Coupled Ocean-Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification and Dynamical Sensitivities
In this paper, we quantify the dynamical causes and uncertainties of striking differences in acoustic transmission data collected on the shelf and shelfbreak in the northeastern Taiwan region within the context of the 2008 Quantifying, Predicting, and Exploiting Uncertainty (QPE 2008) pilot expe...
| Main Authors: | , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
Institute of Electrical and Electronic Engineers / IEEE Oceanic Engineering Society
2011
|
| Online Access: | http://hdl.handle.net/1721.1/65649 https://orcid.org/0000-0002-1869-3883 |
| _version_ | 1826191874961965056 |
|---|---|
| author | Lermusiaux, Pierre F. J. Xu, Jinshan Chen, Chi-Fang Jan, Sen Chiu, Linus Y. Yang, Yiing-Jang |
| author2 | Massachusetts Institute of Technology. Department of Mechanical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Mechanical Engineering Lermusiaux, Pierre F. J. Xu, Jinshan Chen, Chi-Fang Jan, Sen Chiu, Linus Y. Yang, Yiing-Jang |
| author_sort | Lermusiaux, Pierre F. J. |
| collection | MIT |
| description | In this paper, we quantify the dynamical causes and
uncertainties of striking differences in acoustic transmission data
collected on the shelf and shelfbreak in the northeastern Taiwan
region within the context of the 2008 Quantifying, Predicting, and
Exploiting Uncertainty (QPE 2008) pilot experiment. To do so, we
employ our coupled oceanographic (4-D) and acoustic (Nx2-D)
modeling systems with ocean data assimilation and a best-fit
depth-dependent geoacoustic model. Predictions are compared
to the measured acoustic data, showing skill. Using an ensemble
approach, we study the sensitivity of our results to uncertainties
in several factors, including geoacoustic parameters, bottom
layer thickness, bathymetry, and ocean conditions. We find that
the lack of signal received on the shelfbreak is due to a 20-dB
increase in transmission loss (TL) caused by bottom trapping of
sound energy during up-slope transmissions over the complex
and deeper bathymetry. Sensitivity studies on sediment properties
show larger but isotropic TL variations on the shelf and smaller
but more anisotropic TL variations over the shelfbreak. Sediment
sound-speed uncertainties affect the shape of the probability
density functions of the TLs more than uncertainties in sediment
densities and attenuations. Diverse thicknesses of sediments lead
to only limited effects on the TL. The small bathymetric data
uncertainty is modeled and also leads to small TL variations. We
discover that the initial transport conditions in the Taiwan Strait
can affect acoustic transmissions downstream more than 100 km
away, especially above the shelfbreak. Simulations also reveal
internal tides and we quantify their spatial and temporal effects
on the ocean and acoustic fields. One type of predicted waves are
semidiurnal shelfbreak internal tides propagating up-slope with
wavelengths around 40–80 km, horizontal phase speeds of 0.5–1
m/s, and vertical peak-to-peak displacements of isotherms of 20–60
m. These waves lead to variations of broadband TL estimates over
5–6-km range that are more isotropic and on bearing average
larger (up to 5–8-dB amplitudes) on the shelf than on the complex
shelfbreak where the TL varies rapidly with bearing angles. |
| first_indexed | 2024-09-23T09:02:38Z |
| format | Article |
| id | mit-1721.1/65649 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T09:02:38Z |
| publishDate | 2011 |
| publisher | Institute of Electrical and Electronic Engineers / IEEE Oceanic Engineering Society |
| record_format | dspace |
| spelling | mit-1721.1/656492022-09-26T10:03:05Z Coupled Ocean-Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification and Dynamical Sensitivities Lermusiaux, Pierre F. J. Xu, Jinshan Chen, Chi-Fang Jan, Sen Chiu, Linus Y. Yang, Yiing-Jang Massachusetts Institute of Technology. Department of Mechanical Engineering Lermusiaux, Pierre F. J. Lermusiaux, Pierre F. J. Xu, Jinshan In this paper, we quantify the dynamical causes and uncertainties of striking differences in acoustic transmission data collected on the shelf and shelfbreak in the northeastern Taiwan region within the context of the 2008 Quantifying, Predicting, and Exploiting Uncertainty (QPE 2008) pilot experiment. To do so, we employ our coupled oceanographic (4-D) and acoustic (Nx2-D) modeling systems with ocean data assimilation and a best-fit depth-dependent geoacoustic model. Predictions are