92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 5:00 PM
Long-Term Changes in Typhoon Intensity Over the Sub-Region of the Western North Pacific
Room 355 (New Orleans Convention Center )
Doo-Sun R. Park, Seoul National University, Seoul, South Korea; and C. H. Ho

Typhoon is the representative natural disaster, which resulting in enormous economic losses and thousands of casualties in coastal cities over the western North Pacific (WNP) every year. Typhoon forms and develops over the warm pool of oceans because the warm humid condition in the low troposphere is one of the most important factors for typhoon developing. In addition, the relationship between typhoon intensity and sea surface temperature is known as linearly positive relation. In this regard, as global warming being issued, a lot of researchers and politicians have concerned about the long-term variability of typhoon intensity. Based on the observations, some studies showed that typhoons become stronger in the recent decade [Emanuel 2005, Webster et al., 2005], but others suggested that it is hard to find the significant signals [Landsea, 2005; Chan, 2006]. These directly-opposed results are because of the inhomogeneity among the various typhoon datasets [Wu et al., 2006]. Most of previous studies focused on the basin-wide change in the typhoon intensity. In this study, the typhoon intensity is examined in the perspective of regional change because the atmospheric and oceanic conditions could be distinct in the each sub-region of the WNP. To minimize the inconsistencies among the typhoon datasets, four typhoon datasets (issued by Regional Specialized Meteorological Center Tokyo, Joint Typhoon Warning Center, Hong Kong Observatory, and China Meteorological Administration Shanghai Typhoon Institute) are used. The analysis period is 19772009, which is the years geostationary satellites operating. And the typhoons which form in June to October are only considered. Briefly, our result shows that typhoons become weaker (stronger) significantly in the low-latitude region (the mid-latitude region). It is thought that these opposite trends are mainly due to different large-scale environment such as sea surface temperature, vertical wind shear, and vertical wind.

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