Multibeam bathymetric data collected in Little Egg Inlet and offshore the southern end of Long Beach Island, NJ, during USGS Field Activity 2018-001-FA, using a dual-head Reson T20-P multibeam echo sounder (32-bit GeoTIFF, UTM Zone 18N, NAD 83, NAVD 88 Vertical Datum, 4-m resolution)

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Frequently anticipated questions:

What does this data set describe?

Title:
Multibeam bathymetric data collected in Little Egg Inlet and offshore the southern end of Long Beach Island, NJ, during USGS Field Activity 2018-001-FA, using a dual-head Reson T20-P multibeam echo sounder (32-bit GeoTIFF, UTM Zone 18N, NAD 83, NAVD 88 Vertical Datum, 4-m resolution)
Abstract:
The natural resiliency of the New Jersey barrier island system, and the efficacy of management efforts to reduce vulnerability, depends on the ability of the system to recover and maintain equilibrium in response to storms and persistent coastal change. This resiliency is largely dependent on the availability of sand in the beach system. In an effort to better understand the system's sand budget and processes in which this system evolves, high-resolution geophysical mapping of the sea floor in Little Egg Inlet and along the southern end of Long Beach Island near Beach Haven, New Jersey was conducted from May 31 to June 10, 2018, followed by a sea floor sampling survey conducted from October 22 to 23, 2018, as part of a collaborative effort between the U.S. Geological Survey and Stockton University. Multibeam echo sounder bathymetry and backscatter data were collected along 741 kilometers of tracklines (approximately 200 square kilometers) of the coastal sea floor to regionally define its depth and morphology, as well as the type and distribution of sea-floor sediments. Six hundred ninety-two kilometers of seismic-reflection profile data were also collected to define the thickness and structure of sediment deposits in the inlet and offshore. These new data will help inform future management decisions that affect the natural and recreational resources of the area around and offshore of Little Egg Inlet. These mapping surveys provide high-quality data needed to build scientific knowledge of the evolution and behavior of the New Jersey barrier island system.
Supplemental_Information:
Additional information on the field activities associated with this project are available at https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-001-FA and https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-049-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 20210422, Multibeam bathymetric data collected in Little Egg Inlet and offshore the southern end of Long Beach Island, NJ, during USGS Field Activity 2018-001-FA, using a dual-head Reson T20-P multibeam echo sounder (32-bit GeoTIFF, UTM Zone 18N, NAD 83, NAVD 88 Vertical Datum, 4-m resolution): data release DOI:10.5066/P9C3J33K, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Ackerman, Seth D., Barnhardt, Walter A., Worley, Charles R., Nichols, Alex R., Baldwin, Wayne E., and Evert, Steve, 2021, High-resolution geophysical and geological data collected in Little Egg Inlet and offshore the southern end of Long Beach Island, NJ, during USGS Field Activities 2018-001-FA and 2018-049-FA: data release DOI:10.5066/P9C3J33K, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Ackerman, S.D., Barnhardt, W.A., Worley, C.R., Nichols, A.R., Baldwin, W.E., and Evert, S., 2021, High-resolution geophysical and geological data collected in Little Egg Inlet and offshore the southern end of Long Beach Island, NJ, during USGS Field Activities 2018-001-FA and 2018-049-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9C3J33K.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -74.479874
    East_Bounding_Coordinate: -74.189531
    North_Bounding_Coordinate: 39.579433
    South_Bounding_Coordinate: 39.370229
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5f5f97ee82ce3550e3bff263?name=2018-001-FA_T20P_Bathymetry_4m_NAVD88_browse.jpg (JPEG)
    Thumbnail image of 4-m multibeam echo sounder bathymetry data collected offshore of Long Beach Island, NJ.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 31-May-2018
    Ending_Date: 10-Jun-2018
    Currentness_Reference:
    ground condition during field activity 2018-001-FA: 20180531-20180610
  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 5717 x 6232 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: 18N
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -75
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000
      False_Northing: 0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 4.0
      Ordinates (y-coordinates) are specified to the nearest 4.0
      Planar coordinates are specified in meters
      The horizontal datum used is GCS_North_American_1983_2011.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: North American Vertical Datum of 1988
      Depth_Resolution: 0.1
      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:
    Elevation values in 32-bit GeoTIFF format. Data values represent depths referenced to the North American Vertical Datum of 1988 (NAVD 88).
    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?
  3. To whom should users address questions about the data?
    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

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

Why was the data set created?

