GeoTIFF image of the backscatter intensity of the sea floor of the Hudson Canyon region (100-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 Hudson Canyon region (100-m resolution, Mercator, WGS 84)
Abstract:
The Hudson Canyon begins on the outer continental shelf off the east coast of the United States at about 100-meters (m) water depth and extends offshore southeastward across the continental slope and rise. A multibeam survey was carried out in 2002 to map the bathymetry and backscatter intensity of the sea floor of the Hudson Canyon and adjacent slope and rise. The survey covered an area approximately 205 kilometers (km) in the offshore direction, extending from about 500 m to about 4,000 m water depth, and about 110 km in the alongshore direction, centered on the Hudson Canyon. The sea floor was mapped using a SeaBeam Instruments 2112 multibeam echosounder aboard the National Oceanic and Atmospheric Administration (NOAA) ship Ronald H. Brown. Maps derived from the multibeam observations show sea-floor bathymetry and backscatter intensity (a measure of sea floor texture and roughness), geomorphic provinces, and sea-floor environments (Butman and others, 2006). The sea floor was mapped by the U.S. Geological Survey in cooperation with Rutgers University and with support from NOAA.
Supplemental_Information:
Maps and interpretations of the multibeam echosounder data from the 2002 multibeam survey of the sea floor of the Hudson Canyon region are published in Butman and others (2006) (see cross reference). This publication includes the previously unpublished digital multibeam data and interpretations with FGDC-compliant metadata (CSDGM format). The data were collected on Woods Hole Coastal and Marine Science Center field activity 2002-050-FA (https://cmgds.marine.usgs.gov/fan_info.php?fan=2002-050-FA). Other datasets from the 2002 survey may be found in Butman and others (2017) (see larger work citation). Andrews and others (2013) (see cross reference) present a bathymetric terrain model for the Atlantic margin which includes the Hudson Canyon region.
  1. How might this data set be cited?
    U.S. Geological Survey, 2017, GeoTIFF image of the backscatter intensity of the sea floor of the Hudson Canyon region (100-m resolution, Mercator, WGS 84): data release DOI:10.5066/F77H1GSF, 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., Twichell, David C., and Rona, Peter A., 2017, Bathymetry, backscatter intensity, and geomorphology of the sea floor of the Hudson Canyon and adjacent slope and rise: data release DOI:10.5066/F77H1GSF, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Butman, Bradford, Danforth, W.W., Twichell, D.C., and Rona, P.A., 2017, Bathymetry, backscatter intensity, and geomorphology of the sea floor of the Hudson Canyon and adjacent slope and rise: U.S. Geological Survey data release, https://doi.org/10.5066/F77H1GSF.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -72.583333
    East_Bounding_Coordinate: -70.050364
    North_Bounding_Coordinate: 39.866667
    South_Bounding_Coordinate: 37.583745
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/58fa5e29e4b0b7ea54525621?name=hc_rb_backi_browsegraphic.jpg (JPEG)
    Browse graphic of the backscatter intensity of the sea floor of the Hudson Canyon region.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 30-Aug-2002
    Ending_Date: 15-Sep-2002
    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 2489 x 2163 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 100.000000
      Ordinates (y-coordinates) are specified to the nearest 100.000000
      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 tracklines. 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
  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
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA
    USA

    508-548-8700 x2212 (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)
    NOAA, Bolmer, S. Thompson, Robb, James M., and Rona, Peter A., Unpublished Material, raw SeaBeam 2112 multibeam data.

