GeoTIFF image of the backscatter intensity of the sea floor of the Sandy Hook artificial reef (2-m resolution, Mercator, WGS 84)

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Frequently anticipated questions:

What does this data set describe?

Title:
GeoTIFF image of the backscatter intensity of the sea floor of the Sandy Hook artificial reef (2-m resolution, Mercator, WGS 84)
Abstract:
The Sandy Hook artificial reef, located on the sea floor offshore of Sandy Hook, New Jersey was built to create habitat for marine life. The reef was created by the placement of heavy materials on the sea floor; ninety-five percent of the material in the Sandy Hook reef is rock. In 2000, the U.S. Geological Survey surveyed the area using a Simrad EM1000 multibeam echosounder mounted on the Canadian Coast Guard (CCG) ship Frederick G. Creed. The purpose of this multibeam survey, done in cooperation with the U.S. Army Corps of Engineers when the Creed was in the New York region in April 2000, was to map the bathymetry and backscatter intensity of the sea floor in the area of the Sandy Hook artificial reef. The collected data from this cruise are bathymetry, backscatter intensity, and navigation trackline.
Supplemental_Information:
Other datasets from the 2000 survey of the Sandy Hook artificial reef may be found in Butman and others (2017) (see larger work citation). For more information on the field activity that collected these data, see the field activity page https://cmgds.marine.usgs.gov/fan_info.php?fa=2000-015-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, and U.S. Army Corps of Engineers, 2017, GeoTIFF image of the backscatter intensity of the sea floor of the Sandy Hook artificial reef (2-m resolution, Mercator, WGS 84): data release DOI:10.5066/F74F1PNH, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Butman, Bradford, Danforth, William W., John E. Hughes Clarke, and Signell, Richard P., 2017, Bathymetry and backscatter intensity of the sea floor of the Sandy Hook artificial reef, offshore of New Jersey: data release DOI:10.5066/F74F1PNH, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Butman, Bradford, Danforth, W.W., Clarke, J.E.H., and Signell, R.P., 2017, Bathymetry and backscatter intensity of the sea floor of the Sandy Hook artificial reef, offshore of New Jersey: U.S. Geological Survey data release, https://doi.org/10.5066/F74F1PNH.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.946685
    East_Bounding_Coordinate: -73.928370
    North_Bounding_Coordinate: 40.396680
    South_Bounding_Coordinate: 40.340089
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/59b2b96ae4b020cdf7dc1416?name=shreef_backi2m_browsegraphic.jpg (JPEG)
    Browse graphic of the backscatter intensity of the sea floor of the Sandy Hook artificial reef.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 23-Apr-2000
    Ending_Date: 24-Apr-2000
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: remote-sensing image
  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 3536 x 1211 x 1, type Pixel
    2. What coordinate system is used to represent geographic features?
      The map projection used is Mercator.
      Projection parameters:
      Standard_Parallel: 40.000000
      Longitude_of_Central_Meridian: -75.000000
      False_Easting: 0.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 2.000000
      Ordinates (y-coordinates) are specified to the nearest 2.000000
      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:
    Backscatter intensity, the intensity of the acoustic return from the sea floor from the multibeam system, is a function of the properties of the surficial sediments and of the bottom roughness. Generally high backscatter intensity (strong return), shown as light gray tones, is associated with rock or coarse-grained sediment, and low backscatter intensity (weak return), shown as dark gray tones, with fine-grained sediments. However, the micro-topography, such as ripples, burrows, and benthic populations also affect the reflectivity of the sea floor. Direct observations, using bottom photography or video, and surface samples, are needed to verify interpretations of the backscatter intensity data. The backscatter data have a weak striping that runs parallel to the ship trackline. Some of the striping is the result of poor data return at nadir that appears as evenly-spaced thin speckled lines. Backscatter intensity is shown as an 8-bit (0-255) grayscale image; 255 is no data.
    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)
    • U.S. Geological Survey
    • U.S. Army Corps of Engineers
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Bradford Butman
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x 2212 (voice)
    bbutman@usgs.gov

Why was the data set created?

The GeoTIFF image of backscatter intensity provides qualitative information on the sediment texture and roughness of the sea floor. Backscatter intensity, a measure of the strength of the acoustic return from the sea floor, is a function of the properties of the surficial sediments and of the bottom roughness. Generally high backscatter intensity (strong return), shown as light gray tones, is associated with rock or coarse-grained sediment, and low backscatter intensity (weak return), shown as dark gray tones, with fine-grained sediments.

How was the data set created?

  1. From what previous works were the data drawn?
    none (source 1 of 1)
    Service, Canadian Hydrographic, Danforth, William W., and John E. Hughes Clarke, Unpublished Material, Raw multibeam data.

