碩士 / 臺北市立大學 / 地球環境暨生物資源學系環境教育與資源碩士班 / 105 / This research demonstrated interdecadal change of tropical cyclones (TC) genesis position and the physical mechanism produce the interdecadal change of the TC genesis position. The observations shows that TC genesis position are changing with a significant interdecadal variability in the late 1990s, before the late 1990s, TC mean genesis position tend to move toward equator and easterly, after the late 1990s, it’s tend to move poleward and westerly in versa.
In this study, the period of TC genesis position move toward equator before the late 1990s. Monsoon trough of West-North Pacific (WNP) and pressure trough of South Pacific (SP) are being enhanced, in the same time, South Pacific Convergence Zone (SPCZ) tend to move easterly, this eastern move is associated with Sea Surface Temperature (SST) changed with Interdecadal Pacific Oscillation (IPO). During the IPO positive phase, warm SST anomaly in the equator East Pacific produce lows circulation anomaly in both WNP and WSP through Matsuno-Gill type response. Conversely, after the 1990s, cold SST anomaly accompanied by IPO negative phase produce high pressure circulation anomaly in west Pacific, which intense WNPSH and South Pacific High then promote SPCZ move westerly, result in TC mean genesis position move poleward and westerly. Owing to South Pacific High not move as western as WNPSH, WSP TC mean genesis latitude is less than WNP.
Not only IPO but also warm SST driven by North Atlantic (NA) affect Mean Genesis Position (MGP) after 1990s. Warm SST in NA produce longitude side Walker circulation, result in ascend motion in Atlantic and descend motion in Central Pacific (CP). Descend motion in CP enhance westerly wind anomaly in West Pacific, also enhance WNPSH and SPH. This phenomenon cause highs system move westerly and intense the vertical wind shear and then mesoscale environment factor isn’t fit TC genesis. Partial correlation analysis reveals that WNPSH move westerly is more likely causing by warm SST in NA than IPO. Conversely, in SP, SPH move westerly primary causing by IPO.
| Identifer | oai:union.ndltd.org:TW/105UT005007014 |
| Date | January 2017 |
| Creators | Chen, Ming-Syuan, 陳明宣 |
| Contributors | Hong, Chi-Cherng, 洪志誠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 66 |
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