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Tidal Current - Introduction

Tidal Current - Introduction. Chang Hsien Kuo. 國立交通大學土木工程學系 中華民國 102 年 3 月 21 日. Equipment: ADCP. ADCP: Acoustic Doppler Current Profilers Multi-layers (Three or ten Layers). Data Acquisition. Velocity : knot(0.51m/s) Azimuth: the current flows to that direction

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Tidal Current - Introduction

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  1. Tidal Current - Introduction Chang HsienKuo 國立交通大學土木工程學系 中華民國102年3月21日

  2. Equipment: ADCP • ADCP: Acoustic Doppler Current Profilers • Multi-layers (Three or ten Layers)

  3. Data Acquisition Velocity : knot(0.51m/s) Azimuth: the current flows to that direction wind or wave comes from that direction

  4. 第34屆海洋工程研討會 決定實測近岸水流 主方向的探討 張憲國、莊文傑、劉勁成 國立交通大學土木工程系所 中華民國101年11月23日

  5. 近岸水流主方向 Data analysis methods in physical oceangraphy: Emery and Thomson (1998) p.325-327 分散圖 (scatter plot):

  6. 近岸水流主方向

  7. 近岸水流主方向

  8. 近岸水流主方向 Wiegel (2005):風吹流(wind driven current)、波浪流(wave induced current)、潮流(tidal current)及洋流(ocean current) 等 分散圖 (scatter plot): 協變矩陣(covariance matrix)及求出特徵值方法(Freeland et al., 1975; Preisendorfer , 1988) 臺北港2009年整年實測水流之分散圖

  9. 近岸水流主方向 臺中港2009年整年實測水流之分散圖

  10. 水流主方向的判定方法 重心法(centroid of scatter plot)； 最小力矩法(minimum inertia moment about main axes) 最大方向分布(maximum probability density of directional distribution)。

  11. 重心法 群集分析(cluster analysis): Kmeans分群法 重心位置 圖1臺北港2009年整年實測水流之分散圖

  12. 重心法 前1/3大流速 大流速只出現在某小範圍之角度上，而小流速則較均勻出現在各方位上。因此大流速的流速資料更能清楚分群，且每群之重心可清楚表示流速之主方向。

  13. 最小慣性矩法 設兩分區水流的主方向如圖中之虛線，則逐時之水流速度對此主軸取慣性矩，即流速垂直於主軸距離為力臂 13

  14. 最大方向分布 將流速在各方向分布計算出其出現機率，在流速出現較多地方向定義為主方向 非參數化機率密度函數---Ksdensity 臺北港實測水流之方向機率分布圖 14

  15. 臺中港水流的主方向 圖6臺中港流速之分散圖 圖8方向機率分布圖 15

  16. 臺北港及臺中港的水流主方向 臺北港:本文三種方法獲得之結果發現水流主方向都相近，相差約2-3度，兩主方向差180度 臺中港:最小力矩法及方向分布法兩種決定水流主方向相近，但與重心法所得約有40至50度之差異。二個主方向之夾角並非180度。 16

  17. Harmonic Analysis for tidal current • Vector (two-dimensional variables) • E&N or (L&N) components • Harmonic Analysis for Ui and Vi

  18. Rotary component spectra • Emery and Thomson (1998) p.427-431)

  19. Rotary component spectra

  20. Rotary component spectra

  21. Rotary component spectra

  22. Rotary component spectra

  23. Rotary component spectra Major axis Minor axis Tilting angle Flatness

  24. Evaluation RMSE R2(determination of coefficient)

  25. Main components of tides and tidal current Taipei Harbor

  26. Main compinents of tides and tidal current KaoHsiung Harbor

  27. Astronomical tides Numerically simulated tides for Taipei and Anping harbor

  28. U-component of tidal current

  29. V-component of tidal current

  30. Main components of tides and tidal current

  31. Main components of tides

  32. Main components of tides and tidal current

  33. Main components of tides and tidal current

  34. Main components of tides and tidal current

  35. Main components of tides and tidal current

  36. Main components of tidal current

  37. Main components of tidal current

  38. Main components of tidal current

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