    Type_of_Source_Media: disc
    Source_Contribution:
    The multibeam data were collected with a Simrad EM1000 multibeam echosounder mounted on the Canadian Coast Guard ship Frederick G. Creed. The multibeam system utilizes 60 electronically-aimed receive beams spaced at intervals of 2.5 degrees that insonify a strip of sea floor up to 7.5 times the water depth. The horizontal resolution of the beam on the sea floor is approximately 10 % of the water depth. Vertical resolution is approximately 1 % of the water depth. Data were collected along tracklines spaced 5-7 times the water depth apart at a speed of 10-14 knots. The Sandy Hook artificial reef area was surveyed in a Zamboni pattern (for efficient turns at high speed) with lines running north-south. The Zamboni pattern yields blocks of northward-run lines adjacent to blocks of southward-run lines. The frequency of the sonar was 95 kHz. Sound velocity profiles were obtained and input into the Simrad processing system to correct for refraction. Navigation was by means of differential GPS. Operation of the Simrad EM1000 was carried out by hydrographers of the Canadian Hydrographic Service. The data were collected on Woods Hole Coastal and Marine Science Center field activity 2000-015-FA (https://cmgds.marine.usgs.gov/fan_info.php?fa=2000-015-FA).
  2. How were the data generated, processed, and modified?
    Date: 2017 (process 1 of 5)
    A suite of processing software, called SwathEd, developed by the Ocean Mapping Group at the University of New Brunswick, Canada, was used to process and grid the multibeam data and to produce images. The metadata for the bathymetric grid (see larger work citation) describes the processing steps applied to the navigation and bathymetric soundings. The following processing steps produced the grayscale image of backscatter intensity for the Sandy Hook artificial reef data set:
    1. Create a blank 8 bit map file:
    Command line: make_blank mosaic_file
    This command commences a dialog to enable an 8 bit image and input the map boundaries and resolution (2 meters in this case). Then the "blank" file is copied to two files required by the mosaic program:
    Command line: cp mosaic_file.blank mosaic_file.mos Command line: cp mosaic_file.blank mosaic_file.ran
    2. Create backscatter files that can then be mosaicked from the backscatter time series:
    Command line: getBeamPattern filename (prefix only) Command line: makess -pixel 1.0 -beam_patt beampatt filename (prefix only) output.ss Command line: glfill output.ss output.ss_fill (fills in data dropouts).
    3. Mosaic all the backscatter files created in the last step (for each output.ss_fill).
    Command line: mos2 -autoseam -maxazi 10 -maxdist 10 mosaic_file output.ss_fill Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 x2274 (voice)
    bdanforth@usgs.gov
    Date: 2017 (process 2 of 5)
    Use a two-point linear contrast stretch (0-254; 255 no data) to enhance the backscatter image:
    Command line: stretchacres -low 180 -high 220 -in mosaic_file -out mosaic_file.stretch
    Create a TIFF from the backscatter mosaic file using the netpbm utilities (http://netpbm.sourceforge.net/):
    Command line: rawtopgm -headerskip 1024 image_width image_height mosaic_file.stretch | pnmtotiff -none - > mosaic_grayscale.tif Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 x2274 (voice)
    bdanforth@usgs.gov
    Date: 2017 (process 3 of 5)
    Create a TIFF world file (tfw) for the mosaic TIFF image for import to ArcGIS. Copy bounding box and resolution from the jview program output to the .tfw file.
    Command line: jview mosaic_file.stretch Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 x2274 (voice)
    bdanforth@usgs.gov
    Date: 2017 (process 4 of 5)
    Create GeoTIFF from TIFF image and world file using the Define Projection Tool in Data Management Tools, Projections and Transformations in ArcToolbox 9.3. Projection is custom Mercator, central meridian of -75.0 degrees, latitude of true scale 40.0 degrees north, false easting 0.0, false northing 0.0; Geographic Coordinate System WGS 1984. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Bradford Butman
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x 2212 (voice)
    bbutman@usgs.gov
    Date: 13-Apr-2026 (process 5 of 5)
    Added keywords section with USGS persistent identifier as theme keyword (20200807). Removed the web services distribution formats in preparation for ScienceBase moving platforms and those services will no longer be available (20260413). 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
  3. What similar or related data should the user be aware of?
    New Jersey Division of Fish and Wildlife, Unknown, Sandy Hook Reef.

    Online Links:

    New Jersey Department of Environmental Protection, Division of Fish and Wildlife, 2017, Artificial Reef Program.

    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?
    These data were navigated with a Differential Global Positioning System (DGPS); they are accurate to +/- 3 meters, horizontally.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    All data from the multibeam survey of the Sandy Hook artificial reef are included in the mosaic. There are a few gaps in the image due to incomplete coverage by the multibeam system.
  5. How consistent are the relationships among the observations, including topology?
    All data were processed in the same manner. Some features in the multibeam backscatter intensity data are artifacts of data collection and environmental conditions. They include unnatural-looking features and patterns oriented parallel or perpendicular to survey tracklines. The orientation of the tracklines is sometimes identified by the faint parallel stripes in the image.

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 None
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Federal Center
    Denver, CO

    1-888-275-8747 (voice)
  2. What's the catalog number I need to order this data set? shreef_backi2m.zip: contains the image of backscatter intensity (shreef_backi2m.tif), world file for the image (shreef_backi2m.tfw), browse graphic (shreef_backi2m_browsegraphic.jpg), and associated FGDC-compliant metadata (CSDGM format).
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the U.S. Geological Survey, 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?
    The GeoTIFF image of backscatter intensity and associated metadata from the Sandy Hook artificial reef survey are available in a zip file (shreef_backi2m.zip). To utilize these data, the user must have software capable of uncompressing the zip file and GIS software capable of displaying a GeoTIFF image.

Who wrote the metadata?

Dates:
Last modified: 13-Apr-2026
Metadata author:
U.S. Geological Survey
Attn: Bradford Butman
Woods Hole Coastal and Marine Science Center
Woods Hole, MA
USA

508-548-8700 x2212 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240319)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_F74F1PNH/shreef_backi2m.tif_meta.faq.html>
Generated by mp version 2.9.51 on Tue May 12 16:23:29 2026