The purpose of this dataset is to provide a high-resolution digital elevation model (DEM) of the seabed in the study area referenced to the North American Vertical Datum of 1988 (NAVD 88). In conjunction with other geophysical and sample data, this bathymetry dataset will be used to investigate the morphology and geologic framework of the sea floor and coastal environment.

How was the data set created?

  1. From what previous works were the data drawn?
    Reson T20P multibeam echo sounder raw bathymetry and backscatter (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw MBES data in s7k format.

    Type_of_Source_Media: disc
    Source_Contribution:
    Multibeam echo sounder (MBES) bathymetry and backscatter data were collected using dual-head Reson T20-P sonars. The pair of mills cross transmit and receive arrays were mounted side-by-side within a bracket that oriented them at opposing 30-degree angles (relative to horizontal). The bracket was pole-mounted on the starboard side of the R/V Petrel so that the sonar arrays were oriented athwart ships (primary and secondary arrays facing outward and down to port and starboard, respectively) and located approximately 1.235 m below the waterline when deployed. Vessel navigation and attitude data were acquired using an Applanix POS MV Wavemaster (model 220, V5) configured with two AeroAntenna Technologies GPS antennas located at either end of a 2-m baseline, which was oriented fore and aft and mounted atop the MBES pole approximately midships on the starboard side of vessel, and the wetpod MRU mounted atop the sonar bracket just aft of the pole. An AML Micro X SV mounted on the sonar bracket monitored sound speed near the sonars during acquisition, and an ODIM MVP30 moving vessel profiler (MVP), mounted on the stern, was used to collect water column sound speed profiles at 1 to 2 hour intervals while underway (See shapefile 2018-001-FA_MVP_data.shp available from the larger work citation). The Reson SeaBat User Interface (version 5.0.0.6) was used to control the sonars, which were operated in intermediate mode at full power (220 db), with frequency-modulated pulses between 200 to 300 kHz. The range of the 1024 across track beams formed by the sonars were adjusted manually depending on water depth, and resulted in combined swath widths of 60 to 200 meters or typically 3 to 6 times the water depth. Data were monitored and recorded using the Reson SeaBat User Interface (UI) (version 5.0.0.6) and Hypack/Hysweep (version 2017, 17.1.3.0). The SeaBat User Interface logged the navigation, attitude, bathymetry, time-series backscatter, and water column data to s7k format files for each sonar. The line files were created by the Reson UI using the following naming convention: YYYYMMDD_HHMMSS_M/S. The line files were appended with a "M" and "S" suffix to denote the port (primary) "M" and "S" starboard (or secondary) sonar heads. HYSWEEP also was used to log the navigation, attitude, and bathymetry data for both sonars to a single HSX format file. The Reson SeaBat User Interface s7k data were used to produce the final processed backscatter mosaic and bathymetry grid.
  2. How were the data generated, processed, and modified?
    Date: Sep-2018 (process 1 of 3)
    PROCESSING STEP 1: CARIS HIPS DATA PROCESSING. Multibeam bathymetry processing within CARIS HIPS (version 10.4.1) during the survey consisted of the following flow:
    1) Vessel configuration files were created in CARIS for the port ("M"=main, or primary) and starboard ("S"=secondary) sonars (Petrel_dual_T20P_s7k_M.hvf, and Petrel_dual_T20P_s7k_S.hvf) which included relevant, linear and angular installation offsets for each T20-P unit as well as vendor specified uncertainty values for each of the survey sensors.
    2) A CARIS HIPS project (version 10.4.1) was created with projection information set to Universal Transverse Mercator (UTM) Zone 18N, WGS 84. Separate HIPS projects were created for the Port (M), and Starboard (S) line files using the two vessel configuration files in #1 above.
    3) Each Reson s7k file (M and S) were imported to the new CARIS projects (M and S respectively) using the Import/Conversion Wizard.
    4) Delayed heave data from raw POS MV files were used to update HIPS survey lines using the import auxiliary data function.
    5) Navigation was reviewed and edited as needed using the Navigation Editor tool.
    6) Sound velocity correction was applied using the CARIS algorithm, a master SVP file containing all the sound velocity profiles collected during the survey and specifying the nearest in distance method, delayed heave source, and use surface sound speed.