    Type_of_Source_Media: disc
    Source_Contribution:
    A SeaBeam Instruments 2112 multibeam Echo Sounder (12 kHz) was used to acquire the bathymetric data on the NOAA ship Ronald H. Brown. This system utilized up to 151 electronically aimed beams spaced at intervals of 2 degrees that insonify a swath of sea floor up to 3 times the water depth. Over the continental rise, in water depths greater than about 2,000 m, a 5-km track separation was employed, which provided almost 100% overlap of the insonified area from swath to swath. Time considerations compelled less than ideal coverage of the continental slope area, where a track-line separation of about 1.7 km was used, that provided nearly no data overlap between swaths. The survey was conducted at approximately 10 knots (18.5 km/hr). The horizontal resolution of the beam on the sea floor ranged from about 20-65 m in the across-track direction and about 10 m in the along-track direction at 500 m water depth, and from about 100-400 m across-track and 40 m along-track at 3,000 m water depth. Navigation was by GPS. The data were collected on Woods Hole Coastal and Marine Science Center field activity 2002-050-FA (https://cmgds.marine.usgs.gov/fan_info.php?fan=2002-050-FA).
  2. How were the data generated, processed, and modified?
    Date: 2009 (process 1 of 5)
    A suite of processing software (called SwathEd) (Clarke, 1998; see cross reference) developed by the Ocean Mapping Group at the University of New Brunswick (UNB), Canada, was used to process, edit, grid, display, and archive the multibeam data. 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 2002 Hudson Canyon SeaBeam datasets:
    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 (100 meters in this case). The program also prompts for the projection type and parameters to be used creating the binary map file (Mercator, central longitude of -75 degrees, latitude of true scale 40 degrees north). 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 be then mosaicked from the SeaBeam sidescan data:
    Command line: removeAngular -use_calib filename.mb41.merged Command line: makess filename.mb41.merged filename.mb41.ss Command line: glhist filename.mb41.ss filename.mb41.ss_hist
    3. Mosaic all the backscatter files created in the last step (for each filename.ss_hist).
    Command line: mos2 -autoseam -auto_dg -custom_weight BEAM_weights -maxdist 50 mosaic_file filename.mb41.ss_hist
    Note: Errors in the UNB gridding software were identified in 2003 and 2007. These data were processed with corrected software. 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: 2016 (process 2 of 5)
    Use a two point linear contrast stretch 0-254; 255 is no data) to enhance the shaded-relief image:
    Command line: stretchacres -low 110 -high 140 -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: 2015 (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: 2016 (process 4 of 5)
    Create GeoTIFF image 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: 07-Aug-2020 (process 5 of 5)
    Added keywords section with USGS persistent identifier as theme keyword. 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?
    Butman, Bradford, Twichell, D.C., Rona, P.A., Tucholke, B.E., Middleton, T.J., and Robb, J.R., 2006, Sea floor topography and backscatter intensity of the Hudson Canyon region offshore of New York and New Jersey: Open-File Report 2004-1441, U.S. Geological Survey, Reston, VA.

    Online Links:

    Butman, Bradford, Middleton, T.J., Thieler, E.R., and Schwab, W.C., 2003, Topography, shaded relief and backscatter intensity of the Hudson Shelf Valley, offshore of New York: Open-File Report 03-372, U.S. Geological Survey, Reston, VA.

    Online Links:

    Andrews, B.D., Chaytor, J.D., ten Brink, U.S., Brothers, D.S., and Gardner, J.V., 2013, Bathymetric terrain model of the Atlantic margin for marine geological investigations: Open-File Report 2012-1266, U.S. Geological Survey, Reston, VA.

    Online Links:

    Clarke, J.H., 1998, SwathEd: Ocean Mapping Group, University of New Brunswick, New Brunswick, Canada.

    Online Links:

    Butman, Bradford, Danforth, W.W., Clarke, J.E.H., and Signell, R.P., 2017, Bathymetry and backscatter intensity of the sea floor of the Hudson Shelf Valley: data release DOI:10.5066/F7C53J1Z, U.S. Geological Survey, Reston, VA.

    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?
    Navigation was by differential GPS. Horizontal accuracy is approximately 10 m.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This image includes backscatter intensity data collected with a SeaBeam Instruments 2112 multibeam mapping system on Woods Hole Coastal and Marine Science Center field activity 2002-050-FA (https://cmgds.marine.usgs.gov/fan_info.php?fan=2002-050-FA). There are a few gaps in the image due to incomplete coverage by the multibeam system. Other datasets from the 2002 survey of the Hudson Canyon may be found in Butman and others (2017) (see larger work citation).
  5. How consistent are the relationships among the observations, including topology?
    All data were processed in the same manner. Some features in the multibeam data are artifacts of data collection and environmental conditions. They include small highs and lows and 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
    Denver Federal Center
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? hc_rb_backi.zip: contains hc_rb_backi.tif, hc_rb_backi.tfw, 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 USGS 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 is compressed into a zip file (hc_rb_backi.zip). To use these data, the user must have software capable of uncompressing the zip file and ArcGIS or another GIS application package capable of viewing the data

Who wrote the metadata?

Dates:
Last modified: 07-Aug-2020
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)
bbutman@usgs.gov
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_F77H1GSF/hc_rb_backi.tif_meta.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:57 2021