GeoTIFF image of the backscatter intensity of the sea floor of the Hudson Shelf Valley (12-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 Shelf Valley (12-m resolution, Mercator, WGS 84)
Abstract:
The Hudson Shelf Valley is the submerged seaward extension of the ancestral Hudson River drainage system and is the largest physiographic feature on the Middle Atlantic continental shelf. The valley begins offshore of New York and New Jersey at about 30-meter (m) water depth, runs southerly and then southeasterly across the Continental Shelf, and terminates on the outer shelf at about 85-m water depth landward of the head of the Hudson Canyon. Portions of the 150-kilometer-long valley were surveyed in 1996, 1998, and 2000 using a Simrad EM1000 multibeam echosounder mounted on the Canadian Coast Guard ship Frederick G. Creed. The purpose of the multibeam echosounder surveys was to map the bathymetry and backscatter intensity of the sea floor of the valley, providing a framework for geologic, oceanographic, and geochemical studies. The data from the three surveys are combined to produce grids of bathymetry and backscatter intensity at 12-m resolution that cover the entire valley and the head of the Hudson Canyon. The mapping was done by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers with support from the Canadian Hydrographic Service and the University of New Brunswick.
Supplemental_Information:
Butman and others (1998), Butman and others (2003), and Thieler and others (2007) (see cross references) present maps and interpretations of the multibeam data. In the image presented in Butman and others (2003), the value 255 included both no data and the maximum data value. In this image, the value 255 is no data. Other datasets from the survey of the Hudson Shelf Valley may be found in Butman and others (2017) (see larger work citation).
  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 Shelf Valley (12-m resolution, Mercator, WGS 84): data release DOI:10.5066/F7C53J1Z, 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 Hudson Shelf Valley: data release DOI:10.5066/F7C53J1Z, 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 Hudson Shelf Valley: U.S. Geological Survey data release, https://doi.org/10.5066/F7C53J1Z.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.901667
    East_Bounding_Coordinate: -71.999938
    North_Bounding_Coordinate: 40.433333
    South_Bounding_Coordinate: 39.333341
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/589a1ffee4b0efcedb71a59c?name=hsv_backi12m_browsegraphic.jpg (JPEG)
    Browse graphic of the backscatter intensity of the sea floor.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 23-Nov-1996
    Ending_Date: 04-May-2000
    Currentness_Reference:
    Ground condition. Surveys of different parts of the valley were carried out 19961123 to 19961201, 19981029 to 19981102, and 20000407 to 20000504.
  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 10161 x 13533 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 12.000000
      Ordinates (y-coordinates) are specified to the nearest 12.000000
      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, 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. Some striping is also due to critical angle effects, where the intensity of return varies as a function of the angle of incidence of the incoming sound on the seafloor. 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
    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. The image merges backscatter intensity data obtained in 1996, 1998, and 2000.

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 starboard pontoon of 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 valley was surveyed with lines running approximately parallel to the valley axis; in some areas the lines were run in a Zamboni pattern for efficiency. The piecemeal survey pattern was a result of the limited endurance of the Creed, about 2 days, and weather. The frequency of the sonar is 95 kHz. Sound velocity profiles, used to correct for refraction, were obtained when arriving at the start of each portion of the survey and then twice each day. 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 activities 1996-043-FA (https://cmgds.marine.usgs.gov/fan_info.php?fa=1996-043-FA), 1998-015-FA (https://cmgds.marine.usgs.gov/fan_info.php?fa=1998-015-FA), and 2000-015-FA (https://cmgds.marine.usgs.gov/fan_info.php?fa=1998-015-FA).
  2. How were the data generated, processed, and modified?
    Date: 2009 (process 1 of 6)
    A suite of processing software (called SwathEd) (Clarke, 1998; see cross reference), developed by the Ocean Mapping Group at the University of New Brunswick, Canada, was used to process the multibeam backscatter intensity data and produce images. The following processing steps produced the combined grayscale image of backscatter intensity for the 1996, 1998, and 2000 Hudson Shelf Valley 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 (12 meters in this case). The program also prompts for the projection type and parameters to be used creating the binary map file (custom 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 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
    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 6)
    Use a two point linear contrast stretch (0-254; 255 is no data) to enhance the shaded-relief image.
    (Note the value 255 in images presented in Butman and others (2003) included both no data and maximum data value. In this image, the value 255 is no data.)
    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: 2007 (process 3 of 6)
    Create a TIFF world file (tfw) for the mosaic TIFF image for import to ArcGIS. Copy bounding box and resolution information from the jview program output to the tfw file using UNIX text editor vi.
    Command line: jview mosaic_file.stretch
    This file was created in 2007 for use with intermediate versions of the TIFF image and is unchanged for all versions. 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 6)
    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: 20-Jul-2018 (process 5 of 6)
    USGS Thesaurus keywords added to the keyword section. 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
    Date: 10-Aug-2020 (process 6 of 6)
    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, 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:

    Thieler, E.R., Butman, Bradford, Schwab, W.C., Allison, M.A., Driscoll, N.W., Donnelly, J.P., and Uchupi, Elazar, 2007, A catastrophic meltwater flood event and the formation of the Hudson Shelf Valley: Palaeogeography, Palaeoclimatology, Palaeoecology 246 (2007), 120-136; DOI: 10.1016/j.palaeo.2006.10.030, Elsevier Ltd., Amsterdam.

    Online Links:

    Butman, Bradford, Danforth, W.W., Schwab, W.C., and ten Brink, M.B., 1998, Multibeam bathymetric and backscatter maps of the upper Hudson Shelf Valley and adjacent shelf, offshore of New York: Open-File Report 98-616, U.S. Geological Survey, Reston, VA.

    Online Links:

    Butman, Bradford, Danforth, W.W., Knowles, S.C., May, Brian, and Serrett, Laurie, 2002, Sea floor topography and backscatter intensity of the Historic Area Remediation Site (HARS), offshore of New York, based on multibeam surveys conducted in 1996, 1998, and 2000: Open-File Report 00-503, U.S. Geological Survey, Reston, VA.

    Online Links:

    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:

    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 Historic Area Remediation Site in 1996, 1998, and 2000: data release DOI:10.5066/F74B2ZGX, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication contains edition 2.0 of the bathymetry and derivative datasets that were originally released as part of Open-File Report 00-503. Edition 2.0 was created using revised processing software to correct a projection error in edition 1.0. The stretch for the images in edition 2.0 was also changed so that 255 is no data.

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) which is typically accurate to +/- 3 meters, horizontally. Repeated surveys of the Historic Area Remediation Site (HARS) (Butman and others, 2017), made on the same cruises and using the same instrumentation as the surveys of the Hudson Shelf Valley, were used to qualitatively assess the horizontal accuracy of the 1996, 1998, and 2000 surveys. The difference in location of sea floor features in the HARS identified in the 1996 and 1998 surveys were typically 5 m or less, as expected when navigating with DGPS. The difference in location of same features in the 1998 and 2000 survey were typically 10-20 m and in the along-track direction of the survey. This analysis suggests that the data collected in 1996 and 1998 surveys of the Hudson Shelf Valley are accurate to +/- 3 m horizontally, and the data collected in the 2000 survey accurate to 10-20 m horizontally.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This image represents backscatter intensity data collected with a Simrad EM 1000 multibeam echosounder on Woods Hole Coastal and Marine Science Center field activities 1996-043-FA, 1998-015-FA, and 2000-015-FA that have been merged together. There are a few data gaps in the image due to incomplete coverage by the multibeam system. Other datasets from the survey of the Hudson Shelf Valley 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 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
    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? hsv_backi12m.zip: contains hsv_backi12m.tif, hsv_backi12m.tfw, hsv_backi12m_browsegraphic.jpg, and CSDGM FGDC-compliant metadata in XML, HTML, and TXT formats.
  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 the U.S. Army Corps of Engineers, 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 (hsv_backsc12m.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: 19-Mar-2024
Metadata author:
U.S. Geological Survey
Attn: Bradford Butman
384 Woods Hole Road
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_F7C53J1Z/hsv_backi12m.tif_meta.faq.html>
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