One meter mosaic of acoustic backscatter data acquired using a SWATHplus-H interferometric sonar in Barnegat and Little Egg Inlets, New Jersey by the U.S. Geological Survey in 2012, and 2013 (GeoTIFF image, UTM 18N, WGS 84)

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Frequently anticipated questions:


What does this data set describe?

Title:
One meter mosaic of acoustic backscatter data acquired using a SWATHplus-H interferometric sonar in Barnegat and Little Egg Inlets, New Jersey by the U.S. Geological Survey in 2012, and 2013 (GeoTIFF image, UTM 18N, WGS 84)
Abstract:
In 2011, the US Geological Survey in partnership with the New Jersey Department of Environmental Protection began a multidisciplinary research project to better understand the water quality in Barnegat Bay, New Jersey. This back-barrier estuary is flushed by only three inlets and is experiencing degraded water quality, algal blooms, loss of seagrass, and increases in oxygen stress, macro algae, stinging nettles, and brown tide. The scale of the estuary and the scope of the problems within it necessitate a multidisciplinary approach that includes establishing the regional geology, its physical characteristics, and modeling how the estuary's morphology interacts to affect its water quality. Scientists from USGS Coastal and Marine Geology Program offices in Woods Hole, Massachusetts, and St. Petersburg, Florida, began mapping the seafloor of the Barnegat Bay-Little Egg Harbor estuary in November 2011 and completed in September 2013. With funding from the New Jersey Department of Environmental Protection and logistical support from the USGS New Jersey Water Science Center, they collected data with a suite of geophysical tools, including swath bathymetric sonar for measuring seafloor depth, a sidescan sonar for collecting acoustic-backscatter data (which provides information about seafloor texture and sediment type), subbottom profiler for imaging sediment layers beneath the floor of the estuary, and sediment samples with bottom photographs for ground validation of the acoustic data. More information about the individual surveys conducted as part of the Barnegat Bay Project can be found on the Woods Hole Coastal and Marine Science Center Field activity webpages: 2011-041-FA: http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2011-041-FA 2012-003-FA: http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2012-003-FA 2013-014-FA: http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2013-014-FA 2013-030-FA: http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2013-030-FA
  1. How might this data set be cited?
    U.S. Geological Survey, 2015, One meter mosaic of acoustic backscatter data acquired using a SWATHplus-H interferometric sonar in Barnegat and Little Egg Inlets, New Jersey by the U.S. Geological Survey in 2012, and 2013 (GeoTIFF image, UTM 18N, WGS 84): Data Series 937, 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.

    Andrews, Brian D., Miselis, Jennifer L., Danforth, William W., Irwin, Barry J., Worley, Charles R., Bergeron, Emile M., and Blackwood, Dann S., 2015, Marine geophysical data collected in a shallow back-barrier estuary: Barnegat Bay, New Jersey: Data Series 937, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -74.331299
    East_Bounding_Coordinate: -74.083277
    North_Bounding_Coordinate: 39.813338
    South_Bounding_Coordinate: 39.465727
  3. What does it look like?
    BarnBayInletsBS_1m.jpg (JPEG)
    Thumbnail image of backscatter collected in Barnegat and Little Egg Inlets, Barnegat Bay, NJ. The file is located in the compressed zip file.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 22-Mar-2012
    Ending_Date: 15-Sep-2013
    Currentness_Reference:
    ground condition of individual surveys during backscatter collection in Barnegat Inlet during 2012-003-FA; 20120322; Little Egg Inlet during 2013-030-FA; 20130911-20130915.
  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 38398 x 20945 x 1, type Pixel
    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: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 1.000000
      Ordinates (y-coordinates) are specified to the nearest 1.000000
      Planar coordinates are specified in meters
      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?
    Entity_and_Attribute_Overview:
    There are no attributes associated with a GeoTIFF image. Image pixel values contain acoustic reflectivity values normalized to an 8-bit data range (0-255). Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values). An embedded 3-band colormap with an alpha channel was produced within SonarWiz as a function of the export routine. When viewing this tiff either use the colormap with a no data value of 249, or use a stretched renderer with a min-max of 125 and 1, and an no data value of 0. The mean DN value of this image is 247 and the standard deviation is 14.
    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?
    Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  3. To whom should users address questions about the data?
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov

Why was the data set created?

This mosaic of acoustic backscatter will be used to interpret the sediment composition of Barnegat and Little Egg Inlets and assist in understanding the regional geology of Barnegat Bay, New Jersey.

How was the data set created?

  1. From what previous works were the data drawn?
    Raw SXR files (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw SWATHplus sxr files.

