Effect of ocean interannual variability on acoustic propagation in the Philippine Sea and South China Sea

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Authors
Yudono, Albert Mahendro
Subjects
interannual variability
Philippine Sea
South China Sea
thermohaline characteristics
sound speed
form of merit
acoustic transmission loss
Advisors
Chu, Peter C.
Margolina, Tetyana
Date of Issue
2017-06
Date
Jun-17
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
Effect of interannual variability of temperature and salinity on acoustic propagation in the Philippine Sea and South China Sea is investigated using the Navy's climatological (T, S) dataset [i.e., Generalized Digital Environmental Model (GDEM)] and the Synoptic Monthly Gridded World Ocean Database (SMG-WOD) data from January 1960 to December 2014, and an open source acoustic model (BELLHOP). The multi-year averaged monthly (T, S) profiles calculated from the SMG-WOD agree quite well with the GDEM with slight difference in upper layers, especially in thermoclines. The interannual variability of the transmission loss (TL) is identified using the BELLHOP model with the sound speed profiles calculated from the SMG-WOD and GDEM. Less TL was found in the convergence paths modelled from the SMG-WOD. Interannual (3-7 years) variabilities were found in each decade. The TL does not show strong interannual variabilities over the convergence paths; however, the interannual variability will affect the TL between the convergence paths, in the formation of surface duct, sound channels and bottom bounce. The SMG-WOD data is more suitable to assess the interannual variability effect on the acoustic propagation.
Type
Thesis
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Department
Oceanography
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Approved for public release; distribution is unlimited.
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