Multibeam bathymetric data collected in the vicinity of Woods Hole, Massachusetts, during USGS Field Activity 2021-037-FA using a dual-head Teledyne Seabat T20-R multibeam echo sounder (32-bit GeoTIFF, UTM Zone 19N, WGS 84, GEOID 18 (MSL) Vertical Datum, 50cm resolution)

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Frequently anticipated questions:

What does this data set describe?

Title:
Multibeam bathymetric data collected in the vicinity of Woods Hole, Massachusetts, during USGS Field Activity 2021-037-FA using a dual-head Teledyne Seabat T20-R multibeam echo sounder (32-bit GeoTIFF, UTM Zone 19N, WGS 84, GEOID 18 (MSL) Vertical Datum, 50cm resolution)
Abstract:
In November 2021, the U.S. Geological Survey collected high-resolution multibeam sonar data in the vicinity of Eel Pond, in Woods Hole, Massachusetts using a dual-head Teledyne Seabat T20-R multibeam echo sounder (MBES). The main objective of this survey was to evaluate new sonar system features prior to their use in future field activities. In addition to bathymetry and relative acoustic backscatter data, normalized acoustic backscatter data were also collected. Unlike relative backscatter data, normalized backscatter data compensate for adjustments made to sonar power, gain, absorption, spreading, and frequency parameters made during acquisition. In order for backscatter intensity levels to remain consistent along survey lines, and from line to line, relative backscatter data require that minimal adjustments are made to these parameters during acquisition, which can degrade the sonar performance for a given survey site. However, the ability to allow the sonar acquisition software to change sonar parameters based on variations in bathymetry and the survey environment during acquisition allows these parameters to be optimized. Having these parameters optimized for this survey allowed the USGS to evaluate this new normalized backscatter capability to ensure the collected backscatter intensity levels were referenced to a factory calibrated level.
Eel Pond in Woods Hole, MA was chosen as a test area for its proximity to the USGS Coastal and Marine Science Center. It provides a variety of substrates on which to evaluate the performance of the sonar, and bathymetric/backscatter data of this area may prove useful to other projects and institutions in the area.
Supplemental_Information:
Data were collected using the R/V Rafael, owned and operated by the USGS Woods Hole Coastal and Marine Science Center. Additional information on the field activity is available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-037-FA.
  1. How might this data set be cited?
    Moore, Eric M., Danforth, William W., Nichols, Alex R., and Worley, Charles R., 20241220, Multibeam bathymetric data collected in the vicinity of Woods Hole, Massachusetts, during USGS Field Activity 2021-037-FA using a dual-head Teledyne Seabat T20-R multibeam echo sounder (32-bit GeoTIFF, UTM Zone 19N, WGS 84, GEOID 18 (MSL) Vertical Datum, 50cm resolution): data release DOI:10.5066/P13XQBUC, 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.

    Moore, Eric M., Danforth, William W., Nichols, Alex R., and Worley, Charles R., 2024, Multibeam data collected in the vicinity of Eel Pond, Woods Hole, Massachusetts, during field activity 2021-037-FA using an Integrated Dual-Head Teledyne Reson T20-R echosounder: data release DOI:10.5066/P13XQBUC, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Moore, E.M., Danforth, W.W., Nichols, A.R., and Worley, C.R., 2024, Multibeam data collected in the vicinity of Eel Pond, Woods Hole, Massachusetts, during field activity 2021-037-FA using an Integrated Dual-Head Teledyne Reson T20-R echosounder: U.S. Geological Survey data release, https://doi.org/10.5066/P13XQBUC
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.674692
    East_Bounding_Coordinate: -70.668401
    North_Bounding_Coordinate: 41.527612
    South_Bounding_Coordinate: 41.521188
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/663e403fd34eaf9729f7ae0b?name=2021-037-FA_ResonT20R_Bathymetry_50cm_browse.jpg (JPEG)
    Thumbnail image of 50cm multibeam echo sounder bathymetry data collected within Eel Pond, Woods Hole, MA.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 10-Nov-2021
    Currentness_Reference:
    data were collected on the following date: 20211110 (Julian day 314).
  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 1408 x 1024 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: 19N
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -69
      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 0.5
      Ordinates (y-coordinates) are specified to the nearest 0.5
      Planar coordinates are specified in meters
      The horizontal datum used is WGS 84 (G1150).
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: GEOID 18
      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 elevations referenced to the gravimetric model GEOID 18, and range from -1.6 to -22.1 meters below the GEOID.
    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)
    • Eric M. Moore
    • William W. Danforth
    • Alex R. Nichols
    • Charles R. Worley
  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?
    U.S. Geological Survey
    Attn: Eric Moore
    Physical Scientist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2294 (voice)
    508-457-2310 (FAX)
    emoore@usgs.gov

Why was the data set created?

The purpose of this raster depth grid is to provide a high-resolution digital elevation model (DEM) of the sea floor of Woods Hole, MA referenced to the NGS gravimetric Geoid 18 model.

How was the data set created?

  1. From what previous works were the data drawn?
    RAW Teledyne T20-R MULTIBEAM ECHO SOUNDER FILES (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw MBES data in s7k format (.s7k).

