- 學位論文
淺海環境水文及底質對音傳特性之影響
Environmental Effects on Sound Propagation in Shallow Waters
摘要
本文目的為比較ASIAEX南海實驗音傳損耗(Transmission Loss)的資料與數值模擬結果，並探討水文及底質特性對淺海聲音傳播的影響。文中主要探討在ASIAEX南海實驗中，J-15-3第二條拖曳路徑中(5月5日23：31到5月6日00：23之間) CW訊號在140Hz時的音傳損耗，並將其理論計算與實際資料相比，發現數值模擬可因水文(內波)及底質參數之輸入調整，而與資料結果相仿，因此探討水文及底質特性問題。底質算例結果顯示底層聲速越高其音傳損耗越小，由聲源頻率50∼300Hz的結果發現，聲源頻率越低底層有效深度越深，而聲源頻率增加其有效深度則減少。水文算例結果顯示由內波所產生的音傳擾動會更加紊亂，因而在實際水文環境中，找出內波切確位置及速度就極為重要。
並列摘要
The comparison between the data of the transmission loss in the ASIAEX SCS experiment and the result of the numerical simulations is presented in this paper. In addition, we try to discuss the effect of water column and sediment property on the acoustic propagation in the ocean. In this paper, we mainly discuss the transmission loss of CW tones transmitted in 140 Hz during a segment of J-15-3 RUN2 which started at 05/05 23:31 and ended in 05/06 00:23. Furthermore, according to the comparison between theoretical calculations and practical data, we found the result of the numerical simulations would be similar to the practical data if the parameter of water column (internal wave) and sediments are corrected. Therefore, it is necessary to consider water column as well as sediment property further. The result of the calculation of the sediment shows the transmission loss would get lower as the sound speed gets higher and in 50-300Hz range, the effect depth of the sediment is an inverse proportion to the source frequency. The results of water column case show that due to internal waves, the fluctuation in sound propagation becomes severer. Therefore it is very important to find out the exact locations and speed of internal waves in the real ocean environment.