H11250G: 2-m Bathymetric Grid of NOAA Survey H11250 of Eastern Long Island Sound (Geographic)

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Frequently-anticipated questions:

What does this data set describe?

Title:
H11250G: 2-m Bathymetric Grid of NOAA Survey H11250 of Eastern Long Island Sound (Geographic)
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 mulitbeam bathymetric data within specific areas of special interest. The gridded data presented herein covers a roughly 94 km square area of the sea floor in the area known as the Race at the eastern end of Long Island Sound. The original multibeam bathymetric data were collected during October 2003 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 over 560 km of 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 an additional 637 km of survey lines from the shallower areas.

The detailed bathymetic 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?

    U.S. Geological Survey, 2007, H11250G: 2-m Bathymetric Grid of NOAA Survey H11250 of Eastern Long Island Sound (Geographic): Open-File Report 2007-1012, 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., DiGiacomo-Cohen, M.L., Doran, E.F., Smith, S.M., Stewart, H.F., and Forfinski, N.A., 2007, Geologic Interpretation and Multibeam Bathymetry of the Sea Floor in the Vicinity of the Race, Eastern Long Island Sound: Open-File Report 2007-1012, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Other_Citation_Details: 1 DVD-ROM

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -72.154000
    East_Bounding_Coordinate: -71.992004
    North_Bounding_Coordinate: 41.270997
    South_Bounding_Coordinate: 41.188000

  3. What does it look like?

    <http://pubs.usgs.gov/of/2007/1012/data/bathy/grids/geo/h11250_geo_bathy2m/h11250g.gif> (GIF)
    Thumbnail image showing the gray-scale 2-m bathymetric grid from NOAA survey H11250 in geographic.

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

    Calendar_Date: 2003
    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 3966 x 7741 x 1, type Grid Cell

    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 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:
      Depth_System_Definition:
      Depth_Distance_Units: meters

  7. How does the data set describe geographic features?

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?

    Source data were acquired during National Oceanic and Atmospheric Administration (NOAA) survey H11250. Please acknowledge NOAA as the originator of the dataset from which this dataset was derived.

  3. To whom should users address questions about the data?

    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

Why was the data set created?

The purpose of this datalayer is to release a 2-m grid of NOAA survey H11250 in easternmost Long Island Sound and westernmost Block Island Sound. This GIS layer serves a starting point for a geologic study of the area surrounding the Race Long Island Sound. It can be used as a base for interpretative layers and images. This gridded data can be used in ArcMap or ArcView to dramatically display the varied bathymetry and geologic features of the area.

How was the data set created?

  1. From what previous works were the data drawn?

    B370_03_H11250G_dtm2m_interp.gutm (source 1 of 1)
    National Oceanic and Atmospheric Administration, Unpublished Material, B370_03_H11250G_dtm2m_interp.gutm.

    Type_of_Source_Media: DVD-ROM
    Source_Contribution:
    Digital terrain model with 2 m resolution in .gutm format created by National Oceanic and Atmospheric Administration (NOAA). This data format is used for viewing the model with GeoZui3D software.

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

    Date: 2003 (process 1 of 4)
    The multibeam bathymetric data presented herein were collected during October 2003 over a roughly 91 km2 area 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 over 560 km of 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 an additional 637 km of survey lines from the shallower areas. Horizontal resolution of the data varies with water depth, but averages 1-2 m. Vertical resolution is about 0.5% of the water depth.

    Person who carried out this activity:

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

    (757) 441-6726 (voice)
    shep.smith@noaa.gov

    Data sources used in this process:
    • raw data

    Data sources produced in this process:

    • b370_h11250_dtm2m.gutm

    Date: 2004 (process 2 of 4)
    The .gutm file was converted to ASCIIgrid format.

    Person who carried out this activity:

    Chris Polloni
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA 02543-1598

    (508) 548-8700 (voice)
    cpolloni@usgs.gov

    Data sources used in this process:
    • b370_h11250_dtm2m.gutm

    Data sources produced in this process:

    • b370_03.asc

    Date: 2004 (process 3 of 4)
    The ASCIIgrid was converted to ArcGIS GRID format, and then renamed.

    Person who carried out this activity:

    Mary DiGiacomo-Cohen
    U.S. Geological Survey
    Geologist / GIS Analyst
    Long Island Sound Resource Center
    Groton, CT 06340

    (860) 405-9015 (voice)
    mdicohen@usgs.gov

    Data sources used in this process:
    • b370_03.asc

    Data sources produced in this process:

    • B370_03
    • h11250u

    Date: 2006 (process 4 of 4)
    Grid was projected to geographic coordinates using a bilinear interpolation. The resulting grid was then clipped to remove some of the excess area of 'no data' surrounding the bathymetric grid.

    Person who carried out this activity:

    Mary DiGiacomo-Cohen
    U.S. Geological Survey
    Geologist / GIS Analyst
    Long Island Sound Resource Center
    Groton, CT 06340

    860-405-9210 (voice)
    mdicohen@usgs.gov

    Data sources used in this process:
    • h11250u

    Data sources produced in this process:

    • h11250g

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

    Poppe, L.J., DiGiacomo-Cohen, M.L., Smith, S.M., Stewart, H.F., and Forfinski, N.A., 2006, Seafloor character and sedimentary processes in eastern Long Island Sound and Western Block Island Sound: Geo-Marine Letters v. 26, p. 59-68.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    The only attribute value represents gridded bathymetry measured in meters; accuracy of the multibeam system is depth dependent.

  2. How accurate are the geographic locations?

    Navigation was by differential GPS; positional accuracy to less than 10 m.

  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 generate the gridded data. The area is considered complete; the gaps in the data lie in areas inaccessible to the survey vessels (shallow water surrounding islands).

  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 for navigation purposes.

Public domain data are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) and the Connecticut Department of Environmental Protection (CTDEP) as the originators of this dataset.

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

    Larry Poppe
    USGS
    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 - H11250G - ArcGIS grid format bathymetry layer

  3. What legal disclaimers am I supposed to read?

    Although this data set has been used by the U.S. Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), and the Connecticut Department of Environmental Protection (CTDEP), no warranty, expressed or implied, is made by the USGS, NOAA, and the Connecticut DEP 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 these agencies 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 similar to ArcGIS that is capable of reading and processing the data files.

Who wrote the metadata?

Dates:
Last modified: 23-Apr-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 Mon Apr 23 09:14:11 2007