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題 名 | An Influence of Bottom Topography on the Western Boundary Current=海底地形對西邊界流的影響 |
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作 者 | 楊海軍; 劉秦玉; 李薇; | 書刊名 | 臺灣海洋學刊 |
卷 期 | 37:1 1998.06[民87.06] |
頁 次 | 頁77-88 |
分類號 | 351.926 |
關鍵詞 | 底形; 底形誘生的邊界流; 坡折; Bottom topography; BT induced boundary current; Slope break; |
語 文 | 英文(English) |
中文摘要 | 本文利用一考慮底摩擦的線性准地轉模式研究了封閉海盆內不同底形對西邊界流 的影響。共設計了四種底形,十二組試驗,利用數值方法來求解准地轉渦度方程。由于底形 坡度的存在,渦管在西邊界被壓縮,從而可在西邊界產生一強的北向流,本文稱之為底形誘 生的邊界流(BBC),其主軸的位置定義為三分之二最大流速的位置會隨底形的不同而發生變 化。底形除了有相當β效應外,其坡度還與BBC的強度及主軸的位置密切相關。對線性底形 坡度且底形寬度不小于邊界流的寬度的情況下,底形越陡,則BBC越強,並且BBC的主軸越接 近西邊界。若底形的坡度從西至東由平變陡且存在坡折,則坡折的位置將顯著影響BBC的速 度和寬度。若坡折離西邊界較遠,則緊靠西邊界的北向流速會減弱並且BBC的寬度會增加, 即使BBC主軸的位置向東移動,靠近坡折。考慮β效應的數值試驗結果與不考慮β效應的結 果定性相似,只是β效應和底形的聯合作用會使西邊界流略為變窄和變弱。 |
英文摘要 | In this paper a linear quasi-geostrophic model with Rayleigh friction for an enclosed oceanic basin is developed to investigate the effects of different types of bottom topography (BT). The numerical method is used to solve the vorticity equation, and twelve experiments are designed to show the patterns of the Western Boundary Current (WBC) when influenced by four types of BT. The compression of vortex tubes by the slope of the BT and the bottom frictional force can generate a strong northward current in the western boundary. The location of the main axis (defined as the position of the two-third maximum northward current) of the BT-induced boundary current (BBC) varies with different BT. Besides acting in the same way as the β-effect, the BT slope is tightly related to the strength of the BBC and its main axis location. For a linear slope, there is a positive correlation between the steepness of slope and the strength of the BBC in the case where the slope width is no less than that of the boundary current. A steeper slope can force a stronger BBC and cause its main axis to shift closer to the western boundary. If the slope varies from flat to steep for a certain BT and if there is a slope break, the location of the slope break can have a remarkable effect on the velocity and width of the BBC. If the slope break is far away from the western boundary, it may well weaken the velocity near the boundary and increase the width of the BBC. As a result, the main axis of the BBC is moved in an eastward fashion gaining closer proximity to the slope break. The results of numerical experiments with the β-effect are qualitatively the same as those without. The combined effect of β and BT makes the WBC slightly narrower and weaker. |
本系統中英文摘要資訊取自各篇刊載內容。