    7) Data were merged selecting no tide and the delayed heave source.
    8) 4-m resolution Swath Angle Weighted (SWATH) surfaces were created to incorporate all the files (M and S) as they were processed, and the SWATH surfaces were reviewed for inconsistencies and anomalies.
    9) The swath and subset editors were used to remove spurious points through manual editing and filter application, and the refraction editor was used to adjust sound speed values in areas where sound velocity data did not adequately correct depth profiles, which were obviously influenced by local anomalies in speed of sound through the water column.
    10) Survey lines adjusted for refraction anomalies were remerged, and the respective SWATH surfaces were recomputed to reflect the changes. Processing during the survey was primarily focused on QA/QC during acquisition. Editing processes did require trial and error and were at times iterative. This process step was completed over the course of several months beginning with work done during the survey in June 2018; the date on this process step indicated below is the last day described processing was done. The contact person for this and all subsequent processing steps below is Seth Ackerman. Person who carried out this activity:
    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov
    Date: 22-Dec-2020 (process 2 of 3)
    PROCESSING STEP 2: APPLY POST PROCESSED SBET FILES AND EDIT SOUNDINGS.
    Post-survey processing within CARIS HIPS (version 11.3.0) consisted of the following flow: 1) Delayed heave data from raw POS MV files were re-imported. Post-processed navigation, vessel attitude, and GPS height data from POSPac SBET files, and post-processed RMS attitude error data from POSPac smrmsg files were used to update HIPS survey lines using the import auxiliary data function.
    2) Navigation source was set to Applanix SBET, and navigation was reviewed and edited as needed using the Navigation Editor tool.
    3) Data were remerged. In CARIS version 11 the merge function is now called Georeference Bathymetry. In this step, the sound velocity correction is applied, the GPS tide is computed, the delayed heave is selected as heave source, and a single datum value of 0 m (vertically referencing the data to the WGS 84 Ellipsoid) is chosen.
    4) A 4-m resolution SWATH surface using both the M and S files was created using the Swath Angle method.
    7) Additional editing was conducted using the swath and subset editors to minimize inconsistencies and artifacts, and a final SWATH surface was created to reflect the changes. Finally, small "no data" holidays were filled using two iterations of the "Fill Raster Holiday" tool and a 5x5 cell filter using data from a minimum of 4 neighboring cells.
    Date: 22-Dec-2020 (process 3 of 3)
    PROCESSSING STEP 3: EXPORT AND TRANSFORM TO NAVD 88.
    The CARIS HIPS SWATH surface was exported as 4-m per pixel ASCII files referenced to UTM Zone 18N, WGS84 and ellipsoidal heights. The National Oceanic and Atmospheric Administration's Vertical Datum Transformation tool (VDatum v.4.1.2) was used to transform surfaces to the North American Vertical Datum of 1988 (NAVD 88). The process required transformation of the horizontal and vertical reference frames from WGS84 (using ITRF2008) and ellipsoidal heights to UTM Zone 18N, North American Datum of 1983 (NAD 83) and NAVD 88 orthometric heights (all in meters) using the default geoid model. The resulting ASCII raster was opened in Global Mapper (version 19.0) and converted into a 32-bit floating point GeoTIFF (2018-001-FA_T20P_Bathymetry_4m_NAVD88.tif) using Export, Export Elevation Grid Format, GeoTIFF.
  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?
    Navigation data were acquired using the WGS 84 coordinate system with an Applanix POS MV Wavemaster (model 220, V5), which blends Global Navigation Satellite Systems (GNSS) with acceleration data from a Motion Reference Unit (MRU) and GPS azimuthal heading. The POS MV was configured with two AeroAntenna Technologies GPS antennas located at either end of a 2-m baseline, which was oriented fore and aft and mounted atop the MBES pole, approximately midships on the starboard side of vessel. DGPS positions were obtained from the primary antenna located on the forward end of the baseline, and the positional offsets between the antenna and the navigational reference point (the POS MV IMU) were accounted for in the Applanix POSView (version 8.60) acquisition software. DGPS positions are horizontally accurate to 0.5 - 2 meters, but accuracy can increase to less than 10 cm after post-processing with Applanix POSPac (version 8.1).
