{"accessLevel": "public", "bureauCode": ["010:12"], "contactPoint": {"@type": "vcard:Contact", "fn": "PCMSC Science Data Coordinator", "hasEmail": "mailto:pcmsc_data@usgs.gov"}, "description": "This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Pacifica map area, California. Backscatter data are provided as two separate grids depending on mapping system. The raster data files are included in \"Backscatter7125_OffshorePacifica.zip,\" which is accessible from https://pubs.usgs.gov/ds/781/OffshorePacifica/data_catalog_OffshorePacifica.html. These data accompany the pamphlet and map sheets of Edwards, B.D., Phillips, E.L., Dartnell, P., Greene, H.G., Bretz, C.K., Kvitek, R.G., Hartwell, S.R., Johnson, S.Y., Cochrane, G.R., Dieter, B.E., Sliter, R.W., Ross, S.L., Golden, N.E., Watt, J.T., Chin, J.L., Erdey, M.D., Krigsman, L.M., Manson, M.W., and Endris, C.A. (S.A. Cochran and B.D. Edwards, eds.), 2014, California State Waters Map Series\u2014Offshore of Pacifica, California: U.S. Geological Survey Open-File Report 2014\u20131260, pamphlet 38 p., 10 sheets, scale 1:24,000, https://doi.org/10.3133/ofr20141260.\nThe acoustic-backscatter map of the Offshore of Pacifica, California was generated from backscatter data collected by Fugro Pelagos and by California State University, Monterey Bay (CSUMB). Mapping was completed between 2005 and 2007, using a combination of 400-kHz Reson 7125 and 244-kHz Reson 8101 multibeam echosounders. Within the final imagery, brighter tones indicate higher backscatter intensity, and darker tones indicate lower backscatter intensity. The intensity represents a complex interaction between the acoustic pulse and the seafloor, as well as characteristics within the shallow subsurface, providing a general indication of seafloor texture and composition. Backscatter intensity depends on the acoustic source level; the frequency used to image the seafloor; the grazing angle; the composition and character of the seafloor, including grain size, water content, bulk density, and seafloor roughness; and some biological cover. Harder and rougher bottom types such as rocky outcrops or coarse sediment typically return stronger intensities (high backscatter, lighter tones), whereas softer bottom types such as fine sediment return weaker intensities (low backscatter, darker tones).", "distribution": [{"@type": "dcat:Distribution", "description": "The metadata original format", "downloadURL": "https://data.usgs.gov/datacatalog/metadata/USGS.0ce7f53d-8404-4c12-a9d9-0d01132fc152.xml", "format": "XML", "mediaType": "text/xml", "title": "Original Metadata"}, {"@type": "dcat:Distribution", "accessURL": "https://pubs.usgs.gov/ds/781/OffshorePacifica/data_catalog_OffshorePacifica.html", "description": "Landing page for access to the data", "format": "XML", "mediaType": "application/http", "title": "Digital Data"}], "identifier": "http://datainventory.doi.gov/id/dataset/USGS_0ce7f53d-8404-4c12-a9d9-0d01132fc152", "keyword": ["sonar methods", "distributions", "imageryBaseMapsEarthCover", "Coastal and Marine Hazards and Resources Program", "geospatial datasets", "seabed", "Pacifica", "maps and atlases", "Pacific Ocean", "U.S. Geological Survey", "San Mateo County", "Acoustic Reflectivity", "Rockaway Beach", "Marine Nearshore Subtidal", "USGS", "CMHRP", "USGS:0ce7f53d-8404-4c12-a9d9-0d01132fc152", "sea-floor acoustic reflectivity", "State of California", "Transform Continental Margin", "sea-floor characteristics", "marine geophysics", "Northern California Ecoregion", "Marine Offshore Subtidal", "Continental/Island Shelf", "image mosaics", "oceans", "sidescan sonar", "Pacific Coastal and Marine Science Center", "geoscientificInformation", "Rock Substrate", "PCMSC", "Unconsolidated Mineral Substrate", "physical habitats and geomorphology"], "modified": "2023-02-24T00:00:00Z", "publisher": {"@type": "org:Organization", "name": "U.S. Geological Survey"}, "spatial": "-122.65, 37.54, -122.40, 37.70", "theme": ["geospatial"], "title": "BackscatterB [7125]--Offshore Pacifica, California"}