Swath bathymetry 13-m-cell-size grid of quadrangle 6 on Stellwagen Bank offshore of Boston, Massachusetts collected by the U.S. Geological Survey aboard the Frederick G. Creed from 1994-1996 (custom Mercator projection, NAD 83, Esri binary grid format)

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Frequently anticipated questions:


What does this data set describe?

Title:
Swath bathymetry 13-m-cell-size grid of quadrangle 6 on Stellwagen Bank offshore of Boston, Massachusetts collected by the U.S. Geological Survey aboard the Frederick G. Creed from 1994-1996 (custom Mercator projection, NAD 83, Esri binary grid format)
Abstract:
The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration's National Marine Sanctuary Program, has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary region since 1993. The area is approximately 3,700 square kilometers (km2) and is subdivided into 18 quadrangles. Seven maps, at a scale of 1:25,000, of quadrangle 6 (211 km2) depict seabed topography, backscatter, ruggedness, geology, substrate mobility, mud content, and areas dominated by fine-grained or coarse-grained sand. Interpretations of bathymetric and seabed backscatter imagery, photographs, video, and grain-size analyses were used to create the geology-based maps. In all, data from 420 stations were analyzed, including sediment samples from 325 locations. The seabed geology map shows the distribution of 10 substrate types ranging from boulder ridges to immobile, muddy sand to mobile, rippled sand. Substrate types are defined on the basis of sediment grain-size composition, surficial morphology, sediment layering, and the mobility or immobility of substrate surfaces. This map series is intended to portray the major geological elements (substrates, features, processes) of environments within quadrangle 6. Additionally, these maps will be the basis for the study of the ecological requirements of invertebrate and vertebrate species that utilize these substrates and guide seabed management in the region.
  1. How might this data set be cited?
    Valentine, Page C., 2015, Swath bathymetry 13-m-cell-size grid of quadrangle 6 on Stellwagen Bank offshore of Boston, Massachusetts collected by the U.S. Geological Survey aboard the Frederick G. Creed from 1994-1996 (custom Mercator projection, NAD 83, Esri binary grid format): Scientific Investigations Map 3341, 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.

    Valentine, Page C., and Gallea, Leslie B., 2015, Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in quadrangle 6 of the Stellwagen Bank National Marine Sanctuary region offshore of Boston, Massachusetts: Scientific Investigations Map 3341, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.222299
    East_Bounding_Coordinate: -70.033471
    North_Bounding_Coordinate: 42.322320
    South_Bounding_Coordinate: 42.202807
  3. What does it look like?
    http://pubs.usgs.gov/sim/3341/data/bathy/q6_bathy.jpg (JPEG)
    Thumbnail images showing the 13-meter bathymetry grid in quadrangle 6 on Stellwagen Bank National Marine Sanctuary.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1994
    Ending_Date: 1996
    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 1031 x 1210 x 1, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      The map projection used is Mercator.
      Projection parameters:
      Standard_Parallel: 41.650000
      Longitude_of_Central_Meridian: -70.316667
      False_Easting: 0.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 13.000000
      Ordinates (y-coordinates) are specified to the nearest 13.000000
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean lower low water
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Implicit coordinate
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    These values represent depth. The more negative the value, the deeper the water.
    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)
    • Page C. Valentine
  2. Who also contributed to the data set?
    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 source of this information.
  3. To whom should users address questions about the data?
    Page C. Valentine
    U.S. Geological Survey
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov

Why was the data set created?

The purpose of this dataset is to release the 13-meter by 13-meter cell-size bathymetry grid that was used as the basis for analysis and used to generate several subsequent datasets, some of which are released in other publications (1-m contours, terrain ruggedness) in quadrangle 6 of the Stellwagen Bank National Marine Sanctuary region.

