黑潮主流受地形影響，於臺灣東北海域湧升並產生冷渦(Cold Eddy)的現象，已被研究了數十年，惟仍多利用現場觀測或遙測判定海表面高度異常等方式研究及追蹤冷渦，受到垂直分層與時間連續觀測資訊的限制，無法深入瞭解其在不同深度的消長機制。本研究利用由國家海洋資料庫及共享平台(National Ocean Database And Sharing System, NODASS)所提供具大範圍、長時間不間斷且通過資料同化提高可信度的混合座標海洋模式(HYbrid Coordinate Ocean Model, HYCOM)之追算資料，再結合Nencioli等人所開發的基於向量幾何的渦旋演算法建構一套單純利用速度場判斷臺灣東北海域冷渦的流程，藉此了解冷渦在不同深度消長的情形以及與黑潮的關係，得到以下結果：1. 冷渦在深層會與表層一樣受到黑潮擺盪而有消長的現象。2. 由深度0至500公尺受到地形的影響，冷渦中心分佈呈西北至東南走向。3. 冷渦普遍在深度100公尺有面積相對極大值。根據以上結果，本研究推測冷渦在深層與表層受到黑潮擺盪而有同樣的消長表現是因為冷渦源自於受地形影響而湧升的黑潮，意即黑潮是由深層湧升至表層，因此深層消長情形與表層一致是合理的。綜上所述，臺灣東北海域冷渦分布及消長情形會受到黑潮及地形相互作用影響，此外，深層的消長亦會與表層一致，這與前人研究乃相異之處。

The phenomenon of Kuroshio mainstream upwelling and generating cold eddies off the northeastern Taiwan has been studied for decades. However, most research and tracking of cold eddies have deeply relied on in-situ observations or remote sensing to determine anomalies in sea surface height. These methods are limited by vertical stratification and continuous observation data over time, which restricts a deeper understanding of the growth and decay mechanisms of cold eddies at different depths. This study utilizes the hindcast data provided by the National Ocean Database and Sharing System (NODASS), which offers extensive, long-term, continuous data with enhanced credibility through data assimilation, using the HYbrid Coordinate Ocean Model (HYCOM). Combining this with the vector geometry-based eddy detection algorithm developed by Nencioli et al., we establish a process that solely uses velocity fields to identify cold eddies off the northeastern Taiwan. Through this approach, we gain insights into the growth and decay of cold eddies at various depths and their relationship with the Kuroshio. The following conclusions were drawn: 1. Cold eddies at deeper layers exhibit growth and decay phenomena similar to those at the surface, influenced by Kuroshio oscillations. 2. The distribution of cold eddy centers from depths of 0 to 500 meters shows a northwest to southeast orientation. 3. Cold eddies generally have a relatively maximum area at a depth of 100 meters.

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