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題名 | 科氏效應與環境風場對海風環流之影響=Effects of Coriolis Force and Ambient Wind on Sea Breeze Circulations |
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作者 | 侯昭平; 許武榮; 吳清吉; 謝銘恩; 戴志輝; 林裕豐; | 書刊名 | 大氣科學 |
卷期 | 34:4 民95.12 |
頁次 | 頁335-351 |
分類號 | 328.52 |
關鍵詞 | 科氏效應; 海風鋒面; 對流邊界層; Coriolis effect; Sea-breeze front; Convective boundary layer; |
語文 | 中文(Chinese) |
中文摘要 | 本文使用臺大-普度二維非靜力模式(NTU-Purdue 2D nonhydrostatic model),以高解析度(Δx = Δz = 50 m)模擬科氏效應、環境風場對海風鋒面、環流和對流邊界層演化的影響。模擬結果顯示受科氏效應影響,海風通過時間越長,風向偏轉的角度越大,風速也越強;而其上的海風迴流風速較弱,偏轉效應較不明顯。科氏效應除了使海風偏向之外,也減弱海風向內陸延伸的距離和強度。在陸地上的對流邊界層裡,受紊流影響較大,其對流時間尺度短,因此對單一測站的科氏效應較不明顯。 由初始背景環境風場敏感測試顯示,初始風場為向岸風時,會增加海風向內陸穿透的距離,並將地表傳送至大氣的熱量,迅速的向下游傳送;初始風場為離岸風的結果則相反。但離岸風能夠縮短海風鋒面合併對流胞的時間,因此海風向內陸推進過程中,海風鋒面的強弱變化變得更為明顯。初始風場為靜風時,海風鋒面合併對流胞所需時間,明顯大於初始風場為離岸風的情況,海風鋒面雖也呈現明顯的強弱變化,但變化週期因此變長,模擬結果也顯示太強的環境風場(> 2 ms¯¹),會破壞海風環流和陸地對流邊界層的結構。 |
英文摘要 | The NTU/Purdue nonhydrostatic model is applied to study the effects of Coriolis force and the ambient wind speed on sea breeze circulations with a very high spatial resolution. We found that Coriolis force plays a very important role in the development of a sea breeze circulation. The direction of sea breeze is deflected with a weaker intensity and shorter distance of inland penetration by including the effect of earth's rotation in the model. However, the turbulence inside the convective boundary layer ahead of the sea breeze circulation remained unaffected. With an on-shore (same direction as the embedded sea breeze) wind speed, the sea breeze can penetrate farther inland and the surface heat flux behind the sea breeze front can be stronger with a strong wind speed near the ground surface. With an off-shore ambient wind speed, the process of merging of the sea breeze front and large eddies inside the inland convective boundary layer becomes very pronounced. The time scale of the merging process is much shorter with an off-shore ambient wind than the on-shore situation. However, when the ambient wind speed is too strong, the sea breeze circulation cannot develop at all. |
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