muskeget_swath_1m.tif: Composite interferometric backscatter mosaic collected by the U.S. Geological Survey in Muskeget Channel, MA, October 2010 (UTM Zone 19N, WGS 84, GeoTIFF, 1-m resolution)

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Frequently anticipated questions:

What does this data set describe?

Title:
muskeget_swath_1m.tif: Composite interferometric backscatter mosaic collected by the U.S. Geological Survey in Muskeget Channel, MA, October 2010 (UTM Zone 19N, WGS 84, GeoTIFF, 1-m resolution)
Abstract:
These data were collected in a collaboration between the Woods Hole Oceanographic Institution and the U.S. Geological Survey (USGS). The primary objective of this program was to collect baseline bathymetry for Muskeget Channel, Massachusetts, and identify areas of morphologic change within and around the channel. Repeat surveys in select areas were collected one month apart to monitor change. These data were collected to support an assessment of the effect on sediment transport that a tidal instream energy conversion facility would have within Muskeget Channel. Accurate data and maps of sea-floor topography are important first steps in monitoring bedform migration, fish habitat, marine resources, and environmental changes due to natural or human impacts. The data include high-resolution bathymetry, acoustic-backscatter intensity, sound velocity in water, and navigation data. These data were collected during two surveys between October 2010 and November 2011 onboard the research vessel (RV) Rafael using an SEA Ltd. SwathPlus interferometric sonar (234 kilohertz). More information about the cruise can be found on the Woods Hole Coastal and Marine Science Center field activity Web page at <http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2010-072-FA>
  1. How should this data set be cited?

    U.S. Geological Survey, 2014, muskeget_swath_1m.tif: Composite interferometric backscatter mosaic collected by the U.S. Geological Survey in Muskeget Channel, MA, October 2010 (UTM Zone 19N, WGS 84, GeoTIFF, 1-m resolution): Open-File Report 2012-1258, U.S. Geological Survey, Reston, VA.

    Online Links:

    This is part of the following larger work.

    Pendleton, Elizabeth A., Denny, Jane F., Danforth, William W., Baldwin, Wayne E., and Irwin, Barry J., 2014, High-Resolution Swath Interferometric Data Collected within Muskegat Channel, Massachusetts: Open-File Report 2012-1258, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -70.505304
    East_Bounding_Coordinate: -70.394974
    North_Bounding_Coordinate: 41.417575
    South_Bounding_Coordinate: 41.291845

  3. What does it look like?

    http://pubs.usgs.gov/of/2012/1258/GIS_catalog/backscatter/BS_thumb.png (PNG)
    gray scale image of backscatter mosaic

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

    Calendar_Date: 12-Oct-2010
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: raster digital data

  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 13812 x 9001 x 1, type Pixel

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 19
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 1.000000
      Ordinates (y-coordinates) are specified to the nearest 1.000000
      Planar coordinates are specified in meters

      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    There are no attributes associated with a GeoTIFF image. Image pixel values contain acoustic reflectivity values normalized to an 24-bit data range. Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values). The background color is set to 0-0-0 and can be turned off without removing data values.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

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?

    Elizabeth A. Pendleton
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543-1598
    USA

    508-548-8700 x2259 (voice)
    508-457-2310 (FAX)
    ependleton@usgs.gov

Why was the data set created?

This GeoTIFF (Tagged Image File Format) contains acoustic backscatter data that were collected in October 2010. These data are used to define the seafloor morphology surrounding Muskeget Channel, Massachusetts

How was the data set created?

  1. From what previous works were the data drawn?

    USGS (source 1 of 1)
    Type_of_Source_Media: disc
    Source_Contribution:
    Backscatter data were acquired with a SEA Swathplus interferometric sonar (234 kHz) mounted on the bow of the R/V Rafael of Woods Hole, MA. The data were acquired with SwathPlus Software (versions: 3.7.10). Tracklines are spaced 70-m apart.

  2. How were the data generated, processed, and modified?

    Date: 2010 (process 1 of 1)
    Swathplus raw backscatter files (.sxr's) were imported into Chesapeake Technology Inc.'s SonarWiz software (version 5). The water-bottom was identified using a user-assisted bottom tracking algorithm. After all the altitudes were correctly defined, an empirical gain normalization (EGN) function for backscatter (Finlayson, 2010) was used to interpolate across data gaps at nadir and enhance the visual display of the data by optimizing the dynamic range of backscatter intensity. SonarWiz was also used to mosaic the lines into a single backscatter file, then export the mosaic to a 1-meter 24-bit GeoTIFF image.

    Person who carried out this activity:

    Elizabeth Pendleton
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2259 (voice)
    (508) 457-2310 (FAX)
    ependleton@usgs.gov

  3. What similar or related data should the user be aware of?

    Poppe, L.J., McMullen, K.Y., Foster, D.S., Blackwood, D.S., Williams, S.J., Ackerman, S.D., Moser, M.S., and Glomb, K.A., 2010, Geological Interpretation of the Sea Floor Offshore of Edgartown, Massachusetts: Open-File Report 2009-1001, U.S. Geological Survey, Reston, VA.

    Online Links:

    Denny, J.F., Danforth, W.W., Foster, D.S., and Sherwood, C.R., 2009, Geophysical Data Collected off the South Shore of Martha's Vineyard, Massachusetts: Open-File Report 2008-1288, U.S. Geological Survey, Reston, VA.

    Online Links:

    Gann, John, Sonar Wiz 5: Chesapeake Technology Inc., Mountain View, CA.

    Online Links:

    Finlayson, David, 2011, SXPTools User Guide: U.S. Geological Survey, Santa Cruz, CA.

    Online Links:

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

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    The navigation for these data was acquired with a Coda Octopus F180 Differential Global Positioning System + Wide Area Augmentation System (DGPS+WAAS); they are accurate to + or - 1 to 2 meters, horizontally. All DGPS data are referenced to WGS 84, and vertical distance between the pole-mounted interferometric sonar head, 0.5m below the sea surface, and the DGPS antenna located on the same pole on the bow of the R/V Rafael, 2.5 m above the sea surface, are corrected.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Interferometric backscatter collected during the first survey of 2010-072-FA were used to create this mosaic. Data from the second survey (on 20101119), which reoccupied lines from the first survey, were not included in this mosaic. Any change in backscatter between surveys 1 and 2 would be nearly negligle in a 1-meter mosaic and outside the scope of the goals of this survey.

  5. How consistent are the relationships among the observations, including topology?

    Although backscatter was not an essential data source for the Muskeget Channel mapping program, they are provided here as supplemental data because they are collected simultaneous with interferometric bathymetry data and are relatively easy to process and release.

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:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.

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

    Elizabeth A. Pendleton
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700x2259 (voice)
    (508) 457-2310 (FAX)
    ependleton@usgs.gov

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

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Neither the U.S. Government, the Department of the Interior, nor the USGS, 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 information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    This zip file contains a GeoTIFF image and world file (.tfw). To utilize these data, the user must have an image viewer, image processing or GIS software package capable of importing a GeoTIFF image and it's assocaited world file.

Who wrote the metadata?

Dates:
Last modified: 06-Jan-2014
Metadata author:
Elizabeth A. Pendleton
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA 02543-1598

(508) 548-8700x2259 (voice)
(508) 457-2310 (FAX)
ependleton@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.9.27 on Mon Jun 09 15:07:20 2014