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: 1996 (process 1 of 5)
    Initial data collection and processing is described in Valentine and others 1999, Valentine 2005, and Butman and others, 2007. A summary of that information is presented here. Surveying was conducted aboard the Canadian Hydrographic Service vessel Frederick G. Creed using a hull mounted multibeam echo sounder. These data were collected using a Simrad Subsea EM1000 operating at 95 kHz. SwathEd software (version unknown) developed by the Ocean Mapping Group, University of New Brunswick, was used to process the bathymetric and navigation data. The processing included editing the data to remove spurious points as well as incorporate tidal corrections. Processing took place over a span of time, 1994 to 1996.
    Date: 2001 (process 2 of 5)
    The remaining process steps are a function of incorporating information from the previous publications (noted in cross-references), along with processing notes maintained during data processing. The final SwathEd-produced file (based on a 10-meter-grid-cell size) was converted to an ASCII file using the University of New Brunswick script r4toASCII. The format of the ASCII file is latitude, longitude, and depth. The ASCII file was converted to an ArcInfo ungenerate format using a Perl script. The resulting format is ID, longitude, latitude, and negative depth. Each point has a unique ID value. Using ArcInfo 7.03, the ungenerate format was converted to a coverage format using the 'convert to arc' from 'generate tool' available in ArcTools. The 'build' command with the point option was then used to convert the data to a point coverage. This procedure generates the point locations stored in the ungenerate file, but does not incorporate the depth values. In order to include depth, the ungenerate file - which has location as well as depth - was converted to an ArcInfo table, using 'Tables' in ArcInfo. The structure of the ArcInfo table was defined to include the ID, longitude, latitude, and depth in the appropriate format and size. Longitude and latitude were defined as floating point numbers with six decimal places, while depth was defined as a floating point number with two decimal places. To add the depth value to the point coverage, ArcInfo 'Tables' was used to join the point attribute table (pat) of the coverage to the newly-generated data table based on the ID value. In order to join the tables, the data table ID field had to be renamed to match the automatically assigned coverage ID field. The projection of the point coverage was defined in ArcInfo with the PROJECTDEFINE command and the following parameters: Projection Geographic; Datum NAD83; Units DD; Spheroid GRS80. This process was performed by Jessica Baker in 1997. Then the coverage was projected to the custom Mercator projection using the ArcInfo PROJECT command with the following options: Projection Mercator; Datum NAD83, Spheroid GRS1980; Units Meters; Longitude of Central Meridian -70degrees 19minutes; Latitude of true scale 41degrees 39minutes; False Easting 0; False northing 0. This process was performed by Jessica Baker in 1997. The final step was to convert the points to a grid. This was accomplished using the ArcInfo 'pointgrid' command. The depth attribute was gridded at a cell size of 13 meters, and the background value was set to nodata. This final processing step was performed in 1997, and then again by Tammie Middleton in 2001 and is the grid presented here. The 13-meter cell-size was chosen because it appeared to be the best cell size to avoid striping in the data when processing with the SwathEd software.
    Date: 2012 (process 3 of 5)
    Metadata for the original 13-m-cell-size grid was written to enable releasing the data as part of a USGS publication. The original work on Stellwagen Bank was based on 18 individual quadrangles, and the 13-m grid was the foundation of much of the subsequent work that appears on maps of the Stellwagen Bank area. The information used to generate metadata was based on previous publications, the extensive data processing log prepared by Tanya Unger and Jessica Baker, as well as the individual log files generated during ArcInfo data processing. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 4 of 5)
    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: 08-Sep-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?
    Valentine, Page C., Unger, Tanya S., Baker, Jessica L., and Polloni, Christopher F., 1999, Sun-illuminated sea floor topographic maps and perspective-view imagery of quadrangles 1-18, Stellwagen Bank National Marine Sanctuary off Boston, Massachusetts: Open-File Report 99-363, U.S. Geological Survey, Reston, VA.

    Online Links:

    Page C. Valentine, editor, 2005, Sea floor image maps showing topography, sun-illuminated topography, backscatter intensity, ruggedness, slope, and the distribution of boulder ridges and bedrock outcrops in the Stellwagen Bank National Marine Sanctuary region off Boston, Massachusetts: Scientific Investigations Map 2840, U.S. Geological Survey, Reston, VA.

    Online Links:

    Butman, Bradford, Valentine, Page C., Middleton, Tammie J., and Danforth, William W., 2007, A GIS library of multibeam data for Massachusetts Bay and the Stellwagen Bank National Marine Sanctuary, offshore of Boston, Massachusetts: Data Series 99, 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?
    These data were navigated with a differential global positioning system (DGPS) with an assumed accuracy of +/- 10 meters.
  3. How accurate are the heights or depths?
    These data have been corrected for vessel motion (roll, pitch, heave, yaw) and tidal offsets, and referenced to mean lower low water. The manufacturer reported vertical resolution of the Simrad EM-1000 multibeam echo sounder is 1% of water depth, which is better than 2 m given the depths within the study area (~30 to 184 meters). Data were corrected for tidal elevation using the NOAA Boston tide gauge.
  4. Where are the gaps in the data? What is missing?
    These data represent all the bathymetry data available in quadrangle 6 of the Stellwagen Bank study area. These represent a more "raw" version of the data that has not undergone extensive smoothing. There are some small gaps of no data within the grid.
  5. How consistent are the relationships among the observations, including topology?
    The original bathymetry data were acquired and processed in a consistent manner. Although several individuals were responsible for processing the data, each individual followed the established processing techniques.

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: Not to be used for navigation.
  1. Who distributes the data set? (Distributor 1 of 1)
    Page C. Valentine
    U.S. Geological Survey
    Research Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2239 (voice)
    (508) 457-2310 (FAX)
    pvalentine@usgs.gov
  2. What's the catalog number I need to order this data set? SIM3341_13mbathy.zip - This file contains the Esri binary grid of the bathymetry data (q6_13mbathy), along with FGDC compliant metadata and the browse graphic q6_bathy.jpg. The binary grid is comprised of two folders - info and q6_13mbathy, each having numerous files. These combine to make the Esri binary grid 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?
    These data are available as an ArcInfo 32-bit floating point binary grid in Esri format. The user must have a program capable of reading the Esri grid data format. The user must have software capable of uncompressing archived zip files, such as WinZip or Pkware. The directory structure as it appears in the WinZip file must be maintained or else the binary grid is unusable.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@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/sim/sim3341/q6_13mbathymeta.faq.html>
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