H11044_1_5MDDEG_XYZ.TXT: Original Uninterpolated 1.5-m Bathymetry from NOAA Survey H11044 off Milford, Connecticut

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Frequently-anticipated questions:

What does this data set describe?

Title:
H11044_1_5MDDEG_XYZ.TXT: Original Uninterpolated 1.5-m Bathymetry from NOAA Survey H11044 off Milford, Connecticut
Abstract:
During 2001 the NOAA Ship RUDE completed charting survey H11044 that covered a roughly 293 km2 area of the sea floor in north-central Long Island Sound, off Milford Connecticut. Although 100 percent coverage was achieved with sidescan sonar for charting purposes, only reconnaissance (spaced line) bathymetry was acquired with shallow-water multibeam and single-beam systems. Therefore, further processing was conducted at the USGS's Woods Hole Science Center to provide bathymetric datasets with more continuous coverage. This project produced grids and GeoTIFF imagery of the combined and interpolated shallow-water multibeam and single-beam bathymetry generated from the northern part of this data set. Anthropogenic wastes, toxic chemicals, and changes in land-use patterns resulting from residential, commercial, and recreational development have stressed the environment of the Sound, causing degradation and potential loss of benthic habitats. Detailed maps of the sea floor are needed to help evaluate the extent of adverse impacts and to help manage resources wisely in the future. Therefore, in a continuing effort to better understand Long Island Sound, we have interpolated and gridded shallow-water multibeam and single-beam bathymetric data within specific areas of special interest.
  1. How should this data set be cited?

    National Oceanic and Atmospheric Administration, 2008, H11044_1_5MDDEG_XYZ.TXT: Original Uninterpolated 1.5-m Bathymetry from NOAA Survey H11044 off Milford, Connecticut: Open-File Report 2008-1146, 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., Ackerman, S.D., McMullen, K.Y., Schattgen, P.T., Schaer, J.D., and Doran, E.F., 2008, Interpolation of Reconnaissance Multibeam and Single-Beam Bathymetry Offshore of Milford, Connecticut: Open-File Report 2008-1146, 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: -73.131256
    East_Bounding_Coordinate: -72.936531
    North_Bounding_Coordinate: 41.2463314
    South_Bounding_Coordinate: 41.023193

  3. What does it look like?

    <http://pubs.usgs.gov/of/2008/1146/data/bathy/grids/geo/asciigrid/h11044_1_5mddeg_xyz.gif> (GIF)
    Thumbnail image showing the extent of soundings collected during NOAA survey H11044

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

    Beginning_Date: 07-May-2001
    Ending_Date: 13-Nov-2001
    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 0.000000001. Longitudes are given to the nearest 0.000000001. Latitude and longitude values are specified in Decimal degrees.

      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.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean lower low water
      Depth_Resolution: 0.001
      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 space separated values per record. Value one is latitude in decimal degrees of the ship coordinate; value 2 is the longitude in decimal degrees the ship's coordinate; value three is the acquired depth value. The depth value is recorded in meters (to three decimal places) as a positive 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 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

Why was the data set created?

To release the ASCII file containing the 1.5-m horizontally spaced bathymetry generated from NOAA survey H11044 in north-central Long Island Sound off Milford, Connecticut. This file contains the entire dataset, and not just the northern section covered by the other datasets released as part of this project.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    .

    Type_of_Source_Media: DVD-ROM
    Source_Contribution:
    The original processed shallow-water multibeam and single-beam bathymetric data.

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

    Date: Unknown (process 1 of 1)
    The multibeam data were acquired in XTF (extended Triton data format) and recorded digitally through an ISIS data acquisition system. A Reson SeaBat 9003 echosounder was used to acquire the shallow-water multibeam bathymetric data and an Odom Echotrac DF-3200 dual-frequency echosounder was used to acquire the single-beam bathymetry from the NOAA ship Rude. An Odom Echotrac DF-3200 dual-frequency echosounder hull-mounted on a 23' launch deployed from the NOAA ship Rude was used to acquire sounding data in the shallower areas. These data were processed using CARIS HIPS (Hydrographic Image Processing System) software for quality control, and to incorporate sound velocity and tidal corrections. Sound velocity corrections were derived using frequent SEACAT CTD (conductivity-temperature-depth) profiles. Typically, a CTD cast was conducted every four to six hours of multibeam acquisition. Tidal zone corrections were calculated from data acquired at tidal gauges at Bridgeport and NewHaven, Connecticut, and at Kings Point, New York. The vertical resolution of the shallow-water multibeam data is approximately 0.5% of the water depth. The data were gridded to 1.5-m resolution and exported in text (.txt) format. Vertical datum is mean lower low water; X and Y units are decimal degrees.

    Person who carried out this activity:

    National Oceanic and Atmospheric Administration
    c/o Tod Schattgen
    Commanding Officer
    439 West York Street
    Norfolk, VA 23510
    USA

    757-647-0187 (voice)
    Tod.Schattgen@noaa.gov

    Data sources produced in this process:
    • h11044_1_5mddeg_xyz.txt

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

    Poppe, L.J., Ackerman, S.D., Doran, E.F., Beaver, A.L., Crocker, J.M., and Schattgen, P.T., 2006, Interpolation of Reconnaissance Multibeam Bathymetry from North-Central Long Island Sound: Open-File Report 2005-1145, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    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

  3. How accurate are the heights or depths?

    The vertical resolution of the shallow-water multibeam data is approximately 0.5% of the water depth.

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

    All collected data from NOAA survey H11044 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 National Oceanic and Atmospheric Administration (NOAA) as the originator 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 (File size: Text version 2.74Gb, WinZipped version 7.86 Mb)

  3. What legal disclaimers am I supposed to read?

    Neither the U.S. Government, the Department of the Interior, the USGS, NOAA, Connecticut Department of Environmental Protection, 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. 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 formatted XYZ data files.

Who wrote the metadata?

Dates:
Last modified: 30-Sep-2008
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 Tue Sep 30 11:21:33 2008