臺灣東北海域湧升流之時空變化
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Date
2007-11-30
Authors
盧鴻復
吳朝榮
李忠潘
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Abstract
黑潮為世界重要洋流之一。前人觀測發現黑潮流經臺灣東北海域之時，受到東海陸棚走向之影響，黑潮與複雜的海底地形交互作用，在此處產生湧升流與冷渦現象。過去的研究多以現場觀測為主，難以連貫研究資料的時空變化。因此，本研究以普林斯頓大學所開發之三維海洋數值模式為基礎，採用真實地形與巢狀箝合方法，將較大範圍模式之輸出作為本模式之初始與邊界條件，建構一個水平空間解析度達1/20°之海流模式。本模式可用來模擬臺灣東北海域之海流運動，其結果成功地重建該處之流場與水文型態，藉由分析、研究模式資料，可以瞭解東北海域之流場時空變化。模擬結果顯示，黑潮衝擊陸棚產生湧升流，於表層以冷渦流場表現，此現象受到黑潮運動影響，有季節性的變化，與過去觀測結果一致。除此之外，模式資料更進一步明確表現東北海域冷渦流場在季節尺度內的變化，其資料分析結果反應觀測資料之缺憾，亦指出上層黑潮主軸之擺動週期受到不同機制的作用而有所差異，進而對東北海域之上層流場產生顯著影響。
Kuroshio is one of the most important currents worldwide. When Kuroshio impacts the zonal continental shelf break of East China Sea off northeast Taiwan, upwelling and cold eddies occur by the effect of interactivities between the Kuroshio and complicated topography. To study the spatial and temporal variations of circulation in the area, we construct a fine resolution model based upon POM with realistic bathymetry and nesting method. The current pattern northeast off Taiwan can be reproduced by this model. The simulation shows that upwelling is affected by the migration of the Kuroshio which is very consistent with the previous findings. Besides, model data further show an intra-seasonal variation of cold eddy off northeast Taiwan. The various period of Kuroshio migration is effected by the different mechanism in upper layer.
Kuroshio is one of the most important currents worldwide. When Kuroshio impacts the zonal continental shelf break of East China Sea off northeast Taiwan, upwelling and cold eddies occur by the effect of interactivities between the Kuroshio and complicated topography. To study the spatial and temporal variations of circulation in the area, we construct a fine resolution model based upon POM with realistic bathymetry and nesting method. The current pattern northeast off Taiwan can be reproduced by this model. The simulation shows that upwelling is affected by the migration of the Kuroshio which is very consistent with the previous findings. Besides, model data further show an intra-seasonal variation of cold eddy off northeast Taiwan. The various period of Kuroshio migration is effected by the different mechanism in upper layer.