H11252_2MUTM18_XYZ.TXT: 2-m ASCII Bathymetric Grid from National Oceanic and Atmospheric Administration (NOAA) Survey H11252 of the Sea Floor in Eastern Long Island Sound (UTM Zone18)

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Frequently-anticipated questions:


What does this data set describe?

Title:
H11252_2MUTM18_XYZ.TXT: 2-m ASCII Bathymetric Grid from National Oceanic and Atmospheric Administration (NOAA) Survey H11252 of the Sea Floor in Eastern Long Island Sound (UTM Zone18)
Abstract:
The U.S. Geological Survey, in cooperation with the National Oceanic and Atmospheric Administration and the Connecticut Department of Environmental Protection, has produced detailed geologic maps of the sea floor in Long Island Sound, a major East Coast estuary surrounded by the most densely populated region of the United States. These studies have built upon cooperative research with the State of Connecticut that was initiated in 1982. The current phase of this research program is directed toward studies of sea-floor sediment distribution, processes that control sediment distribution, nearshore environmental concerns, and the relation of benthic community structures to the sea-floor geology.

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 (Koppelman and others, 1976; Long Island Sound Study, 1994). 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 constructed and interpreted multibeam bathymetric data within specific areas of special interest. This bathymetric data layer presented herein covers a roughly 64 km square area of the sea floor in the area just west of Six Mile Reef, eastern Long Island Sound. The original multibeam bathymetric data were collected during 2004 as part of charting applications aboard the NOAA Survey Vessel Thomas Jefferson. A Simrad EM1002 multibeam system mounted on the hull of this vessel was used to acquire data along survey lines from the deeper water (>20 m) parts of the study area. Two 29-foot launches with hull-mounted Reson systems were deployed from the ship and were used to acquire data along survey lines from the shallower areas.

Detailed bathymetric data and their interpretations serve many purposes, including: (1) defining the geological variability of the sea floor, which is one of the primary controls of benthic habitat diversity; (2) improving our understanding of the processes that control the distribution and transport of bottom sediments and the distribution of benthic habitats and associated infaunal community structures; and (3) providing a detailed framework for future research, monitoring, and management activities. The bathymetric data models also serve as base maps for subsequent sedimentological, geochemical, and biological observations, because precise information on environmental setting is important for selection of sampling sites and for accurate interpretation of point measurements.

  1. How should this data set be cited?

    National Oceanic and Atmospheric Administration, 2007, H11252_2MUTM18_XYZ.TXT: 2-m ASCII Bathymetric Grid from National Oceanic and Atmospheric Administration (NOAA) Survey H11252 of the Sea Floor in Eastern Long Island Sound (UTM Zone18): Open-File Report 2007-1191, 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., Denny, J.F., Williams, S.J., Moser, M.S., Forfinski, N.A., Stewart, H.F., and Doran, E.F., 2007, The Geology of Six Mile Reef, Eastern Long Island Sound: Open-File Report 2007-1191, 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: -72.650332
    East_Bounding_Coordinate: -72.529370
    North_Bounding_Coordinate: 41.217184
    South_Bounding_Coordinate: 41.149146

  3. What does it look like?

    <http://pubs.usgs.gov/of/2007/1191/data/h11252/bathy/grids/utm/asciigrid/h11252_2mutm18_xyz.gif> (GIF)
    Thumbnail image showing the extent of soundings collected during NOAA survey H11252

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

    Calendar_Date: 2004
    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?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: .999600
      Longitude_of_Central_Meridian: -75.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000

      Abscissae (x-coordinates) are specified to the nearest 2.000359
      Ordinates (y-coordinates) are specified to the nearest 2.000000
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.

      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 space separated values per record. Value one is the eastings coordinate in meters of the ship coordinate; value 2 is the northings coordinate in meters the ship's coordinate; value three is the acquired depth value. The depth value is recorded in meters 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 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 an ASCII XYZ (Easting, Northing, and Depth) file containing the 2-m bathymetry generated from NOAA survey H11252 in Long Island Sound.


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 multibeam bathymetric data acquired with Simrad EM1002, Reson 8101, and 8125 echosounder systems during NOAA cruise H11252 aboard the NOAA ship Thomas Jefferson. A Simrad EM1002 multibeam system mounted on the hull of this vessel was used to acquire data along survey lines from the deeper water (>20 m) parts of the study area. Two 29-foot launches with hull-mounted Reson systems were deployed from the ship and were used to acquire data along survey lines from the shallower areas.

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

    Date: Unknown (process 1 of 2)
    The multibeam data were acquired in XTF (extended Triton data format), recorded digitally through an ISIS data acquisition system, and processed using CARIS HIPS (Hydrographic Image Processing System) software for quality control, to incorporate sound velocity and tidal corrections, and to produce base surfaces averaging 2-m resolution over the study area. The data were exported in text (.txt) format in UTM Zone 18.

    Person who carried out this activity:

    Marc Moser
    National Oceanic and Atmospheric Administration
    Field Operations Officer
    439 West York Street
    Norfolk, VA 23510
    USA

    (757) 441-6746 (voice)
    marc.s.moser@noaa.gov

    Data sources used in this process:
    • raw bathymetric data

    Data sources produced in this process:

    • h11252_2mutm18.xyz.txt

    (process 2 of 2)
    Metadata imported.

    Data sources used in this process:

    • D:\quickshole\ofr2006-1357\data\bathy\grids\asciigrid\h11076_1mutm19_xyz.txt.xml

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

    Poppe, L.J., Williams, S.J., Moser, M.S., Forfinski, N.A., Stewart, H.F., and Doran, E.F., 2007, Quaternary geology and sedimentary processes in the vicinity of Six Mile Reef, eastern Long Island Sound: Journal of Coastal Research v. 23, no. 6.


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. Horizontal resolution of the data varies with water depth, but averages 2 m.

  3. How accurate are the heights or depths?

    Vertical resolution is about 0.5% of the water depth.

  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 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

  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 U.S. Geological Survey (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 formatted XYZ data files.


Who wrote the metadata?

Dates:
Last modified: 17-Aug-2007
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 Fri Aug 17 08:37:02 2007