Backscatter [USGS07]--Offshore of Gaviota Map Area, California

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Frequently anticipated questions:


What does this data set describe?

Title: Backscatter [USGS07]--Offshore of Gaviota Map Area, California
Abstract:
This part of DS 781 presents 2-m-resolution data collected by the U.S. Geological Survey in 2007 for the acoustic-backscatter map of the Offshore of Gaviota Map Area, California. The GeoTiff is included in "Backscatter_[USGS07]_OffshoreGaviota.zip," which is accessible from https://doi.org/10.5066/F7TH8JWJ. These data accompany the pamphlet and map sheets of Johnson, S.Y., Dartnell, P., Cochrane, G.R., Hartwell, S.R., Golden, N.E., Kvitek, R.G., and Davenport, C.W. (S.Y. Johnson and S.A. Cochran, eds.), 2018, California State Waters Map Series—Offshore of Gaviota, California: U.S. Geological Survey Open-File Report 2018–1023, pamphlet 41 p., 9 sheets, scale 1:24,000, https://doi.org/10.3133/ofr20181023.
The acoustic-backscatter map of the Offshore of Gaviota map area in southern California was generated from acoustic-backscatter data collected by the U.S. Geological Survey (USGS) and by Fugro Pelagos Inc. Acoustic mapping was completed between 2007 and 2008 using a combination of 400-kHz Reson 7125, 240-kHz Reson 8101, and 100-kHz Reson 8111 multibeam echosounders, as well as a 234-kHz SEA SWATHplus bathymetric sidescan-sonar system. These mapping missions combined to collect acoustic-backscatter data from about the 10-m isobath to beyond the limit of California's State Waters.
Supplemental_Information:
For additional information CSUMB on Backscatter data online visit <http://seafloor.otterlabs.org>.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
  1. How might this data set be cited?
    Dartnell, Peter, and Kvitek, Rikk G., 2017, Backscatter [USGS07]--Offshore of Gaviota Map Area, California:.

    Online Links:

    This is part of the following larger work.

    Golden, Nadine E., 2013, California State Waters Map Series Data Catalog: Data Series DS 781, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -120.301470
    East_Bounding_Coordinate: -120.193792
    North_Bounding_Coordinate: 34.467806
    South_Bounding_Coordinate: 34.417476
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5898ecd9e4b0efcedb70779e?name=Backscatter_[USGS07]_OffshoreGaviota.jpg&allowOpen=true (JPEG)
    Backscatter collected by the USGS in 2007 in the Offshore of Gaviota map area
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2007
    Ending_Date: 2008
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: GeoTiff
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 2663 x 4883 x 1, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123.00000
      Latitude_of_Projection_Origin: 0.00000
      False_Easting: 500000.0
      False_Northing: 0.00
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 2.0
      Ordinates (y-coordinates) are specified to the nearest 2.0
      Planar coordinates are specified in Meters
      The horizontal datum used is WGS84.
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.00.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    The acoustic-backscatter grid was originally archived as an ESRI grid with the following attributes:
    Cell size = 2.0
    Number of rows = 2663
    Number of columns = 4883
    
    Data type = floating point
    
    Boundary
    Xmin = 748003
    Xmax = 757762
    Ymin = 3812013
    Ymax = 3817335
    
    Statistics
    Minimum value = 44
    Maximum value = 167
    Mean = 99.91071444805012
    Standard deviation = 6.207676788442939
    
    Coordinate system description
    Projection  UTM
    Zone  10
    Datum  WGS84
    Units  meter
    
    Entity_and_Attribute_Detail_Citation: Producer defined

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Peter Dartnell
    • Rikk G. Kvitek
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA
    US

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

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 bathymetric features.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2010 (process 1 of 4)
    During the USGS mapping missions, Real Time Kinematic (RTK) GPS data and measurements of vessel motion (heave, pitch, and roll) were combined in a CodaOctopus F190 attitude-and-position system to produce a high-precision vessel-attitude packet. This packet was transmitted to the acquisition software in real time and combined with instantaneous sound-velocity measurements at the transducer head before each ping. The returned samples were projected to the seafloor using a ray-tracing algorithm that works with previously measured sound-velocity profiles. Statistical filters were applied to the raw samples that discriminate the seafloor returns (soundings) from unintended targets in the water column. The resulting normalized-amplitude values were rescaled to 16-bit and gridded into GeoJPEGs using GRID Processor Software, then imported into a Geographic Information System (GIS) and converted to GRIDs. Person who carried out this activity:
    Pete Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    2885 Mission Street
    Santa Cruz, CA
    USA