    Type_of_Source_Media: disc
    Source_Contribution:
    SONAR CONFIGURATION: Bathymetry data were acquired using a Systems Engineering and Assessment Ltd (SEA) SWATHplus-H interferometric sonar operating at a frequency of 468 kHz. The sonar transducers were mounted on a rigid pole installed on the bow of the R/V Rafael and was deployed at a depth of 0.7 m below the water line while collecting data. Typical sonar operating parameters include a transmit power of 60%, a transmit length of 34 or 43 cycles, and a sample rate of 4096 samples per channel. SPEED OF SOUND; sound velocity profiles were collected approximately every two hours, or when water properties changed using a hand-deployed sampler. Sound velocity data within the water column was measured using AML Oceanographic SVP Plus profiler during surveys 2011-041-FA and 2012-003-FA, and an AML Oceanographic MINOS-X profiler during 2013-014 and 2013-030.
  2. How were the data generated, processed, and modified?
    Date: 07-Mar-2014 (process 1 of 5)
    Step 1: Import raw SWATHplus-H files to SonarWiz. A new SonarWiz (v. 5.06) project was created with coordinate system defined as Universal Transverse Mercator (UTM), Zone 18 WGS 84. The raw SWATHplus-H files in sxr format were imported to the new SonarWiz project for processing using the "import" menu. The raw files were converted to a common sensor format (CSF) for use in SonarWiz. Person who carried out this activity:
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov
    Date: 10-Mar-2014 (process 2 of 5)
    Step 2: Edit line files. Each line file was reviewed to identify the water column and define the seafloor using bottom tracking algorithms. Once these bottom picks were defined, an empirical gain normalization (EGN) function of 80 units (relative units out of 100) for both port and starboard sides was used to enhance the visual display of the sonar data by optimizing the dynamic range of all backscatter intensity. The across-track range was also adjusted to improve quality of final mosaic my increasing or reducing across track coverage. Additionally the nadir value was set to transparent 1 meter on either side of nadir. This removes the striping at nadir. Sidescan overlap modes was set to "cover up" so that the order of overlapping swaths was user-defined to improve visual quality. Person who carried out this activity:
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov
    Date: 10-Mar-2014 (process 3 of 5)
    Step 3: Export to GeoTIFF. Once all the line files were processed and corrected, they were exported as one mosaic using the export function within SonarWiz (v.5.06) to a 24-bit color range with one meter resolution Producing one backscatter mosaic of Barnegat and Little Egg Inlets (BarnBayInletsBS_1m.tif). Person who carried out this activity:
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    508-457-2310 (FAX)
    bandrews@usgs.gov
    Date: 13-Jul-2016 (process 4 of 5)
    Step 4: Changed incorrect data download links in the Online Linkage and Network_Resource_Name sections. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. 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 5 of 5)
    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?

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

  1. How well have the observations been checked?
    This image is an 8-bit GeoTIFF with a four band imbedded colormap with an alpha channel. Image pixel values contain acoustic reflectivity values normalized to an 8-bit range (0-255). Low-backscatter is represented by dark tones (low values) and high-backscatter is represented by bright tones (high values). No data value = 249.
  2. How accurate are the geographic locations?
    2012-003-FA and 2013-030-FA Real Time Kinematic (RTK) navigation was used to determine the horizontal position (x, and y coordinates) of the GPS antenna mounted above the SWATHplus-H transducers with sub-meter accuracy. A RTK-enabled motion reference unit (Coda Octopus F190) was mounted directly above the sonar transducers and continuously measured vertical displacement (heave) and attitude (pitch and roll) of the vessel during data acquisition. Horizontal offsets between navigation and attitude antennas and the SWATHplus-H transducers were applied during acquisition in the configuration files for the Swath Processor and Coda Octopus software.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This image only includes acoustic backscatter data collected with the SWATHplus-H interferometric sonar within Barnegat and Little Egg Inlets.
  5. How consistent are the relationships among the observations, including topology?
    SWATHplus-H backscatter data were collected simultaneously with depth soundings along all bathymetry survey lines, however, only data collected in Barnegat and Little Egg Inlets were processed for publication. In these areas, the pole-mounted SWATHplus-H backscatter data was processed because it produced better results than the towed sidescan sonars.

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: none
  1. Who distributes the data set? (Distributor 1 of 1)
    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2348 (voice)
    bandrews@usgs.gov
  2. What's the catalog number I need to order this data set? BarnBayInletsBS_1m.zip contains: BarnBayInletsBS_1m.tif, BarnBayInletsBS_1m.jpg browse graphic, and the associated FGDC compliant metadata. To display this mosaic along with the other two in this publication, use the "BarnegatBay Backscatter.lyr" located in the BarnBayBS_1m.zip file.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, 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. 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?
    This Zip file contains a compressed GeoTIFF image and world file. The user must have software capable of uncompressing the zip file and viewing a GeoTIFF image.

Who wrote the metadata?

Dates:
Last modified: 20-Jul-2018
Metadata author:
Brian Andrews
U.S. Geological Survey
Geographer
384 Woods Hole Rd.
Woods Hole, MA
USA

508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@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/midatl/barnegat_bay/BarnBayInletsBS_1m.faq.html>
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