2011-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/712576摘要：本計畫之研究目的可分為兩方面：其一為利用海面環境噪音為聲源以遙測海床與底 層海床之聲學性質， 其二為研究環境噪聲強度與颱風風力的相關性。藉由適當的訊號 處理技術，水聲學者Siderius, Harrison, and Porter等由接收到的海洋環境噪音為聲源被 動式估計海床之性質，相較於傳統方法以主動方式發出聲波以探測海洋環境。本研究 擬探討以被動式遙測海洋環境之環境影響因子：最小風速&#65380;處理器之準確度與解析度 與噪音時間長度的關係&#65380;最佳化的水聽器間距與陣列長度。 颱風的強度是以近中心附 近平均最大風速為準，因此精確的風速量測影響颱風強度預報。目前衛星影像遙測的 技術在估算颱風強度上尚有40%的誤差，近年來Wilson and Makris (J. Acoust. Soc. Am. 2006) 提出利用水聲為工具，藉由環境噪音強度與風速間的相關性，以估算颱風強度。 此方法之成本遠較使用大型偵察飛機或噴射機穿越颱風中心量測大氣資料來的低。本 研究計畫將探討的主題有：噪音聲源強度與風速之冪指數率關係於颱風下高風速之適 用性，碎波特性對海洋環境噪音之影響，在高風速下氣泡對於聲能衰減之影響。 <br> Abstract: The objective of this project is twofold: first, to determine the conditions with which the bottom and sub-bottom properties can be estimated using breaking waves as acoustic sources in the environments of interest, and, second, to study the dependence of the acoustic intensity generated by wind force accompanied with typhoon. Recent effort [SHP06] has developed a method, based on the Fourier synthesis technique, to exploit the ocean`s ambient noise field due to breaking waves to determine bottom properties passively. Issues to be addressed include: the minimum wind speed, the accuracy and resolution of the fathometer process as a function of averaging time, and the optimal phone spacing and array depth. Accurate wind speed measurements within hurricanes/typhoons are necessary in predicting their destructive power. Current satellite-based measurements yield estimates with error up to 40%. Recent analysis (Wilson and Makris, J. Acoust. Soc. Am. 2006) has proposed that acoustic means of measuring hurricane/typhoon winds may be practical for a much lower cost than currently used reconnaissance flights. Issues to be addressed in this effort involve: determining the validity of power-law relationship between acoustic source strength and wind speed in typhoon force winds, investigating the effect of the different characteristics of wave breaking, and determining the effect of acoustic attenuation due to bubbles at high wind speeds.被動音測學環境噪音颱風風速Passive acoustic tomographyAmbient noiseTyphoonsWind speed