臺灣聲學聯合海洋模式建立與臺灣東北海域水下偵測效能分析

Establishment of Taiwan Ocean-Acoustic Joint Model and Analysis of Detection Performance Northeast off Taiwan

倪禎陽(Chen-Yang Ni)

指導教授 ： 陳琪芳

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.00803

摘要

臺灣周邊海域水文環境複雜，且於實際狀況下以研究船收集水文資料有著諸多條件限制，如何能產生大範圍的水文溫鹽資料供音傳數值模式進行大範圍的音傳損耗預估計算一直是一項挑戰，而現今海洋物理的研究上已經普遍使用海洋模式來進行海洋水文環境隨著時間變動之研究，同時海洋模式也具備著現報及預報水文資料的能力，因此本研究藉由海洋模式提供大範圍時變性溫鹽資料的能力與音傳數值進行結合，進而能夠進行大規模的音傳損耗計算及聲納效能預估。
本論文首先以工業技術研究院之臺灣附近海域現報/預報系統為基礎建置四組(HYCOM/T24/T36/Q100)不同基礎邊界條件之海洋模式，並使用海洋學門資料庫之歷史資料進行水文方根誤差分析，比較四組海洋模式之水文準確度情形，結果顯示T24海洋模式水文準確度最佳。
由於增加潮汐對於水文的影響不可忽略，於T24模式疊加上TPXO潮汐模式，並選用2009年於臺灣東北海域執行之音傳實驗資料，以實驗CTD資料、T24及TCONFS模式三種水文資料模擬的音傳損耗進行誤差比對，分別得到均方根誤差為3.25、3.83及3.28dB，結果顯示TCONFS模式能夠達到與實際量測CTD相似的準確度。
接著使用TCONFS海洋模式針對臺灣東北海域進行大範圍偵測效能模擬分析，在環境噪音主導遮蔽的假設條件下，聲納偵測效能於陸棚地形主要受到海底地形起伏的影響而變化，而於陸坡地形下主要受到不同時間下的水文剖面狀況影響，於冬季偵測效能表現較佳，夏季偵測效能表現較差。

關鍵字

海洋模式 ； 臺灣東北海域 ； 音傳損耗 ； 偵測效能

並列摘要

The ocean environment around Taiwan is very complicated. It is highly limited in collecting hydrographic data with research ships. Thus ocean is always under-sampled in the study of water-column properties. Ocean circulation models are solution to this under-sample problem. We need the information of the entire water column of the area where we carry out numerical simulations of underwater acoustic propagation and sonar performance prediction. Ocean model have ability to do nowcast or forecast of hydrographic data. In this study, the goal is to establish a joint ocean and acoustic model by combining ocean model and sound propagation model to predict sonar performance in the area of interest by solving the sonar equation.
First of all, four ocean models (HYCOM/T24/T36/Q100) are established based on Taiwan Costal Ocean Nowcast/Forecast System (TCONFS) with different boundary condition. Then the root mean square error (RMSE) between historic hydrographic data of Ocean Data Bank and outputs from each ocean model are compared to estimate the accuracy each model. The results show the accuracy of T24 model is the best.
The tidal model TPXO is superposed on T24 model to better model the real ocean. The RMSE od transmission loss between the acoustic propagation experiment data and the results of sound propagation simulation using CTD data collected during the acoustic experiment, and ocean data of T24 and TCONFS model. The RMSE from these models and the acoustic data is 3.25, 3.83 and 3.28 dB respectively. In the following sonar performance calculation, the TCONFS model id used for it resembles the ocean environment most and the RMSE of the simulation data with the experimental data is compatible.
The sonar range analysis in the east-northern sea area of Taiwan is carried out with outputs of TCONFS model. Under the assumption of noise-limited condition, that predicted sonar range varies with bathymetry, and seasonal variation is clearly seen as the seasonal variation is present in the hydrographic condition.

並列關鍵字

Ocean Model ； North Men-Hua Canyon ； Transmission Loss ； Detection Performance

參考文獻

28. 苑梅俊, 淺海水域之水下音傳不確定性分析與偵測效能之研究. 臺灣大學工程科學及海洋工程學研究所學位論文, 2007: p. 1-166.

42. 湛翔智, 臺灣鄰近海域環境噪音之資料分析及數值模擬. 臺灣大學工程科學及海洋工程學研究所學位論文, 2007: p. 1-166.

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