    (831) 460-7415 (voice)
    pdartnell@usgs.gov
    Date: 2016 (process 2 of 4)
    During the Fugro Pelagos Inc. mapping missions, an Applanix POS-MV (Position and Orientation System for Marine Vessels) was used to accurately position the vessels during data collection, and it also accounted for vessel motion such as heave, pitch, and roll with navigational input from GPS receivers. Smoothed Best Estimated Trajectory (SBET) files were post-processed from logged POS-MV files. Sound-velocity profiles were collected with an Applied Microsystems (AM) 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) and heave using the post-processed SBET data. Person who carried out this activity:
    Carrie Bretz
    Seafloor Mapping Lab, California State University Monterey Bay
    Projects Manager, GIS & Metadata Supervisor
    100 Campus Center, Bldg 13
    Seaside, CA
    USA

    831.582.4197 (voice)
    carrie_bretz@csumb.edu
    Date: 06-Apr-2018 (process 3 of 4)
    Metadata was modified to add accompanying USGS Open-File Report to the Larger Works section. USGS Thesaurus and keywords were added. Minor typos were corrected. No data information was changed. Person who carried out this activity:
    Susan A Cochran
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Geologist
    2885 Mission Street
    Santa Cruz, CA
    USA

    (831) 460-7545 (voice)
    scochran@usgs.gov
    Date: 31-Aug-2018 (process 4 of 4)
    Information for accompanying Open-File Report was moved from secondary Larger Works section to Abstract and Cross Reference sections. Point of Contact information was updated. Details about different Network Resource Name links was given in the Access Instructions section. Phone number for Metadata Contact was corrected. No data information was changed. Person who carried out this activity:
    Susan A Cochran
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Geologist
    2885 Mission Street
    Santa Cruz, CA
    USA

    (831) 460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Johnson, Samuel Y., Dartnell, Peter, Cochrane, Guy R., Hartwell, Stephen R., Golden, Nadine E., Kvitek, Rikk G., and Davenport, Clifton W., 2018, California State Waters Map Series--Offshore of Gaviota, California: Open-File Report 2018-1023, U.S. Geological Survey, Reston, VA.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Not applicable for raster data.
  2. How accurate are the geographic locations?
    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.
  3. How accurate are the heights or depths?
    Not applicable to acoustic-backscatter imagery.
  4. Where are the gaps in the data? What is missing?
    Complete
  5. How consistent are the relationships among the observations, including topology?
    Unspecified

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    USA

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The .zip file (Backscatter_[USGS07]_OffshoreGaviota.zip) includes the .tif, .tfw, .tif.ovr, .tif.aux.xml, and tif.ColorRamp.SLD files, as well as FGDC-compliant metadata for the for backscatter data collected by the USGS in 2007 in the Offshore of Gaviota map area, California.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    The downloadable data file has been compressed with the "zip" command and can be unzipped with Winzip (or other tool) on Windows systems. To utilize these data, the user must have software capable of uncompressing the WinZip file and importing and viewing an Esri ArcMap TIFF. Users should download the ArcGIS Project File, OffshoreGaviotaGIS.mxd.zip, a compressed (with the "zip" command) version of the ArcMap document (.mxd) that has all the data layers loaded in the table of contents for "Offshore Gaviota" and has all the data symbolized as on the OFR map sheets. Download and save this ArcGIS project file, including all data layers, to the directory the user has created for this GIS.

Who wrote the metadata?

Dates:
Last modified: 31-Aug-2018
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA
US

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/cal_state_waters/Backscatter_[USGS07]_OffshoreGaviota_metadata.faq.html>
Generated by mp version 2.9.49 on Mon Sep 10 17:43:31 2018