Acoustic Backscatter - Outer Mainland Shelf, Eastern Santa Barbara Channel, California

Metadata also available as

Frequently anticipated questions:

What does this data set describe?

Title:
Acoustic Backscatter - Outer Mainland Shelf, Eastern Santa Barbara Channel, California
Abstract:
The U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center in cooperation with the Bureau of Ocean Energy Management (BOEM) collected high-resolution bathymetry and acoustic backscatter data along the outer mainland shelf in the eastern Santa Barbara Channel, southern California. These data were collected in July 2010 and July 2011 using a bathymetric sidescan system. This report provides the bathymetry and backscatter data along with a summary of the mapping efforts and Federal Geographic Data Committee (FGDC) metadata. This metadata file describes the acoustic backscatter data.
Supplemental_Information:
Information for the related USGS Pacific Coastal and Marine Science Center data collection field activities, S-14-10-SC and S-08-11-SC, online at <http://walrus.wr.usgs.gov/infobank/s/s1410sc/html/s-14-10-sc.meta.html> and <http://walrus.wr.usgs.gov/infobank/s/s0811sc/html/s-08-11-sc.meta.html>.

  1. How should this data set be cited?

    United States Geological Survey (USGS), 2012, Acoustic Backscatter - Outer Mainland Shelf, Eastern Santa Barbara Channel, California:.

    Online Links:

    This is part of the following larger work.

    Dartnell, Peter, Ritchie, Andy, Finlayson, David, Cochrane, Guy, and Erdey, Mercedes, 2012, Bathymetry and Acoustic Backscatter - Outer Mainland Shelf, Eastern Santa Barbara Channel, California: Data Series 702, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -119.7500000
    East_Bounding_Coordinate: -119.2500000
    North_Bounding_Coordinate: 34.37000000
    South_Bounding_Coordinate: 34.10000000

  3. What does it look like?

    <https://pubs.usgs.gov/ds/702/figures/backscatter_map.gif> (GIF)
    Acoustic backscatter imagery of the eastern Santa Barbara Channel region

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 28-Jun-2010
    Ending_Date: 26-Jul-2011
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Raster

  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, 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: 11
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -117.00000
      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 NAD83.
      The ellipsoid used is NAVD88.
      The semi-major axis of the ellipsoid used is 6378137.00 meters.
      The flattening of the ellipsoid used is 1/0.003352811.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    The complete 2010 - 2011 acoustic backscatter data was originally archived as an ESRI grid with the following attributes: 
    Cell size = 2.0
Number of rows = 14,271
Number of columns = 21,553

Data type = floating point

Boundary
Xmin = 247426.13
Xmax = 290542.13
Ymin = 3777642.27
Ymax = 3806184.27

Statistics
Minimum value = 0
Maximum value = 65535
Mean = 2712641
Standard deviation = 11370.68

Coordinate system description
Projection  UTM
Zone  11
Datum  NAD83
Units  meter
    Entity_and_Attribute_Detail_Citation: none

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Peter Dartnell
    U.S. Geological Survey, Pacifc Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridge Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    (831) 427-4709 (FAX)
    pdartnell@usgs.gov

Why was the data set created?

These data are intended for science researchers, students, policy makers, and the general public. The data can be used with geographic information systems (GIS) or other software to display the acoustic backscatter data. These data are not intended for navigational purposes.

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: 2012 (process 1 of 1)
    The bathymetry and backscatter data were collected using 234.5 kHz SEA (AP) Ltd. SWATHplus-M phase-differencing sidescan sonar aboard the USGS R/V Parke Snavely. The survey vessel was equipped with a CodaOctopus F190 attitude and position system. This system combines Real Time Kinematic (RTK) Global Positioning System (GPS) data (2 centimeter error ellipse) with inertial motion measurements so that high-precision position and attitude corrections are fed in real-time to the sonar acquisition equipment. Up to 10 pings per second are transmitted with each ping consisting of 2048 samples per side (port and starboard). The returned samples are projected to the seafloor using a ray-tracing algorithm working with the previously measured sound velocity profiles. A series of statistical filters are applied to the raw samples that discriminate the seafloor returns from other unintended targets in the water column. The raw 16-bit backscatter data recorded simultaneously with bathymetry by the SWATHplus was georeferenced and gain-normalized by the program SXPEGN, software written by the USGS to enhance the backscatter of the SWATHplus system. The program normalizes for time-varying signal loss and beam directivity differences. The resulting normalized amplitude values are re-scaled to 16-bit, and gridded into GeoJPEGS using GRID Processor Software supplied by SEA. The images were converted to geoTIFF images using ESRI GIS software.

    Person who carried out this activity:

    Pete Dartnell
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Physical Scientist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060-5792
    USA

    (831) 460-7415 (voice)
    pdartnell@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?

    Not applicable for raster data.

  2. How accurate are the geographic locations?

    0.5 meters

  3. How accurate are the heights or depths?

    Not applicable

  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:

Please recognize the U.S. Geological Survey (USGS) and the Bureau of Ocean Energy Management (BOEM). USGS-authored or produced data and information are in the public domain.
This 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.

  1. Who distributes the data set? (Distributor 1 of 1)

    U.S. Geological Survey
    345 Middlefield Rd
    Menlo Park, CA 94025-3561
    USA

    (650) 329-4309 (voice)

  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?


    This information is not intended for navigational purposes.
    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.
    Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.


  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 25-Mar-2012
Last Reviewed: 03-Apr-2012
Metadata author:
Peter Dartnell
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Physical Scientist
400 Natural Bridges Dr.
Santa Cruz, CA 95060-5792
USA

(831) 460-7415 (voice)
(831) 427-4709 (FAX)
pdartnell@usgs.gov

Metadata standard:
Content Standard for Digital Geospatial Metadata ("CSDGM version 2") (FGDC-STD-001-1998)

Generated by mp version 2.9.13 on Thu Jul 26 10:56:14 2012