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Estimation of Measurement Uncertainty of Seafloor Acoustic Backscatter.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Estimation of Measurement Uncertainty of Seafloor Acoustic Backscatter./
作者:	Malik, Mashkoor .
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
面頁冊數:	189 p.
附註:	Source: Dissertations Abstracts International, Volume: 81-08, Section: B.
Contained By:	Dissertations Abstracts International81-08B.
標題:	Acoustics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=27546403
ISBN:	9781392431078

Estimation of Measurement Uncertainty of Seafloor Acoustic Backscatter.
Malik, Mashkoor .

Estimation of Measurement Uncertainty of Seafloor Acoustic Backscatter. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 189 p.

Source: Dissertations Abstracts International, Volume: 81-08, Section: B.

Thesis (Ph.D.)--University of New Hampshire, 2019.

This item must not be sold to any third party vendors.

In the last three decades, Multibeam echo sounders (MBES) have become the tool of choice to study the seafloor. MBES collects two distinct types of data: bathymetry that provides topographic details of the seafloor and backscatter that has the potential to characterize the seafloor. While the uncertainty associated with MBE bathymetry has been well studied, the uncertainty in MBES backscatter measurement has received relatively little attention, hindering the improvements in quantitative analysis of backscatter data. Both acquisition and processing stages can introduce uncertainty in the final seafloor backscatter products. Application of well-established uncertainty quantification principles to seafloor backscatter data is challenging for several reasons: the uncertainty sources are not well known, they vary on a case-by-case basis, and standards do not exist for acquisition and processing. This dissertation focuses on assessing uncertainty in backscatter measurements and is comprised of four separate but related studies that identify and address the challenges of uncertainty quantification of backscatter measurements. The first study (Lucieer et al., 2018) which is presented as background, describes an end users' survey identifying key uses and challenges of backscatter data acquisition and processing. The study identified that consistency and repeatability of backscatter measurements is a major constraint in the use and re-use of backscatter. The second study (Malik et al., 2018), identified the sources of uncertainty and categorized them as significant or insignificant based on various use cases. The most significant sources of uncertainty were found to be inherent statistical fluctuations in the backscatter measurement, calibration uncertainty, seafloor slope and water column absorption estimation. While calibration uncertainty remains the main issue in advancing the quantitative use of the backscatter, the other sources were also shown to cause large uncertainties. These include non-standardized methods used to account for seafloor slope and absorption, and data interpretation errors due to missing background information about the processing procedures. With a comprehensive list of uncertainty sources established, two uncertainty sources, seafloor slope and processing errors, were examined further in the third (Malik, 2019) and the fourth (Malik et al., submitted) study respectively. Seafloor slope corrections are important to correct for both the area insonified and the incidence angle. Both of these corrections are adversely affected if seafloor slope corrections are not applied. Even in cases where the seafloor slope is used, further uncertainty can occur if the highest resolution bathymetry is not used. The results from this study showed that for the purpose of accurate slope corrections, the spatial scale of backscatter data should be selected based on the best available bathymetry. The majority of end users depend on third-party software solutions to process the backscatter data. The fourth study evaluated the output of three commonly used software packages after inputting the same data set and found that there were significant differences in the outputs. This issue was addressed by working closely with software developers to explore options to make the processing chain more transparent. Two intermediate processing stages were proposed and implemented in three commonly used software tools. However, due to proprietary restrictions, it was not possible to know the full details of the software processing packages. Differing outputs likely result, in part, from the different approaches used by the various software packages to read the raw data. Quality assessment and uncertainty quantification of MBES backscatter measurements is still at an early stage and further work is required to develop data acquisition and processing standards to improve consistency in the backscatter acquisition and processing.

