Western North Pacific Typhoons with Concentric Eyewalls
Abstract
This study examines the intensity change and moat dynamics of typhoons with concentric eyewalls using passive microwave data and best-track data in the western North Pacific between 1997 and 2006. Of the 225 typhoons examined, 55 typhoons and 62 cases with concentric eyewalls have been identified. The data indicate that approximately 57% of category 4 and 72% of category 5 typhoons possessed concentric eyewalls at some point during their lifetime. While major typhoons are most likely to form concentric eyewalls, the formation of the concentric structure may not be necessarily at the lifetime maximum intensity. Approximately onethird of concentric eyewall cases are formed at the time of maximum intensity. The moat is known to be heavily influenced by the subsidence forced by the two eyewalls. Rozoff et al. proposed that the rapid filamentation dynamics may also contribute to the organization of the moat. This paper examines the possibility of rapid filamentation dynamics by devising a filamentation moat width parameter. This parameter can be computed from the best-track typhoon intensity and the passive microwave satellite-estimated inner eyewall radius for each typhoon with concentric eyewalls. The filamentation moat width explains 40% of the variance of the satellite-observed moat width in the group with concentric eyewall formation intensity greater than 130 kt.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 19, 2009
- Accession Number
- ADA513367
Entities
People
- Chih-pei Chang
- Hau-jang Jiang
- Hybgchi Kuo
- Yi-ting Yang
Organizations
- Naval Postgraduate School