H11045_GEO_5MBATHY.TIF: Color-Encoded Image of 5-m Gridded Hill-Shaded Bathymetry From Long Island Sound off Bridgeport, Connecticut (Geographic)

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Frequently-anticipated questions:

What does this data set describe?

Title:
H11045_GEO_5MBATHY.TIF: Color-Encoded Image of 5-m Gridded Hill-Shaded Bathymetry From Long Island Sound off Bridgeport, Connecticut (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 regridded and interpolated this NOAA bathymetric survey into a complete-coverage acoustic image of the sea floor. The image presented herein covers an area of the sea floor in west-central Long Island Sound off Bridgeport, Connecticut and was produced from data collected during NOAA survey H11045.

This imagery may 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. This bathymetry may also serve as a base map 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?

    Survey, U.S.Geological, 2006, H11045_GEO_5MBATHY.TIF: Color-Encoded Image of 5-m Gridded Hill-Shaded Bathymetry From Long Island Sound off Bridgeport, Connecticut (Geographic): Open-File Report 2005-1145, 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., 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:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -73.304365
    East_Bounding_Coordinate: -73.109031
    North_Bounding_Coordinate: 41.155451
    South_Bounding_Coordinate: 41.020474

  3. What does it look like?

    <http://pubs.usgs.gov/of/2005/1145/graphics/browse_graphics/h11045_geo_bathy.jpg> (JPEG)
    Overview image of NOAA survey H11045

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

    Calendar_Date: 2005
    Currentness_Reference: publication date

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

    Geospatial_Data_Presentation_Form: remote-sensing image

  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 2998 x 3270 x 1, type Pixel

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

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. 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.

  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?

    Please acknowledge NOAA and the NOAA Ship RUDE as the originators of the data from which this data set was derived.

  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
    USA

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

Why was the data set created?

To release a geotiff image of 5 m gridded bathymetry in geographic, generated from NOAA survey H11045 in Long Island Sound off Bridgeport, Connecticut.

How was the data set created?

  1. From what previous works were the data drawn?

    h11045_5m_decimal_degrees_xyz.txt (source 1 of 1)
    National Oceanic and Atmospheric Administration, Unpublished Material, H11045 Bathymetry.

    Type_of_Source_Media: DVD-ROM
    Source_Contribution:
    Original gridded, but not interpolated data. This had resulted in areas of no data between many of the ship's tracks.

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

    Date: 2003 (process 1 of 5)
    The bathymetry data were collected during 2003 as part of NOAA surveys H11044 aboard the NOAA Ship RUDE. The RUDE, which supports NOAA's east-coast nautical charting mission, is outfitted to acquire single-beam bathymetry with an Odom Echotrac DF-3200 duel frequency echosounder and shallow water multibeam bathymetry with a Reson 8125 system. The Reson multibeam system operates at 455 KHz with a 120 degree across track swath and 240 beams along its swath. The multibeam data for these surveys were acquired in XTF (extended Triton data format) and recorded digitally through an ISIS data acquisition system. Once digitally recorded, the XTF data were processed using CARIS HIPS/SIPS software to quality control the data and to incorporate sound velocity and tidal corrections. Vertical datum is mean lower low water.

    Person who carried out this activity:

    National Oceanic and Atmospheric Administration
    c/o Crew of the NOAA Ship RUDE
    Atlantic Hydrographic Branch
    Norfolk, VA 23510
    USA

    Data sources produced in this process:
    • h11045_1m_decimal_degrees_xyz.txt

    (process 2 of 5)
    The original multibeam data sets, which are in ASCII comma-delimited text, do not entirely cover the sea floor because line spacing during acquisition was such that areas of no data often are present between the ship's tracks. Therefore, further processing was conducted at the USGS's Woods Hole Science Center to provide bathymetric datasets with more continuous coverage. First, all non-standardized records were assumed to be bad records and were removed. Subsequently, the PROJ.4 cartographic projections library was used to project the data, the SwathEd software produced by the Ocean Mapping Group at the University of New Brunswick was used to create the grids from the actual sounding data, and GMT (the Generic Mapping Tools) was used to create a 5-m interpolated grid of the bathymetry. Interpolation was achieved during GMT processing by running the data through a block median filter and using a surface generating algorithm with a tension of 0.5. Other parameters were set at default. The grid was projected into Universal Transverse Mercator, Zone 18N.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    GIS Specialist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-548-8700 x2315 (voice)

    Data sources used in this process:
    • h11044_1_5m_decimal_degrees_xyz.txt

    Data sources produced in this process:

    • h11045_bathy5

    Date: 2005 (process 3 of 5)
    A sun-illuminated surface was generated from the interpolated grid using ArcTool box with hill-shading from 270 degrees (a direction parallel to most of the ship's tracks) to minimize artifacts and angle of 45 degrees above the horizon.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    GIS Specialist

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

    Data sources used in this process:
    • h11045_bathy5

    Data sources produced in this process:

    • h11045_hlshd5

    Date: 2005 (process 4 of 5)
    ArcView 3.3 extension grid2image (Image Conversion-Georeferencing) was used to create the color geotiff image. As part of this process, the bathymetry was color coded to user-specified full-spectrum legend colors and the hill-shaded grid was saved as a geotiff image preserving both the legend colors and hill shading.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    GIS Specialist

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

    Data sources used in this process:
    • h11045_hlshd5
    • h11045_bathy5

    Data sources produced in this process:

    • h11045_utm18_5mbathy.tif

    Date: 2005 (process 5 of 5)
    The Blue Marble Geographic Transformer was used to project the UTM zone 18 geotiff image into geographic WGS84.

    Person who carried out this activity:

    Seth Ackerman
    U.S. Geological Survey
    GIS Specialist

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

    Data sources used in this process:
    • h11045_utm18_5mbathy.tif

    Data sources produced in this process:

    • h11045_geo_5mbathy.tif

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

    Beaulieu, E., Poppe, L.J., Paskevich, V.F., Doran, E.F., Chauveau, B.E., Crocker, J.M., Beaver, A.J., and Schattgen, P.T., 2005, Sidescan Sonar Imagery and Surficial Geologic Interpretation of the Sea Floor off Bridgeport, Connecticut: Open-File Report 2005-1162, 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?

    There are no attributes associated with a geotiff image.

  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 a geotiff image of the interpolated and gridded 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 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)

    Larry Poppe
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543

    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: Geotiff image of color-encoded 5-m hill-shaded multibeam bathymetry of NOAA survey H11045 in geographic

  3. What legal disclaimers am I supposed to read?

    Although this data set has been used by the USGS and NOAA, no warranty, expressed or implied, is made by the USGS or NOAA 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 or NOAA in the use of these data or related materials.

  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 "geotiff" images.

Who wrote the metadata?

Dates:
Last modified: 26-Jan-2006
Metadata author:
U.S. Geological Survey
c/o Larry Poppe
Geologist
384 Woods Hole Road
Woods Hole, MA 02543
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 Jan 26 08:18:08 2006