Bathymetry and Acoustic Backscatter: Northern Santa Barbara Channel, Southern California

Metadata also available as

Frequently-anticipated questions:

What does this data set describe?

Title:
Bathymetry and Acoustic Backscatter: Northern Santa Barbara Channel, Southern California
Abstract:
This report presents bathymetry and acoustic backscatter data collected in July 2008 in the northern Santa Barbara Channel, California, using a bathymetric sidescan system. The report also presents a summary of the mapping effort as well as Federal Geographic Data Committee (FGDC) metadata. This metadata file describes the backscatter data.
Supplemental_Information:
Information for the related USGS Coastal and Marine Geology data collection field activity, S8-08-SC, is online at <http://walrus.wr.usgs.gov/infobank/s/s808sc/html/s-8-08-sc.meta.html>.

  1. How should this data set be cited?

    United States Geological Survey (USGS), 2010, Bathymetry and Acoustic Backscatter: Northern Santa Barbara Channel, Southern California:.

    Online Links:

    This is part of the following larger work.

    Dartnell, Peter, Finlayson, David, Conrad, James, Cochrane, Guy, and Johnson, Samuel, 2010, Bathymetry and Acoustic Backscatter: Northern Santa Barbara Channel, Southern California: Open-File Report 2009-1289, U.S. Geological Survey, Coastal and Marine Geology Program, Western Coastal and Marine Geology, Menlo Park, CA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -120.5000000
    East_Bounding_Coordinate: -120.0000000
    North_Bounding_Coordinate: 34.50000000
    South_Bounding_Coordinate: 34.25000000

  3. What does it look like?

    <https://pubs.usgs.gov/of/2009/1289/images/usgs2008_mos.pdf> (JPEG)
    Illustration of backscatter imagery

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

    Beginning_Date: 08-Jul-2008
    Ending_Date: 23-Jul-2008
    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: 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 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 backscatter data was originally archived as an ESRI grid with the following attributes: 
    Cell size = 2.0
Number of rows = 6001
Number of columns = 11001

Data type = floating point

Boundary
Xmin = 755999.0
Xmax = 778001.0
Ymin = 3807999.0
Ymax = 3820001.0

Statistics
Minimum value = 12165.5
Maximum value = 58482.87
Mean = 31953.76
Standard deviation = 3448.79

Coordinate system description
Projection  UTM
Zone  10
Datum  NAD83
Units  meters
    These data are published in this report in three different formats with the following attributes, 
    BACKSC.TIFF
Imageformat = TIFF
Image type = grayscale
Image colormap = false
Image compressed = false
Image rotate = false

Image depth = 16
Image bands = 1
Number of columns = 6001
Number of rows = 11001
Pixel size DX = 2.0
Pixel size DY = 2.0

Boundary
Xmin = 755999.0
Xmax = 778001.0
Ymin = 3807999.0
Ymax = 3820001.0

BACKSC.XYZ
XYZ file (x-coord, y-coord, depth) created from the ESRI grid using the command "GRIDPOINT".

BACKSC.ASC
ASCIIRASTER files created from the ESRI grid using the command "GRIDASCII".
    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, Coastal and Marine Geology
    Physical Scientist
    345 Middlefield Rd MS-999
    Menlo Park, CA 94025-3561
    USA

    (650) 329-5460 (voice)
    (650) 329-5411 (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 bathymetry and acoustic backscatter data model.

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: 2009 (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 cm 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 were projected to the seafloor using a ray-tracing algorithm working with the previously measured sound velocity profiles. A series of statistical filters were applied to the raw samples that discriminate the seafloor returns from other unintended targets in the water column. Finally, the processed data were stored, line-by-line in processed trackline files. The individual soundings stored in the processed trackline files were combined into a 2-m resolution rasters in the Grid Processor software. The 2-m binned amplitude values were exported from Grid Processor as an XYZ point cloud. The WGS84 (G1150) ellipsoidal coordinates of the survey were transformed into NAD83 (CORS96) ellipsoidal coordinates using a 7-parameter Helmert transformation available in the CS2CS program in the Proj.4 library (Version 442 for 32-bit Windows). The seven required parameters for the procedure were calculated using an Epoch date of 8 July 2008 according to procedure outlined in Soler and Snay (2004). Finally, the resulting NAD83 (CORS96) elevation postings were transformed into NAVD 1988 using the NOAA VDatum (Version 2.2.4) with the Geoid03 model. A script divided the 2-m binned point cloud into 2 x 2 km tiles. Each tile was gridded using Surfer (Version 9.2.397) and a linear Krigging algorithm and 0.20 cm nugget (the mean standard deviation of all 2-m cells in the survey). Finally, the 2-km tiles were mosaiced into a contiguous raster and converted to an ESRI GRID.

    Person who carried out this activity:

    David Finlayson
    U.S. Geological Survey, Coastal and Marine Geology
    Operational Geologist
    400 Natural Bridges Dr.
    Santa Cruz, CA 95060
    USA

    (831) 427-4757 (voice)
    dfinlayson@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?

    0.05 percent of the water depth.

  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). USGS-authored or produced data and information are in the public domain.

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

    U.S. Geological Survey, Information Services
    345 Middlefield Rd MS-532
    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?


    These data not intended for navigational purposes.
    Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, these data and information are provided with the understanding that they are not guaranteed to be usable, timely, accurate, or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.

    Neither the U.S. Government nor any agency thereof, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any data, software, information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights.

    Trade, firm, or product names and other references to non-USGS products and services are provided for information only and do not constitute endorsement or warranty, express or implied, by the USGS, USDOI, or U.S. Government, as to their suitability, content, usefulness, functioning, completeness, or accuracy.


  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 10-Nov-2008
Metadata author:
Peter Dartnell
U.S. Geological Survey, Coastal and Marine Geology
Physical Scientist
345 Middlefield Rd MS-999
Menlo Park, CA 94025-3561
USA

(650) 329-5460 (voice)
(650) 329-5411 (FAX)
pdartnell@usgs.gov

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

Generated by mp version 2.9.8 on Wed Apr 14 08:12:43 2010