ASCII formatted file of the 4-m bathymetry from the southern half of USGS Survey 98015 of the Sea Floor off Eastern Cape Cod (CAPESOUTH_GEO4M_XYZ.TXT, Geographic, NAD83)

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Frequently anticipated questions:


What does this data set describe?

Title:
ASCII formatted file of the 4-m bathymetry from the southern half of USGS Survey 98015 of the Sea Floor off Eastern Cape Cod (CAPESOUTH_GEO4M_XYZ.TXT, Geographic, NAD83)
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 might this data set be cited?
    U.S. Geological Survey, 2006, ASCII formatted file of the 4-m bathymetry from the southern half of USGS Survey 98015 of the Sea Floor off Eastern Cape Cod (CAPESOUTH_GEO4M_XYZ.TXT, Geographic, NAD83): Open-File Report 2005-1048, 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.

    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, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -69.999976
    East_Bounding_Coordinate: -69.828314
    North_Bounding_Coordinate: 41.969982
    South_Bounding_Coordinate: 41.616648
  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?
    Geospatial_Data_Presentation_Form: tabular digital data
  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:
      Depth_System_Definition:
      Depth_Datum_Name: Mean lower low water
      Depth_Resolution: 9999
      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 mean lower low water recorded in meter as a negative value.
    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?
    Lawrence Poppe
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

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

Why was the data set created?

To release the ASCII data 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)
    USGS, unpublished material, Raw multibeam data.

    Other_Citation_Details:
    This file had a source contribution, but no source citation information. This information was populated based on information in the source contribution.
    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 4)
    (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 (capesouth.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
    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:
    • capesouth.r4
    Date: unknown (process 2 of 4)
    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:
    • capesouth.r4
    Data sources produced in this process:
    • capesouth_geo4m_xyz.txt
    Date: 09-Nov-2015 (process 3 of 4)
    Edits to the metadata were made to fix any errors that MP v 2.9.30 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. This file had a source contribution, but no source citation information. This information was populated based on information in the source contribution. No depth resolution was available, so that required value was set to 9999. The second process step had no process date, so that value was set to unknown. Other minor edits were probably performed (title, publisher, publication place, etc.). The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    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 4)
    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
  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?
    Information unavailable from original metadata.

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
    Attn: Larry Poppe
    Geologist
    384 Woods Hole Road
    Woods Hole, MA

    (508) 548-8700 (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: 20-Jul-2018
Metadata author:
Larry Poppe
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA
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)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/eastcoast/gome/capecod/capesouth_geo4m_xyz.txt.faq.html>
Generated by mp version 2.9.49 on Fri Sep 13 15:01:53 2019