Acoustic backscatter data collected in 2007 from the San Miguel Passage in the Channel Islands, California

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Frequently anticipated questions:

What does this data set describe?

Title:
Acoustic backscatter data collected in 2007 from the San Miguel Passage in the Channel Islands, California
Abstract:
This portion of the data release presents acoustic backscatter data from the San Miguel Passage, in the Channel Islands, California. The data were collected in August 2007 by the U.S. Geological Survey, Pacific Coastal and Marine Science Center (USGS, PCMSC) using a 234.5 kHz SEA (AP) Ltd. SWATHplus-M phase-differencing sidescan sonar mounted on the NOAA, Channel Islands National Marine Sanctuary R/V Shearwater as part of the research cruise S-2-07-SC. Data were collected in water depths up to 89 meters. The San Miguel Passage is within the Channel Islands National Marine Sanctuary and is the body of water between the two western-most islands of the chain - Santa Rosa and San Miguel Islands. The data were processed at the USGS, PCMSC to create a 2-meter resolution TIFF raster, presented here.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=S207SC
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Cochrane, Guy R., Finlayson, David P., and Dailey, Evan T., 2018, Acoustic backscatter data collected in 2007 from the San Miguel Passage in the Channel Islands, California: data release DOI:10.5066/F78G8HVC, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Cochrane, Guy R., Finlayson, David P., and Dailey, Evan T., 2018, Bathymetry and acoustic backscatter data collected in 2007 from the San Miguel Passage in the Channel Islands, California: data release DOI:10.5066/F78G8HVC, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -120.312
    East_Bounding_Coordinate: -120.182
    North_Bounding_Coordinate: 34.018
    South_Bounding_Coordinate: 33.895
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5b4f9061e4b06a6dd18444a0?name=Backscatter_SanMiguelPassage.jpg&allowOpen=true (JPG)
    Image map of study area with backscatter intensity raster
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 06-Aug-2007
    Ending_Date: 18-Aug-2007
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: TIFF
  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 6239 x 5654, 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: -123.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      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 D_North_American_1983.
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: MLLW
      Altitude_Resolution: 0.1
      Altitude_Distance_Units: Meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Attribute table
    Table containing attribute information associated with the dataset (Source: U.S. Geological Survey)
    Value
    Backscatter intensity (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:255
    Units:Backscatter intensity value

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Guy R. Cochrane
    • David P. Finlayson
    • Evan T. Dailey
  2. Who also contributed to the data set?
    Data collection was funded by U.S. Geological Survey
  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

    831-460-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

These data were collected to characterize seafloor substrate types in the nearshore waters southwest of Santa Rosa Island in the Channel Islands National Marine Sanctuary.

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: 31-Aug-2007 (process 1 of 4)
    Data Collection: Bathymetry and acoustic-backscatter data were collected in 2007 using a 234.5 kHz SEA (AP) Ltd. SWATHplus-M phase-differencing sidescan sonar, mounted on the NOAA CINMS R/V Shearwater. Data were acquired and processed onboard using SEA Swath Processor (version 2.05) and SEA Grid Processor (version 2.05). Sound velocity profiles (SVPs) were collected with an Applied Micro Systems, SvPlus. The survey vessel was equipped with a dual antenna GPS compass and inertial attitude sensor: F180 Control Software (version 2.04), and the navigation application YONAV2 (version 1.19). GPS navigation data were post-processed with GrafNav (version 7.8) from Waypoint Navigation (NovAtel). Navigation data were processed in both forward and reverse.
    Date: 31-Aug-2007 (process 2 of 4)
    Data Gridding: The survey line files were imported into Caris HIPS and SIPS software (version 7.1.2). Bathymetry data were processed, filtered, and gridded into a 2-meter resolution base surface using the swath angle method. Backscatter data were processed using Caris mosaic module using the SIPS, sidescan engine. The base surface and backscatter mosaic were exported as a TIFF files in UTM-10 coordinates referenced to the NAD83 ellipsoid. The TIFF files were imported into a Geographic Information System (Esri, ArcMap) and converted to a grid. The grid was converted to an 8-bit raster in ArcMap and exported as a TIFF file with a TFW file defining the data’s geographic location and coordinate system.
    Date: 19-Oct-2020 (process 3 of 4)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 13-Oct-2021 (process 4 of 4)
    Performed minor edits to the metadata to correct typos. No data were changed Person who carried out this activity:
    U.S. Geological Survey
    Attn: Susan A. Cochran
    Geologist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?

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

  1. How well have the observations been checked?
    No formal attribute accuracy tests were conducted. See spatial accuracy for vertical and horizontal accuracies.
  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 backscatter imagery.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    All data fall within expected ranges.

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 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

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? These data are available in TIFF format (Backscatter_SanMiguelPassage_NAD83-UTM10N.tif) contained in a single zip file which also includes a TIFF world file (.tfw), CSDGM FGDC-compliant metadata, and a browse image map of the data (.jpg).
  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?
    These data can be viewed with Esri ArcGIS software.

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2021
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-460-4747 (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/DataReleases/ScienceBase/DR_F78G8HVC/Backscatter_SanMiguelPassage_NAD83UTM10N_meta.faq.html>
Generated by mp version 2.9.50 on Thu Oct 14 14:47:20 2021