Peter DartnellRikk G. Kvitek2014Backscatter A [8101]--Offshore of Fort Ross, California1.0GeoTiffSamuel Y. JohnsonPeter DartnellNadine E. GoldenStephan R. HartwellH. Gary GreeneMercedes D. ErdeyGuy R. CochraneJanet L. WattRikk G. KvitekMichael W. MansonCharles A. EndrisBryan E. DieterLisa M. KrigsmanRay W. SliterErik N. LoweJohn L. Chin2015California State Waters Map Series—Offshore of Fort Ross, CaliforniamapOpen-File ReportOFR 2015–1211Reston, VAU.S. Geological Surveyhttps://dx.doi.org/10.3133/ofr20151211Nadine E. Golden2014California State Waters Map Series Data CatalogdatabaseData SeriesDS 781Reston, VAU.S. Geological Surveyhttps://pubs.usgs.gov/ds/781/https://www.sciencebase.gov/arcgis/rest/services/Catalog/555cdb07e4b0a92fa7eb81c5/MapServerhttps://www.sciencebase.gov/arcgis/services/Catalog/555cdb07e4b0a92fa7eb81c5/MapServer/WMSServer?request=GetCapabilities&service=WMSThis part of DS 781 presents data for the acoustic-backscatter map of the Offshore of Fort Ross map area, California. Backscatter data are provided as separate grids depending on mapping system or processing method. The raster data file is included in "BackscatterA_8101_OffshoreFortRoss.zip", which is accessible from https://pubs.usgs.gov/ds/781/OffshoreFortRoss/data_catalog_OffshoreFortRoss.html.
The acoustic-backscatter map of the Offshore of Fort Ross map area, California, was generated from backscatter data collected by California State University, Monterey Bay (CSUMB) and by Fugro Pelagos. Mapping was completed between 2007 and 2010, using a combination of 200-kHz and 400-kHz Reson 7125, and 244-kHz Reson 8101 multibeam echosounders, as well as 468-kHz SEA SWATHPlus interferometric system. These mapping missions combined to collect backscatter data from about the 10-m isobath to beyond the 3-nautical-mile limit of California State Waters. Within the acoustic-backscatter 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). These data are not intended for navigational purposes.These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify seafloor features. This information is not intended for navigational purposes.None20072010ground conditionAs needed-123.30-123.1038.5638.40Global Change Master Directory (GCMD)Oceans > Bathymetry/SeafloorTopography > BathymetryOceans > Bathymetry/SeafloorTopography > Seafloor TopographyISO 19115 Topic CategorygeoscientificInformationenvironmentoceansimageryBaseMapsEarthCoverGeneralSeafloor CharacterFisheriesEcosystemMultibeamGeologyBathymetryBackscatterIntensityOcean Floor TopographyU.S. Geological SurveyUSGSPacific Coastal and Marine Science CenterCMGPGeographic Names Information System (GNIS)Pacific OceanState of CaliforniaSonoma CountyFort RossJennerRussian RiverIf physical samples or materials are available, constraints on their on-site access are described in "WR CMG Sample Distribution Policy" at URL: https://walrus.wr.usgs.gov/infobank/programs/html/main/sample-dist-policy.htmlThis information is not intended for navigational purposes.
Read and fully comprehend the metadata prior to data use. Uses of these
data should not violate the spatial resolution of the data. Where
these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data.
Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.
This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.Peter DartnellU.S. Geological Survey,
Pacific Coastal and Marine Science CenterPhysical Scientistmailing and physical address400 Natural Bridges Dr.Santa CruzCA95060-5792USA(831) 460-7415(831) 427-4709pdartnell@usgs.govhttps://pubs.usgs.gov/ds/781/OffshoreFortRoss/images/BackscatterA_8101_OffshoreFortRoss.jpgAcoustic backscatter imagery of the Offshore of Fort Ross map area.JPEGNot applicable for raster data.UnspecifiedCompleteHorizontal_Positional_Accuracy_Report: Estimated to be no less than 2 m, owing to water depth and total propagated uncertainties of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data processing that includes sounding cleaning, gridding, and datum transformations.Not ApplicableDuring the Fugro Pelagos and CSUMB mapping missions, an Applanix Position and Motion Compensation System for Marine Vessels (POS/MV, 320, v4) was used to accurately position the vessels during data collection, and it also accounted for vessel's motion such as heave, pitch, and roll (position accuracy, +/-2 m; pitch, roll, and heading accuracy, +/-0.02; heave accuracy, +/-5%, or 5 cm). KGPS altitude data (Fugro Pelagos, StarFix HP & XP units; CSUMB, NavCom 2050) were used to account for tide cycle fluctuations and sound velocity profiles were collected with an Applied Microsystems SVPlus sound velocimeter. Soundings were corrected for vessel motion using the Applanix POS/MV data, for variations in water-column