  3. How accurate are the heights or depths?
    Vertical accuracy of the raw data based on system specifications may be approximately 1 percent of water depth (ranging from 0.5 to 1.5 meters based on the water depth range of less than 2 meters to approximately 20 meters within the survey area). The Applanix Wavemaster POS MV Attitude and Positioning system, used to correct for vessel roll, pitch, heave, and yaw, has a theoretical vertical accuracy of a few mm. Post-Processed Kinematic (PPK) GPS height corrections (from Applanix POSPac smoothed best estimate of trajectory (SBET) files) were used to reference soundings to the World Geodetic System 1984 (WGS 84) ellipsoid and remove water depth fluctuations in lake levels during the survey. Two hundred thirty-seven sound speed profiles acquired with an ODIM MVP30 moving vessel profiler (MVP) were used during processing to minimize acoustic refraction artifacts in the bathymetry data. Changes in vessel draft due to water and fuel usage were not considered.
    Additionally, uncertainty associated with the vertical transformation of the bathymetric grid from WGS 84 (ITRF 2000) to the North American Vertical Datum of 1988 (NAVD 88) using VDatum transformation tool (NOAA) is approximately 7.6 cm as calculated by the VDatum tool (v. 4.1.2).
  4. Where are the gaps in the data? What is missing?
    Data were collected on the following dates: 20180531-20180610 (Julian day 151-161); bathymetry data from 20180531 (Julian day 151) were processed for performing the patch test to calibrate the multibeam sonar but these data were not incorporated into the final bathymetry dataset since the same area was re-occupied on subsequent survey days. No data were collected on 20180603 (June 3; Julian day 154) due to rough sea-state.
  5. How consistent are the relationships among the observations, including topology?
    This grid represents processed dual-head Reson T20-P multibeam echo sounder (MBES) bathymetry data gridded at 4-m resolution. Quality control and data processing were conducted to remove spurious points and reduce sound speed artifacts (refraction) using Computer Aided Resource Information System (CARIS) Hydrographic Information Processing System (HIPS; version 10.4.1). Despite this processing, small areas of vessel motion and refraction artifacts remain in the data. Small "no data" gaps exist throughout the dataset. These are the result of editing the artifacts and, in some areas, eliminating low quality soundings. In addition, gaps exist in shallow areas where underwater obstructions created hazards for the safe navigation of the survey vessel.
    While navigation and attitude data in the bathymetry data and coincident backscatter data (see larger work citation https://doi.org/10.5066/P9C3J33K) are identical the extents of the processed bathymetry grid and backscatter mosaic differs slightly due to differences in processing.

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:
Public domain data from the U.S. Government are freely distributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset. These data are not to be used for navigation.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    U.S. Geological Survey
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? Multibeam echo sounder 4-m bathymetry data collected off southern Long Beach Island, New Jersey during USGS Field Activity 2018-001-FA, using a dual-head Reson T20-P multibeam echo sounder: includes the GeoTIFF image 2018-001-FA_T20P_Bathymetry_4m_NAVD88.tif, world file 2018-001-FA_T20P_Bathymetry_4m_NAVD88.tfw, the browse graphic 2018-001-FA_T20P_Bathymetry_4m_NAVD88_browse.jpg, and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata files (2018-001-FA_T20P_Bathymetry_4m_NAVD88_meta.xml).
  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. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), and have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, firm, or product 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?
    To utilize these data, the user must have software capable of viewing GeoTIFF files.

Who wrote the metadata?

Dates:
Last modified: 22-Apr-2021
Metadata author:
Seth Ackerman
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA
USA

508-548-8700 x2315 (voice)
508-457-2310 (FAX)
sackerman@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/SB_data_release/DR_P9C3J33K/2018-001-FA_T20P_Bathymetry_4m_NAVD88_meta.faq.html>
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