ISBN: 9781392431078Subjects--Topical Terms:

879105
Acoustics.
Subjects--Index Terms:

Multibeam echo sounder

Estimation of Measurement Uncertainty of Seafloor Acoustic Backscatter.
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100 1 $a Malik, Mashkoor . $3 3546193
245 1 0 $a Estimation of Measurement Uncertainty of Seafloor Acoustic Backscatter.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2019
300 $a 189 p.
500 $a Source: Dissertations Abstracts International, Volume: 81-08, Section: B.
500 $a Advisor: Mayer, Larry.
502 $a Thesis (Ph.D.)--University of New Hampshire, 2019.
506 $a This item must not be sold to any third party vendors.
520 $a In the last three decades, Multibeam echo sounders (MBES) have become the tool of choice to study the seafloor. MBES collects two distinct types of data: bathymetry that provides topographic details of the seafloor and backscatter that has the potential to characterize the seafloor. While the uncertainty associated with MBE bathymetry has been well studied, the uncertainty in MBES backscatter measurement has received relatively little attention, hindering the improvements in quantitative analysis of backscatter data. Both acquisition and processing stages can introduce uncertainty in the final seafloor backscatter products. Application of well-established uncertainty quantification principles to seafloor backscatter data is challenging for several reasons: the uncertainty sources are not well known, they vary on a case-by-case basis, and standards do not exist for acquisition and processing. This dissertation focuses on assessing uncertainty in backscatter measurements and is comprised of four separate but related studies that identify and address the challenges of uncertainty quantification of backscatter measurements. The first study (Lucieer et al., 2018) which is presented as background, describes an end users' survey identifying key uses and challenges of backscatter data acquisition and processing. The study identified that consistency and repeatability of backscatter measurements is a major constraint in the use and re-use of backscatter. The second study (Malik et al., 2018), identified the sources of uncertainty and categorized them as significant or insignificant based on various use cases. The most significant sources of uncertainty were found to be inherent statistical fluctuations in the backscatter measurement, calibration uncertainty, seafloor slope and water column absorption estimation. While calibration uncertainty remains the main issue in advancing the quantitative use of the backscatter, the other sources were also shown to cause large uncertainties. These include non-standardized methods used to account for seafloor slope and absorption, and data interpretation errors due to missing background information about the processing procedures. With a comprehensive list of uncertainty sources established, two uncertainty sources, seafloor slope and processing errors, were examined further in the third (Malik, 2019) and the fourth (Malik et al., submitted) study respectively. Seafloor slope corrections are important to correct for both the area insonified and the incidence angle. Both of these corrections are adversely affected if seafloor slope corrections are not applied. Even in cases where the seafloor slope is used, further uncertainty can occur if the highest resolution bathymetry is not used. The results from this study showed that for the purpose of accurate slope corrections, the spatial scale of backscatter data should be selected based on the best available bathymetry. The majority of end users depend on third-party software solutions to process the backscatter data. The fourth study evaluated the output of three commonly used software packages after inputting the same data set and found that there were significant differences in the outputs. This issue was addressed by working closely with software developers to explore options to make the processing chain more transparent. Two intermediate processing stages were proposed and implemented in three commonly used software tools. However, due to proprietary restrictions, it was not possible to know the full details of the software processing packages. Differing outputs likely result, in part, from the different approaches used by the various software packages to read the raw data. Quality assessment and uncertainty quantification of MBES backscatter measurements is still at an early stage and further work is required to develop data acquisition and processing standards to improve consistency in the backscatter acquisition and processing.
590 $a School code: 0141.
650 4 $a Acoustics. $3 879105
650 4 $a Marine geology. $3 3173821
650 4 $a Ocean engineering. $3 660731
650 4 $a Physical oceanography. $3 3168433
653 $a Multibeam echo sounder
653 $a Seafloor backscatter
653 $a Seafloor slope
653 $a Measurement uncertainty
690 $a 0986
690 $a 0547
690 $a 0415
690 $a 0556
710 2 $a University of New Hampshire. $b Natural Resources and Environmental Studies. $3 3282693
773 0 $t Dissertations Abstracts International $g 81-08B.
790 $a 0141
791 $a Ph.D.
792 $a 2019
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=27546403