Author: |
施明甫 SHIH, MING-FU |
---|---|
Thesis Title: |
東太平洋間熱帶輻合帶的年際與年代際變化 The interannual and decadal variabilities of ITCZ over the eastern Pacific |
Advisor: |
陳正達
Chen, Cheng-Ta 洪致文 Hung, Chih-Wen |
Degree: |
碩士 Master |
Department: |
地球科學系 Department of Earth Sciences |
Thesis Publication Year: | 2011 |
Academic Year: | 99 |
Language: | 中文 |
Number of pages: | 105 |
Keywords (in Chinese): | 東南太平洋間熱帶輻合帶 、間熱帶輻合帶 、年代際變化 、年際變化 |
Keywords (in English): | Southeast Pacific intertropical convergence zone, Intertropical convergence zone, El Nino/Southern Oscillation |
Thesis Type: | Academic thesis/ dissertation |
Reference times: | Clicks: 241 Downloads: 16 |
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熱帶海洋地區有許多對流發展,稱為間熱帶輻合帶(Intertropical convergence zone;簡稱ITCZ)。其中的東南太平洋間熱帶輻合帶(Southeast Pacific intertropical convergence zone;簡稱SITCZ)位於東太平洋赤道南方,每年2~4月才會發展對流系統。分析顯示,東太平洋赤道北方的間熱帶輻合帶(簡稱NITCZ)和SITCZ的3~4月強度有年代際變化,由於赤道南方的海表面溫度(Sea surface temperature;簡稱SST)在1982年以後大幅上升,有利對流發展,且也使負值SST南北向梯度加強,導致原本的東南風減弱較多,而使SITCZ的輻合增強。NITCZ則因為對應SST原
本已高,SST略增對於對流強度增強沒有明顯幫助。年際變化方面,本研究先分析El Nino/Southern Oscillation(簡稱ENSO)對ITCZ的影響,發現強聖嬰年時,高SST是影響對流發展的主因。而SITCZ在強反聖嬰年,因為強的SST梯度會使輻合動力機制提前於2月發生,使SITCZ於3~4月能夠顯著發展。另外在研究的分析中也顯示SITCZ區域的SST並非影響SITCZ強度的唯一機制。利用高解析度資料分析,當NITCZ區域的SST在北半球冬季及春季較高時,3~4月的NITCZ可以維持較強強度,進而利用動力機制壓抑赤道南邊的SITCZ環流,使SITCZ較弱;反之若NITCZ區域的SST在南半球夏季及秋季較低溫時,3~4月的NITCZ則會明顯減弱,動力機制壓抑赤道南邊SITCZ的情形相對不明顯,因此SITCZ會較強。
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