Atmospheres, Vol. 124, No. 10, 27.05.2019, p. 5151-5165.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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