2 meter Arc Raster grid of bathymetry acquired along cross lines using a SEA Ltd. SWATHplus-H interferometric sonar within Barnegat Bay New Jersey by the U.S. Geological Survey in 2011, 2012, and 2013 (Esri binary grid, UTM 18N, WGS 84)

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Frequently anticipated questions:


What does this data set describe?

Title:
2 meter Arc Raster grid of bathymetry acquired along cross lines using a SEA Ltd. SWATHplus-H interferometric sonar within Barnegat Bay New Jersey by the U.S. Geological Survey in 2011, 2012, and 2013 (Esri binary grid, UTM 18N, WGS 84)
Abstract:
Water quality in the Barnegat Bay-Little Egg Harbor estuary along the New Jersey coast is the focus of a multidisciplinary research project begun in 2011 by the U.S. Geological Survey (USGS) in partnership with the New Jersey Department of Environmental Protection. This narrow estuary is the drainage for the Barnegat Watershed and flushed by just three inlets connecting it to the Atlantic Ocean, is experiencing degraded water quality, algal blooms, loss of seagrass, and increases in oxygen -depletion events, seaweed, stinging nettles, and brown tide. The scale of the estuary and the scope of the problems within it necessitate a multidisciplinary approach that includes characterizing its physical characteristics (for example, depth, magnitude and direction of tidal currents, distribution of seafloor and subseafloor sediment) and modeling how the physical characteristics interact to affect the estuary's 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. 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, 2 meter Arc Raster grid of bathymetry acquired along cross lines using a SEA Ltd. SWATHplus-H interferometric sonar within Barnegat Bay New Jersey by the U.S. Geological Survey in 2011, 2012, and 2013 (Esri binary grid, 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: -74.318123
    East_Bounding_Coordinate: -74.042914
    North_Bounding_Coordinate: 40.070850
    South_Bounding_Coordinate: 39.560456
  3. What does it look like?
    bbtl2m.jpg (JPEG)
    Thumbnail image of tie-line bathymetry collected with 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: 01-Nov-2011
    Ending_Date: 16-Sep-2013
    Currentness_Reference:
    ground condition of individual surveys during bathymetry collection: 20111101-20111107; 20120321-20120408; 20130313-20130326; 20130911-20130916.
  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 28221 x 11520 x 1, type Grid Cell
    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 2.000000
      Ordinates (y-coordinates) are specified to the nearest 2.000000
      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.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Bathymetric depth values in Esri ArcRaster format. Data values represent depth in meters referenced to the North American Vertical Datum of 1988 (NAVD88). Depth range min: -7.72, max:-0.75.
    Entity_and_Attribute_Detail_Citation: Esri

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?

The purpose of this bathymetric grid is to serve as internal quality control by crossing the main survey lines at or near 90 degree angle to check for constancy in tides and to "tie" all the lines together. Most of the survey lines in this grid were not used in the bbbath2m grid published in this report, but can be used in conjunction with the seismic profiles collected during the same line.

