氣候變遷下黑潮於臺灣東北的入侵變動

Variability of the Kuroshio Intrusion off northeast Taiwan under Climate Change

蔡昀展(Yun-Chan Tsai)

指導教授 ： 張懿

國立成功大學/工學院/海洋科技與事務研究所/碩士(2019年)

摘要

西太平洋邊緣海的重要海流黑潮有時會侵入呂宋海峽和臺灣東北大陸棚，然後進入南海(SCS)和東海(ECS)，這也影響沿海水動力環境和傳輸熱量，因此，了解黑潮在氣候變遷下的變動模式是必要的。
本研究利用衛星流場、風應力和海洋表面溫度資料來探討黑潮的兩個入侵熱點之間季節變動的關係，並且建立路徑分析模型說明變數間的因果關係，結果顯示臺灣東北的入侵強度與流場、風應力甚至與PDO及ONI指標有關，同時也說明兩個入侵熱點的季節變動一致性，在冬季時容易蜿蜒入侵呂宋海峽及臺灣東北，導致黑潮入侵增強，然而夏季時，黑潮路徑相對筆直，使黑潮入侵減弱。
將海表溫鋒面定義為黑潮入侵指標，再利用經驗模態分解法解釋氣候變遷下黑潮入侵呂宋海峽和臺灣東北部的長期趨勢(1985-2017)。結果顯示長期以來呂宋海峽的黑潮入侵持續減少，而臺灣東北部的入侵1990年代後逐漸增強。根據海流數據顯示，菲律賓東側的黑潮逐年增強，因此黑潮主流快速向北流動，導致入侵呂宋海峽的海流減少；然而，黑潮持續向北流至臺灣東部後主流流速卻減弱，也因此強化了臺灣東北部陸棚的入侵現象。

關鍵字

黑潮 ； 海表溫鋒面 ； 氣候變遷 ； 經驗模態分解

並列摘要

The water and material exchange between oceans and ocean currents are crucial because it can modulate the water mass and ecosystem in marginal sea. Therefore, understanding the pattern of the Kuroshio variation under climate change is necessary for understanding its possible effects on biophysical processes in the marginal seas of the West Pacific Ocean.
This study employed satellite geostrophic current, wind stress, and sea surface temperature (SST) oceanic front data to examine the seasonal variation in the two hotspots of Kuroshio intrusion. A path analysis model was established to explain the causation between paired parameters. The results show Kuroshio intrusion in northeastern Taiwan relates to current, wind stress, Pacific Decadal Oscillation (PDO), and Oceanic Niño Index (ONI). The Kuroshio current meanders toward the Luzon Strait and northeastern Taiwan during winter, when PDO and wind stress exhibited a positive relationship with Kuroshio intrusion, whereas ONI had a negative effect on the intrusion.
The SST fronts, which has been used as a Kuroshio intrusion index during 1985–2017, was examined through an empirical mode decomposition (EMD) approach to examine the long-term Kuroshio variation under climate change. The results revealed that the Kuroshio intrusion in the Luzon Strait has been continuously decreased from 1990s and increased in northeastern Taiwan in the last decade. According to current speed, when the northward Kuroshio current in the east Philippines was faster, the westward intrusion into the Luzon Strait decreased. Moreover, the Kuroshio current flowed farther toward the east Taiwan, and the low current velocity enhanced the Kuroshio intrusion in northeastern Taiwan.

並列關鍵字

Kuroshio ； sea surface temperature front ； climate change ； empirical mode decomposition

參考文獻

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