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dc.contributor.authorSwift, Stephen A.  Concept link
dc.contributor.authorLittle, William S.  Concept link
dc.contributor.authorStephen, Ralph A.  Concept link
dc.date.accessioned2017-10-26T20:43:04Z
dc.date.available2017-10-26T20:43:04Z
dc.date.issued1995-05
dc.identifier.urihttps://hdl.handle.net/1912/9326
dc.description.abstractA study was carried out to quantify the level of numerical noise in numerical scattering chamber (NSC) calculations and to compare these noise levels with signal levels of body waves, interface waves and ambient noise. The amplitudes of signal and noise in snapshots from the numerical scattering chamber were quantified at 50 and 65 periods for a few reference models. Models with homogeneous subseafloor structure were studied to determine the level of numerical noise; models with a wavenumber-correlation length product of one were examined to determine signal levels. Models were run with both Higdon and telegraph equation absorbing boundaries since the numerical noise within the grid depends on the boundary formulation. Amplitudes were measured along data traces obtained at a grid depth of 3.33 λw and at the seafloor. Forward traveling head waves had typical amplitudes of ±125 but may reached ±250 near the direct wave. Diffraction amplitudes were observed up to ±300. Stoneley wave amplitudes ranged from ±800 up to ±20,000. Numerical noise levels were less than ±25 in most areas of the water and less than ±350 along most of the seafloor. Regardless of the absorbing boundary type, however, there was a region of noise extending up to 15 λw behind the first seafloor reflection at 3.33 λw in which noise levels range from ±100 up to ±600. In this region it is difficult to resolve signal from systematic numerical noise.en_US
dc.description.sponsorshipThis work was carried out under ONR Grant #N00014-90-J-1493en_US
dc.language.isoen_USen_US
dc.publisherWoods Hole Oceanographic Institutionen_US
dc.relation.ispartofseriesWHOI Technical Memorandaen_US
dc.relation.ispartofseriesWHOI-01-95en_US
dc.subjectUnderwater acousticsen_US
dc.subjectScatteringen_US
dc.titleSignal and noise levels in numerical scattering chamber snapshotsen_US
dc.typeWorking Paperen_US
dc.identifier.doi10.1575/1912/9326


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