{
    "tag": 15057,
    "title": "Backscatter D [7125]--Offshore of San Francisco, California",
    "pubdate": "2014",
    "sername": null,
    "series_name": null,
    "issue": "DS 781",
    "publish": null,
    "publisher_name": null,
    "onlink": "https:\/\/cmgds.marine.usgs.gov\/catalog\/pcmsc\/SeriesReports\/DS_DDS\/DS_781\/SanFrancisco\/BackscatterD_7125_2006_OffshoreSanFrancisco_metadata.faq.html",
    "format": null,
    "email": null,
    "descript": "This part of DS 781 presents data for the acoustic-backscatter map of the Offshore of San Francisco map area, California. Backscatter data are provided as separate grids depending on mapping system used and processing techniques. The raster data file is included in \"BackscatterD_7125_2008_OffshoreSanFrancisco.zip,\" which is accessible from https:\/\/pubs.usgs.gov\/ds\/781\/OffshoreSanFrancisco\/data_catalog_OffshoreSanFrancisco.html. These data accompany the pamphlet and map sheets of Cochrane, G.R., Johnson, S.Y., Dartnell, P., Greene, H.G., Erdey, M.D., Golden, N.E., Hartwell, S.R., Endris, C.A., Manson, M.W., Sliter, R.W., Kvitek, R.G., Watt, J.T., Ross, S.L., and Bruns, T.R. (G.R. Cochrane and S.A. Cochran, eds.), 2015, California State Waters Map Series\u2014Offshore of San Francisco, California (ver. 1.1, June 2015): U.S. Geological Survey Open-File Report 2015\u20131068, pamphlet 39 p., 10 sheets, scale 1:24,000, https:\/\/dx.doi.org\/10.3133\/ofr20151068.  The acoustic-backscatter map of the Offshore of San Francisco Map Area, California was generated from backscatter data collected by Fugro Pelagos and by California State University, Monterey Bay (CSUMB). Mapping was completed between 2004 and 2008, 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).",
    "lang": null,
    "journal": null,
    "pwid": null,
    "originator": [
        {
            "name": "Dartnell, Peter",
            "role": "Author"
        },
        {
            "name": "Erdey, Mercedes D.",
            "role": "Author"
        },
        {
            "name": "Kvitek, Rikk G.",
            "role": "Author"
        },
        {
            "name": "Bretz, Carrie K.",
            "role": "Author"
        },
        {
            "name": "Golden, Nadine E.",
            "role": "Author"
        }
    ],
    "index_term": [
        {
            "thcode": 2,
            "code": "474",
            "name": "geospatial datasets",
            "scope": "Collections of related digital information that are geographically referenced."
        },
        {
            "thcode": 2,
            "code": "2046",
            "name": "image mosaics",
            "scope": "Composite images formed by overlapping existing images, typically arranged to achieve greater spatial coverage."
        },
        {
            "thcode": 2,
            "code": "700",
            "name": "maps and atlases",
            "scope": "Representation, usually on a flat surface, of a part or whole of the Earth or other parts of the universe.  Collections of maps linked digitally or bound together in a book are called atlases."
        },
        {
            "thcode": 2,
            "code": "707",
            "name": "marine geophysics",
            "scope": "Branch of earth sciences concerned with the physical processes of the oceans and continental margins.  We include here studies of large bodies of brackish and fresh water, such as lakes and rivers."
        },
        {
            "thcode": 2,
            "code": "2053",
            "name": "sea-floor acoustic reflectivity",
            "scope": "Acoustic energy received by a sonar system, providing a measure of the roughness of the sea floor."
        },
        {
            "thcode": 2,
            "code": "1025",
            "name": "sea-floor characteristics",
            "scope": "Geomorphic features and geographic, compositional, and textural variation in the materials composing the ocean floor. Includes both large-scale structures (such as seamounts and rises) and fine-scale variations in rocks and deposits on the sea floor."
        },
        {
            "thcode": 2,
            "code": "2038",
            "name": "sidescan sonar",
            "scope": "Acoustic technique for creating oblique backscatter imagery of the seafloor or lakebed."
        },
        {
            "thcode": 2,
            "code": "1083",
            "name": "sonar methods",
            "scope": "SOund Navigation And Ranging techniques to detect submerged objects and to determine depths to the bottom of a water body using reflections of sound waves."
