Study of Underwater Acoustic Transmission Loss Variation in Taiwan South-West and North-East Regions
Date Issued
2009
Date
2009
Author(s)
Huang, Cheng-Ken
Abstract
The purpose of this thesis is to study the variation of transmission loss in Taiwan’s South-West and North-East Regions during the occurrence of internal tide and eddies. Both the experimental data and simulation using temperature profile from ocean model are used for the study. In addition, the study used the result of ocean model as transmission loss simulation input, to compare the result of Range-independent and Range-dependent transmission loss simulation, and to understand the need of a complete ocean background during internal tide period. This thesis studied South-West and North-East Regions in Taiwan respectively. In the South-West Regions, the transmission loss experiment data analysis shows the variation of the transmission loss. We also used the results of three-dimensional tide model as inputs to compare the Range-independent and Range-dependent transmission loss simulation. The results showed that using single sound speed profile at source produced errors at simulation range large that 10 km. In North-East Region, this thesis studied how internal tide and eddies period affected transmission loss individually. The ocean backgrounds data of internal tide and eddies are from three-dimensional tide model and DUPOM (Duo Grid Pacific Ocean Model). The results of transmission loss simulation during internal tide period showed that the surface duct was an important factor affecting the transmission loss. The comparison of Range-independent and Range-dependent transmission loss simulation showed that the effect was higher in shallow water. The transmission loss simulation in eddies periods showed that the changes of transmission loss occurred where the iso-sound-speed-contours were inclined. Compare with the no-eddies period in winter, the occurrence of eddies raised the transmission loss up 1 to 6 dB. The effect was higher in deep water in spring and higher in shallow water in summer.
Subjects
Transmission Loss, Numerical Ocean Model,Underwater Acoustic,Variation
Type
thesis
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