00000nam 2200000zi 4500 9.936229 CaOODSP 20241007095055 m o d f cr |n||||||||| 240402e198903uubccad ot f000 0 eng d CaOODSP eng rda CaOODSP n-cn--- DR52-12/2-1989E-PDF Greening, Michael Victor, 1961- author. Arctic ambient noise beamforming and modelling / by Michael Greening. Sidney, B.C. : JASCO Research Ltd., March 1989 1 online resource (13 pages, 35 unnumbered pages) : illustrations, charts text txt rdacontent computer c rdamedia online resource cr rdacarrier Contractors report series ; 89-28 "Contract Serial No: W7708-8-9910/01-SB"--title page. "Scientific Authority: Dr. P. Zakarauskas, Defence Research Establishment Pacific"--title page. Digitized edition from print [produced by Defence Research and Development Canada]. "The following report details the work completed to date in characterizing the transients contained in the acoustic noise produced from Arctic pack ice. A simple source detection system capable of finding transients with a high signal to noise ratio was used and an average and median number of transients of 4 and 2 respectively were found per 2-minute sample of data. These transients were shown to be vertically directional with a loss at 50-100Hz of approximately 15dB from 5 to 15 degrees from horizontal and a further loss of 10dB from 15 to 90 degrees. This vertical directivity was also shown to increase slightly with frequency. In examining bottom characteristics to aid in modelling the source propagation, sub-bottom layers at 3m and 15 m deep were found. Although exact measurements of bottom roughness were not obtained, it was observed to be acoustically flat for frequencies of up to 2000Hz."--abstract (page 1). Ice Acoustic properties Arctic Ocean. Glace Propriétés acoustiques Arctique, Océan. Technical reports lcgft Rapports techniques rvmgf JASCO Research Ltd., issuing body. Defence Research Establishment Pacific, issuing body. Canada. Department of National Defence. Research and Development Branch, issuing body. Contractors report series ; 89-28. (CaOODSP)9.936079 PDF 1.91 MB https://publications.gc.ca/collections/collection_2024/rddc-drdc/DR52-12-2-1989-eng.pdf CRS 89-28