compared to the measured acoustic data, showing skill. Using an ensemble approach, we study the sensitivity of our results to uncertainties in several factors, including geoacoustic parameters, bottom layer thickness, bathymetry, and ocean conditions. We find that the lack of signal received on the shelfbreak is due to a 20-dB increase in transmission loss (TL) caused by bottom trapping of sound energy during up-slope transmissions over the complex and deeper bathymetry. Sensitivity studies on sediment properties show larger but isotropic TL variations on the shelf and smaller but more anisotropic TL variations over the shelfbreak. Sediment sound-speed uncertainties affect the shape of the probability density functions of the TLs more than uncertainties in sediment densities and attenuations. Diverse thicknesses of sediments lead to only limited effects on the TL. The small bathymetric data uncertainty is modeled and also leads to small TL variations. We discover that the initial transport conditions in the Taiwan Strait can affect acoustic transmissions downstream more than 100 km away, especially above the shelfbreak. Simulations also reveal internal tides and we quantify their spatial and temporal effects on the ocean and acoustic fields. One type of predicted waves are semidiurnal shelfbreak internal tides propagating up-slope with wavelengths around 40–80 km, horizontal phase speeds of 0.5–1 m/s, and vertical peak-to-peak displacements of isotherms of 20–60 m. These waves lead to variations of broadband TL estimates over 5–6-km range that are more isotropic and on bearing average larger (up to 5–8-dB amplitudes) on the shelf than on the complex shelfbreak where the TL varies rapidly with bearing angles. 2011-09-12T19:44:08Z 2011-09-12T19:44:08Z 2010-10 2010-08 Article http://purl.org/eprint/type/JournalArticle 0364-9059 INSPEC Accession Number: 11673991 http://hdl.handle.net/1721.1/65649 Lermusiaux, P.F.J. et al. “Coupled Ocean–Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification, and Dynamical Sensitivities.” Oceanic Engineering, IEEE Journal Of 35.4 (2010) : 895-916. © 2010 IEEE https://orcid.org/0000-0002-1869-3883 en_US http://dx.doi.org/10.1109/JOE.2010.2068611 IEEE journal of oceanic engineering Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Institute of Electrical and Electronic Engineers / IEEE Oceanic Engineering Society MIT web domain |
| spellingShingle | Lermusiaux, Pierre F. J. Xu, Jinshan Chen, Chi-Fang Jan, Sen Chiu, Linus Y. Yang, Yiing-Jang Coupled Ocean-Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification and Dynamical Sensitivities |
| title | Coupled Ocean-Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification and Dynamical Sensitivities |
| title_full | Coupled Ocean-Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification and Dynamical Sensitivities |
| title_fullStr | Coupled Ocean-Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification and Dynamical Sensitivities |
| title_full_unstemmed | Coupled Ocean-Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification and Dynamical Sensitivities |
| title_short | Coupled Ocean-Acoustic Prediction of Transmission Loss in a Continental Shelfbreak Region: Predictive Skill, Uncertainty Quantification and Dynamical Sensitivities |
| title_sort | coupled ocean acoustic prediction of transmission loss in a continental shelfbreak region predictive skill uncertainty quantification and dynamical sensitivities |
| url | http://hdl.handle.net/1721.1/65649 https://orcid.org/0000-0002-1869-3883 |
| work_keys_str_mv | AT lermusiauxpierrefj coupledoceanacousticpredictionoftransmissionlossinacontinentalshelfbreakregionpredictiveskilluncertaintyquantificationanddynamicalsensitivities AT xujinshan coupledoceanacousticpredictionoftransmissionlossinacontinentalshelfbreakregionpredictiveskilluncertaintyquantificationanddynamicalsensitivities AT chenchifang coupledoceanacousticpredictionoftransmissionlossinacontinentalshelfbreakregionpredictiveskilluncertaintyquantificationanddynamicalsensitivities AT jansen coupledoceanacousticpredictionoftransmissionlossinacontinentalshelfbreakregionpredictiveskilluncertaintyquantificationanddynamicalsensitivities AT chiulinusy coupledoceanacousticpredictionoftransmissionlossinacontinentalshelfbreakregionpredictiveskilluncertaintyquantificationanddynamicalsensitivities AT yangyiingjang coupledoceanacousticpredictionoftransmissionlossinacontinentalshelfbreakregionpredictiveskilluncertaintyquantificationanddynamicalsensitivities |