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CAPENORTH_GEO4M_XYZ.TXT: ASCII formatted file of the 4-m bathymetry from the northern half of USGS survey 98015 of the Sea Floor off Eastern Cape Cod (Geographic)

Metadata also available as: OUTLINE | TEXT

Frequently-anticipated questions:

What does this data set describe?

Title:
CAPENORTH_GEO4M_XYZ.TXT: ASCII formatted file of the 4-m bathymetry from the northern half of USGS survey 98015 of the Sea Floor off Eastern Cape Cod (Geographic)
Abstract:
This data set includes bathymetry of the sea floor offshore of eastern Cape Cod, Massachusetts. The data were collected with a multibeam sea floor mapping system during USGS survey 98015, conducted November 9 - 25, 1998. The surveys were conducted using a Simrad EM 1000 multibeam echosounder mounted aboard the Canadian Coast Guard vessel Frederick G. Creed. This 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 (swath width of 100 to 200 m within the survey area). The horizontal resolution of the beam on the sea floor is approximately 10% of the water depth. Vertical resolution is approximately 1 percent of the water depth.
  1. How should this data set be cited?

    U.S. Geological Survey, 2006, CAPENORTH_GEO4M_XYZ.TXT: ASCII formatted file of the 4-m bathymetry from the northern half of USGS survey 98015 of the Sea Floor off Eastern Cape Cod (Geographic): Open-File Report 2005-1048, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Poppe, L.J., Paskevich, V.F., Butman, B., Ackerman, S.D., Danforth, W.W., Foster, D.S., and Blackwood, D.S., 2006, Geological Interpretation of Bathymetric and Backscatter Imagery of the Sea Floor off Eastern Cape Cod, Massachusetts: Open-File Report 2005-1048, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -70.307809
    East_Bounding_Coordinate: -69.828308
    North_Bounding_Coordinate: 42.116649
    South_Bounding_Coordinate: 41.966641

  3. What does it look like?

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

    Beginning_Date: 09-Nov-1998
    Ending_Date: 25-Nov-1998
    Currentness_Reference: ground condition

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

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Point data set.

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

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      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:
      Altitude_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean lower low water
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    Three comma separated values (CSV) per record. Value one is the latitude coordinate in decimal degrees of the ship coordinate; value 2 is the longitude coordinate in decimal degrees of the ship's coordinate; value three is the acquired depth value. The depth value is recorded in meter as a negative value

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?

    U.S. Geological Survey
    c/o Lawrence Poppe
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543-1598
    USA

    (508) 548-8700 x2314 (voice)
    (508) 457-2310 (FAX)
    lpoppe@usgs.gov

Why was the data set created?

To release the ASCII file containing the 4-m bathymetry generated from USGS survey 98015 off eastern Cape Cod.

How was the data set created?

  1. From what previous works were the data drawn?

    98015_multibeam_data (source 1 of 1)
    .

    Type_of_Source_Media: DVD-ROM
    Source_Contribution:
    The original multibeam bathymetric data acquired with a Simrad EM 1000 echosounder during USGS cruise 98015 aboard the Canadian Coast Guard vessel Frederick G. Creed

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

    Date: Unknown (process 1 of 2)
    (1) Data and acquisition processing at sea: After the echo sounder data were logged onto the hard disk of the Sun workstation, a suite of processing software developed by the Ocean Mapping Group (www.omg.unb.ca/~jhc/SwathEd.html) was used to correct for artifacts and errors that may have been introduced during data collection. This software also enhanced the corrected data by resolving beam pattern and aspect ratio distortions and by imposing a linear contrast stretch before it generated bathymetric and sidescan sonar image mosaicks in a Mercator projection. All data processing described here is initiated using Silicon Graphics workstations as soon as each acquisition file is closed by the Simrad Mermaid workstation (usually at the end of each survey line). Additional processing was done in the lab to correct for fluctuations in sea level during the survey and for artifacts in the data files that were not corrected in the field (see below).

    (2) The processing and editing steps on board the ship were:

    (A.) Demultiplex, or unravel, the acquired Simrad data files using RT to generate separate files containing navigation, depth soundings, sidescan sonar backscatter values, and sound velocity information.

    (B.) Automatically reject bad data (autoRejectSoundings). For the multibeam soundings, reject data outside expected depth ranges (operator's decision based on nautical chart data); for navigation data, reject fixes with poor GPS statistics.

    (C.) Edit the navigation data on-screen using jview to remove undesirable points, including turns at the ends of survey lines.

    (D.) Edit the multibeam soundings on-screen using swathed to remove individual anomalous soundings.

    (E). Merge tidal information and the corrected navigation back (mergetide and mergenav) into the data files. Tidal information was obtained from predicted tides using the Xtide program <http://www.flaterco.com/xtide/xtide.html>), which generated predicted tides based on the harmonic coefficients for Chatham provided by the Xtide program.

    (F.) Map the bathymetric soundings from each processed data file onto a Mercator grid using weigh_grid (a SwathEd utility) with node spacings and scale selected by the operator. The grid file (capenorth.r4) was a floating point binary file.

    Person who carried out this activity:

    William Danforth
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543-1598
    USA

    (508) 548-8700 x2274 (voice)
    (508) 457-2310 (FAX)
    bdanforth@usgs.gov

    Data sources used in this process:
    • 98015_multibeam_data

    Data sources produced in this process:

    • capenorth.r4

    (process 2 of 2)
    The SwathEd-created grid was converted into an ASCII xyz (decimal degrees and depths in negative meters) text file using a SwathEd utility (r4toASCII).

    Data sources used in this process:

    • capenorth.r4

    Data sources produced in this process:

    • capenorth_geo4m_xyz.txt

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

    Poppe, L.J., Foster, D.S., and Danforth, W.W., 2006, Character and distribution of exposed glaciodeltaic deposits off outer Cape Cod, Massachusetts, and their effects on hydrogeology and benthic habitats: Geo-Marine Letters v. 26, Springer, Germany.

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

  3. How accurate are the heights or depths?

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

    All collected data were processed and used to produce this dataset.

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

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:
Data are not to be used for navigation purposes.

Public domain data are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.

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

    U.S. Geological Survey
    c/o Larry Poppe
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543-1598
    USA

    (508) 548-8700 x2314 (voice)
    (508) 457-2310 (FAX)
    lpoppe@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?

    Although this data set has been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. 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 user must have a program capable of reading and processing ASCII formated XYZ data files.

Who wrote the metadata?

Dates:
Last modified: 12-Feb-2006
Metadata author:
Larry Poppe
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA 02543-1598
USA

(508) 548-8700 x2314 (voice)
(508) 457-2310 (FAX)
lpoppe@usgs.gov

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

Generated by mp version 2.8.6 on Thu Mar 23 10:07:37 2006