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. TIDES: Soundings were referenced to the North American Vertical Datum of 1988 (NAVD 88) using 1-minute averaged RTK-GPS sea-surface elevation data.
  2. How were the data generated, processed, and modified?
    Date: 2013 (process 1 of 6)
    Step 1:Process GPS Tides Data for all three surveys: Depths were corrected to North American Vertical Datum of 1988 (NAVD88)) using the 1 second RTK-GPS heights from the GPS receiver mounted over the SWATHplus-H sonar head. Two scripts were used to extract the navigation and described below: Script "getNovatelTides": extracts the "TID" record from each Hypack line file "parseHypackNovatelTides.awk": calculates the average TID value for every two minutes. Each day was appended to a master tide file in CARIS format ("SurveyName"Master.tid) and merged into the line files in Processing Step #3 below. 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: 2013 (process 2 of 6)
    Step 2: Raw to processed conversion for all four surveys. Each raw SWATHplus bathymetric sonar file (*.sxr) was converted to a SWATHplus processed file (*.sxp) using Swath Processor software (v. 3.07). During the conversion process, sound velocity profiles were applied for the speed of sound within the water column and bathymetric filters were applied. 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: 2013 (process 3 of 6)
    Step 3: SWATHplus to CARIS HIPS Conversion: A new CARIS HIPS project (v. 7.2) was created for each of the four surveys with projection information set to Universal Transverse Mercator (UTM) Zone 18 North, WGS 84. Each processed file (*.sxp) was imported to the new HIPS project using the import/conversion wizard. The line files for each day were merged with the Mastertide file (SurveyNameMasterTide.tid) to reference each line to NAVD 88. A 2-meter Bathymetric and Statistical Error (BASE) surface was created from the tie line files for each day. The BASE surface for each day was reviewed for an inconsistencies or data anomalies. Navigation was edited as needed using the navigation editor tool in HIPS. Filters were applied to each line including beam-to-beam slopes (1 degree) and an across track distance of 3-4 times water depth. For a nadir depth of 3 meters an across track filter of 3 times water depth would reduce the swath coverage to 9 meters on each side for a total swath coverage of 18 meters. 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: 28-Jan-2014 (process 4 of 6)
    Step 4. Final surface creation. Tie and transit lines for each Julian Day were reviewed using HIPS Swath Editor, finalized, and added to the surface for each of the four surveys. Output surfaces: 2011_041_2m_tl.csar, 2012_003_2m_tl.csar, 2013_014_2m_tl.csar, 2013_030_2m_tl.csar where the "tl" defines these surfaces as using the tielines only. Surfaces were combined in CARIS Base Editor (v. 4.0) using the "combine" tool and "Data Start Date is least" rule for overlapping cells. This rule condition means that earlier surveys have importance over later surveys where they may overlap. Final output surface= BarnBayOFR2m.csar. This surface was then converted to an ascii raster (bbtl2m.asc) using the "export surface to Esri ASCII Raster" tool within Base Editor (v. 4.0). Ascii file was then imported to ArcGIS (v. 9.3.1) using the "ASCII to Raster" tool within the Conversion toolbox to produce the final 32-bit floating point grid (bbtl2m). 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: 06-Jul-2016 (process 5 of 6)
    Step 5: Changed incorrect data download links in the Online_linkage and Network_Resource_Name sections. 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: 20-Jul-2018 (process 6 of 6)
    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?
  2. How accurate are the geographic locations?
    Two different navigation systems (DGPS and RTK) were used to record horizontal positions of the bathymetric sonar. 2011-041-FA and 2013-014-FA: Differential Global Positioning System (DGPS) 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 motion reference unit (Coda Octopus F180) 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 recorded and applied during acquisition in the configuration files for the Swath Processer and Coda Octopus software. Differential corrections were obtained real-time via the Wide Area Augmentation System (WAAS) providing horizontal accuracy of 1-2 meters. 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?
    A motion reference unit was mounted directly above the sonar transducers and continuously measured vertical displacement (heave) and attitude (pitch and roll) of the vessel during data acquisition. A Coda Octopus F180 motion reference unit was used for survey 2011-041-FA and 2013-014-FA. During surveys 2012-003-FA and 2013-030-FA a Coda Octopus F190 was used. Vertical 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. Vertical accuracy of the raw data may approximate 1 percent of water depth, based on SWATHplus interferometric sonar system specifications, which translates to 0.1 to 0.23 meters within the Barnegat Bay survey area. Real Time Kinematic (RTK)-GPS was used to continuously measure changes in sea-surface elevations relative to the North American Vertical Datum (NAVD 88) with decimeter-scale accuracies. Tide-correction was applied during post-processing (see process steps). Refraction artifacts were minimized by sound velocity profiles throughout the survey area to model the spatial and temporal variability of sound velocity structure of the water column. Changes in vessel draft due to fuel and water usage were not considered.
  4. Where are the gaps in the data? What is missing?
    This grid includes data collected along seismic tie lines and some transit lines that are not included in the "bbbath2m" grid published in this report. http://pubs.usgs.gov/ds/0937/downloads/shapefile/BarnBayBathTrks.zip
  5. How consistent are the relationships among the observations, including topology?
    Each line used to produce this grid has been reviewed and edited to remove inaccurate soundings.

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: These data are not for navigational use.
  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? bbtl2m.zip: contains the Esri binary grid bbtl2m which requires the grid folder and the associated info folder, bbtl2m.jpg browse graphic, and the associated FGDC metadata
  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?
    The grid contained in the .zip file is available as an Esri binary grid. To utilize this data, the user must have a GIS software package capable of reading an Esri binary grid.

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/bbtl2m.faq.html>
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