博士 / 國立臺灣大學 / 工程科學及海洋工程學研究所 / 100 / Uncertainty of transmission loss (TL), resulted from the uncertainty of geophysical and physical oceanographic parameters (features), could consequently contribute to the uncertainty of sonar performance prediction. This research adopts coupled and combined modeling and data of field observations over the continental shelf and slope close to North Men-Hua Canyon offshore northeastern Taiwan in order to study the uncertainty of transmission loss. This area contains range-varying sediment type, rapid-changing bathymetry, and complex water column activities brought by the Kuroshio intrusion, which jointly induce a highly uncertain environment for sound propagation. Sound propagation in this area is observed and modeled to interpret the propagation effect of the water column and seabed. Finally, the uncertainty of ocean model output and transmission loss in this area is quantified. And the spatial and temporal effects on the ocean and acoustic field are also quantified in this thesis.
In this thesis, field survey data of Quantifying, Predicting, and Exploring Uncertainty (QPE) experiment is applied to study the uncertainties, include mid-frequency acoustic data, bathymetry data, sub-bottom survey data, and temperature data. The works finalized in this thesis includes (1) quantifying the uncertainty of TL and defining the optimal data set of bathymetry and geoacoustic, (2) combing ocean model and acoustic model, and giving the uncertainty of TL resulted by using this combined model, and (3) quantifying the uncertainty of ocean model output and analyzing it’s acoustic effects.
According to the results, the lower bound of the uncertainty of TL could be described by a Normal distribution with 0 dB mean and 3.8 dB standard deviation based on applying optimal bathymetry and geoacoustic data set and the CTD data. The uncertainties are similar on shelf region and shelf break region. On the other hand, while combining the Princeton Ocean Model and acoustic model to predict watercolumn and TL, the uncertainty of ocean model output varies with oceanographic features and could be categorized into three periods corresponding to the descending and the ascending of isothermal brought by internal tides and the emerging of cold water. The uncertainty of ocean model output would project on the uncertainty of TL and result in larger variation on the shelf region. The predicting results would likely to overestimate, close to, and underestimate the TL on the shelf region but have little influence on the predicting TL on the shelf break region.
The study of this thesis provides the quantification of the uncertainty of TL close to North Men-Hua Canyon offshore northeastern Taiwan. The results could be applied to verify and adjust the simulated TL and reduce the errors while applying TL prediction.
| Identifer | oai:union.ndltd.org:TW/100NTU05345014 |
| Date | January 2011 |
| Creators | Yuan-Ying Chang, 張元櫻 |
| Contributors | Chi-Fang Chen, 陳琪芳 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 122 |
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