        },
        {
            "thcode": 15,
            "code": "008",
            "name": "geoscientificInformation",
            "scope": "Information pertaining to earth sciences, for example geophysical features and processes, geology, minerals, sciences dealing with the composition, structure and origin of the earth's rocks, risks of earthquakes, volcanic activity, landslides, gravity information, soils, permafrost, hydrogeology, groundwater, erosion"
        },
        {
            "thcode": 15,
            "code": "010",
            "name": "imageryBaseMapsEarthCover",
            "scope": "Base maps, for example land\/earth cover, topographic maps, imagery, unclassified images, annotations, digital ortho imagery"
        },
        {
            "thcode": 15,
            "code": "014",
            "name": "oceans",
            "scope": "Features and characteristics of salt water bodies (excluding inland waters), for example tides, tidal waves, coastal information, reefs, maritime, outer continental shelf submerged lands, shoreline"
        },
        {
            "thcode": 23,
            "code": "3",
            "name": "Distributions",
            "scope": "Locations or patterns of a feature of interest across space and (or) time. These data can include point data, lines, polygons, and temporal data at any scale relevant to CMSP and can be produced by observation, interpolation, or modeling. Distributions can also include maps or statistics of climatology, the environmental values that are expected to be observed at the present time."
        },
        {
            "thcode": 23,
            "code": "21",
            "name": "Physical Habitats and Geomorphology",
            "scope": "Includes measures of the geologic and structural characteristics of the coast or sea floor, such as the features defined in the Geoform Component of CMECS. Distributions are detailed topographic and bathymetric maps, geolocated photographs, or sea-floor descriptions; Distributions includes maps that interpret observations to categorize areas on the basis of geoform types such as those in CMECS. Assessment types include evaluations of ecological or human use value and can include models that project environmental or economic effects of erosion, climate change, dredging, and other stressors. Predictions are the results of models or projections of future distributions, values, or ecological impacts of physical habitats, including predicted changes due to natural and human forces; they are also from scenario-based models of resource losses, gains, or impacts on ecological or economic values under different management strategies (for example, mining, removal, relocation, or the building of structures)."
        },
        {
            "thcode": 61,
            "code": "173",
            "name": "seabed",
            "scope": "the floor of a sea or ocean."
        },
        {
            "thcode": 61,
            "code": "403",
            "name": "sidescan sonar",
            "scope": "acoustic technique for producing oblique imagery of the sea floor."
        },
        {
            "thcode": 62,
            "code": "GC-044",
            "name": "Continental\/Island Shelf",
            "scope": "Physiographic Setting: That part of the continental margin that is between the shoreline and the continental slope (or a depth or 200 meters when there is no noticeable continental slope); it is characterized by its very gentle slope of 0.1\u00b0. ..."
        },
        {
            "thcode": 62,
            "code": "AS-013",
            "name": "Marine Nearshore Subtidal",
            "scope": "Tidal Zone: The substrate is generally continuously submerged in this zone and includes those areas below MLLW."
        },
        {
            "thcode": 62,
            "code": "AS-016",
            "name": "Marine Offshore Subtidal",
            "scope": "Tidal Zone: The substrate is subtidal and continuously submerged in this zone and includes those areas below MLLW."
        },
        {
            "thcode": 62,
            "code": "SC-026",
            "name": "Rock Substrate",
            "scope": "Substrate Class: Igneous, metamorphic, or sedimentary rock with particle sizes greater than or equal to 4.0 meters (4,096 millimeters) in any dimension that cover 50% or greater of the Geologic Substrate surface."
        },
        {
            "thcode": 62,
            "code": "GC-037",
            "name": "Transform Continental Margin",
            "scope": "Tectonic Setting: A feature defined by the transform fault that develops during continental rifting. ..."
        },
        {
            "thcode": 62,
            "code": "SC-029",
            "name": "Unconsolidated Mineral Substrate",
            "scope": "Substrate Class: Geologic Substrates with less than 50% cover of Rock Substrate. ..."
        }
    ],
    "place_term": [],
    "image": [
        {
            "name": "https:\/\/pubs.usgs.gov\/ds\/781\/OffshoreSanFrancisco\/images\/BackscatterD_7125_2006_OffshoreSanFrancisco.jpg",
            "description": "Acoustic backscatter imagery of Offshore San Francisco map area."
        }
    ],
    "fan": []
}