Interdecadal Variability of the Strong Typhoon in Autumn

• Main Authors: Chia-Jung Lee, 李佳容
• Other Authors: Chih-Hua Tsou
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/62090673380846830688

碩士 === 國立臺灣師範大學 === 地球科學系 === 96 === Tropical storm (TS) activity has strong impacts on the weather and climate over western North Pacific (WNP) Ocean. This study found that the activity of strong (categories 4-5) typhoon exhibits significant interdecadal variability, while the signal of interdecadal variability of categories 1-3 typhoon is not obvious. Since TS events in summer have received considerable attention, recently, this study focuses on the interdecadal variability of super typhoon activity in autumn. The ratio of the number of strong typhoon to the total number of typhoon (RST) in autumn is 29.3％. The RST during the strong typhoon active and inactive period are 33.8％ and 19.6％ respectively. The strong typhoon activity over the WNP Ocean in autumn is strongly influenced by the large-scale environment change over the central-eastern Pacific Ocean. During active period the warm sea surface temperature (SST) and high moisture content occur over the central-eastern Pacific Ocean. These conditions lead the formation of strong typhoon to extend south-eastward to the Date Line. On the contrary, the formation area of strong typhoon is restricted to the west of 160°E during inactive period. Thus, the strong typhoons have longer (shorter) journey and life span on the warm ocean during active (inactive) period. The interdecadal variability of the thermodynamic condition over the central Pacific is curial to the interdecadal change of strong typhoon in autumn over WNP Ocean. This study will further investigate the IPCC AR4 air-sea coupled model simulation to estimate the trend of strong typhoon after global warming.