sound velocity using the AM SVPlus data, and for variations in water height (tides) using vertical-position data from the KGPS receivers. The multibeam backscatter data then were processed using Geocoder (Fugro Pelagos Modified Test Release 16) or Geocoder within Caris HIPS and SIPS. Within Geocoder, the backscatter intensities were radiometrically corrected (including despeckling and angle-varying gain adjustments), and the position of each acoustic sample was geometrically corrected for slant range. This processed imagery was stored as Georeferenced, Backscatter Rasters (GeoBARs). After GeoBARs were created for each line, they were mosaicked into 1-m or 2-m resolution images. Overlap between parallel lines was resolved using a priority table based on the distance of each sample from the ship track, with samples closest to- and furthest from- the ship track given the lowest priority. An anti-aliasing algorithm was also applied. The SWATHPlus backscatter data were processed using SXPTools v 2.0 (David Finlayson, USGS) and SEA Grid Processor v 3.02.19.0. SXPTools is a collection of command line programs that are used to enhance the quality of SEA SWATHplus interferometric sidescan sonar data. The programs are primarily focused on enhancing the backscatter quality, but there is some benefit to the bathymetry as well. The SXPTools sxpegn command was used to equalize the backscatter amplitude, and the sxpmagic command was used to help fill gaps and remove artifacts near nadir. After processing with SXPTools, lines were imported into Grid Processor and mosaicked into 1-m or 2-m resolution image. The mosaic image for each survey block was exported as a GeoJpeg from Grid Processor and converted to GeoTiff using Adobe Photoshop or GIMP. In some cases memory limitations in Grid Processor required tiling a block mosaic into 2 or more sub-mosaics.2010Carrie BretzSeafloor Mapping Lab, California State University Monterey BayProjects Manager, GIS; Metadata Supervisormailing and physical address100 Campus Center, Bldg 13SeasideCA93955USA(831) 582-4197carrie_bretz@csumb.eduCalifornia Seafloor Mapping Project 1- or 2-m resolution backscatter imagery within this map were downloaded from California State University, Monterey Bay, Seafloor Mapping Lab (http://seafloor.csumb.edu/SFMLwebDATA.htm) and converted to grids. Backscatter grids of similar mapping systems were merged in a GIS and clipped to the boundary of the map area. Grids from different mapping systems were not merged together due to different mapping frequencies and processing techniques. Grids were projected horizontally to WGS-84 using ESRI ArcTools.2013Pete DartnellU.S. Geological Survey, Pacific Coastal and Marine Science CenterPhysical Scientistmailing and physical address400 Natural Bridges Dr.Santa CruzCA95060-5792USA(831) 460-7415pdartnell@usgs.govRasterGrid CellUniversal Transverse Mercator100.9996-123.000000.00000500000.00.00coordinate pair2.02.0MetersWGS84WGS846378137.00 meters298.257223563The merged Reson 8101 acoustic-backscatter grid was originally archived as an ESRI grid with the following attributes:
>Cell size = 2.0
>Number of rows = 8900
>Number of columns = 8885
>
>Data type = unsigned integer
>
>Boundary
>Xmin = 473300
>Xmax = 491070
>Ymin = 4249780
>Ymax = 4267580
>
>Statistics
>Minimum value = 0
>Maximum value = 254
>Mean = 124.90
>Standard deviation = 24.62
>
>Coordinate system description
>Projection UTM
>Zone 10
>Datum WGS84
>Units meter
The merged Reson 7125 acoustic-backscatter grid was originally archived as an ESRI grid with the following attributes:
>Cell size = 2.0
>Number of rows = 8900
>Number of columns = 8885
>
>Data type = unsigned integer
>
>Boundary
>Xmin = 473300
>Xmax = 491070
>Ymin = 4249780
>Ymax = 4267580
>
>Statistics
>Minimum value = 0
>Maximum value = 254
>Mean = 96.41
>Standard deviation = 27.76
>
>Coordinate system description
>Projection UTM
>Zone 10
>Datum WGS84
>Units meter
The merged SWATHPlus acoustic-backscatter grid was originally archived as an ESRI grid with the following attributes:
>Cell size = 2.0
>Number of rows = 8900
>Number of columns = 8885
>
>Data type = unsigned integer
>
>Boundary
>Xmin = 473300
>Xmax = 491070
>Ymin = 4249780
>Ymax = 4267580
>
>Statistics
>Minimum value = 1
>Maximum value = 254
>Mean = 112.70
>Standard deviation = 41.48
>
>Coordinate system description
>Projection UTM
>Zone 10
>Datum WGS84
>Units meternone2014042820140923Peter DartnellU.S. Geological Survey, Pacific Coastal and Marine Science CenterPhysical Scientistmailing and physical address400 Natural Bridges Dr.Santa CruzCA95060-5792USA(831) 460-7415(831) 427-4709pdartnell@usgs.govContent Standard for Digital Geospatial Metadata
("CSDGM version 2")FGDC-STD-001-1998universal time