    Type_of_Source_Media: disc
    Source_Contribution:
    Multibeam echo sounder (MBES) bathymetry and backscatter data were collected using dual-head Teledyne T20-R sonars connected to the topside Teledyne Integrated Dual Head (IDH) processor.. The pair of mills cross transmit and receive arrays were mounted within a single bracket that oriented arrays at opposing 30-degree angles (relative to horizontal). The bracket was pole-mounted on the starboard side of the R/V Rafael 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 athwartship and mounted atop the aft end of the cabin. The MBES pole was positioned on the aft-starboard side of vessel, and the wetpod MRU was mounted atop the sonar bracket just aft of the pole and used as the NRP for the survey. An AML Micro X SV mounted on the sonar bracket monitored sound speed near the sonars during acquisition, and an AML AML-3 LGR SVPT was used to collect a water column sound speed profile during the survey day which was saved in a text file using the CARIS SVP format. The Teledyne SeaBat User Interface (version 5.0.0.18) was used to control the sonars, which were operated in intermediate mode at full power (220 dB), with frequency-modulated pulses at 400 kHz. The range of the 512 across track beams formed by the sonars were adjusted automatically depending on water depth and resulted in combined swath widths typically 6-8 times the water depth. Data were monitored and recorded using the Teledyne SeaBat User Interface (UI) (version 5.0.0.18) and Hypack/Hysweep (v. 2021). The SeaBat User Interface logged the navigation, attitude, bathymetry, time-series relative and normalized backscatter, and surface sound speed data to s7k format files. The s7k line files were created by the Teledyne UI using the following naming convention: YYYYMMDD_HHMMSS.s7k. In addition to the source produced s7k format, each line was recorded into a HYPACK/HYSWEEP format (v. 2021).
  2. How were the data generated, processed, and modified?
    Date: 10-Oct-2023 (process 1 of 3)
    PROCESSING STEP 1: QPS Qimera DATA PROCESSING.
    Multibeam bathymetry processing within QPS Qimera software (version 2.5.4) of data collected during the survey consisted of the following flow:
    1) A new Qimera project was created on disk using UTM zone 19N, WGS84 as the horizontal reference frame.
    2) Raw T20R s7k files were imported into Qimera project using the Source/Add Raw Sonar Files menu and converted to the Qimera QPD format. This step creates a new vessel file which was named Rafael_IDH.
    3) The Rafael vessel file was edited using the Qimera Vessel Editor and updated to reflect the offsets between the NRP and both the starboard and port transmit/receive transducer arrays. The draft of the NRP below the water line was also entered into the configuration.
    4) Delayed heave data from raw POS MV files (.000) were imported using the Source/Add Binary Navigation Files menu. Using data from these files, a new motion system reference was created (POS_TrueHeave) selecting the true heave checkbox. This reference system was automatically added to the existing vessel file.
    5) The collected sound velocity profile data was imported into the Qimera project using the Source/Input SVP dialog and selecting the CARIS formatted sound velocity data file.
    6) Using the Tools/Edit Processing Settings dialog, the vertical referencing tab was selected and the delayed heave source priorities were set to use the true heave from the raw POS MV files.
    7) Using the Tools/Edit Processing Settings dialog, the sound velocity tab was selected and the sound velocity strategy was updated using the "specific sound velocity profile" checkbox referencing the imported sound velocity data values. The surface sound speed priority was set to the surface sound speed collected by the AML sensor mounted on the sonar bracket, and this value was selected as the first entry in the raytrace profile.
    8) A preliminary, 50 centimeter resolution dynamic surface was created and reviewed for inconsistencies and anomalies. The Qimera swath editor and 3D editor was used to remove spurious points through manual editing and filter application. Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2274 (voice)
    508-457-2310 (FAX)
    bdanforth@usgs.gov
    Date: 12-Oct-2023 (process 2 of 3)
    PROCESSING STEP 2:APPLY POST PROCESSED SBETs ANND FINAL EDITS.
    1) Post-processed navigation, vessel attitude, and GPS height data from the POSPac Smoothed Best Estimate of Trajectory (SBET) file (sbet_Mission 1.out), and post-processed RMS vessel attitude error data from the POSPac smrmsg file were imported using the Source/Add Binary Navigation Files menu. Using data from these files, a new motion system reference (POS_MOTION) was created selecting the motion checkbox, and a new position system reference was created (POS_POSITION) selecting the position and height checkboxes. These two reference systems were automatically added to the existing vessel file.
    2) Using the Tools/Edit Processing Settings dialog, the vertical referencing tab was selected and the vertical referencing method was changed from "None" to "RTK (Accurate Height)" and the POS_POSITION checkbox was selected as the priority. The position, motion, heading tab was then selected and the SBET processed position/motion values were applied by selecting the following:
    The position source priorities were changed to the POS_POSITION reference. The motion source priorities were changed to the POS_MOTION reference. The heading source priorities were changed to the POS_MOTION reference.
    The dynamic grid surface was then automatically updated to reflect the new position/motion processed values, and the soundings were now vertically referenced to the WGS 84 ellipsoid.
    3) The equipotential surface model, GEOID18, was downloaded from the National Geodetic Survey (NGS) website. This gravimetric geoid model approximates mean sea level (MSL) and is consistent with the North American Vertical Datum of 1988 (NAVD 88). This binary grid was directly imported into ArcGIS Pro v3.1 and exported to a 32-bit floating point geotiff.
    4) The 32-bit GEOID18 geotiff was imported into Qimera and converted to an internal Qimera grid format.
    5) Using the Tools/Edit Processing Settings dialog, the vertical referencing tab was selected and a separation model (GEOID 18 model from the NGS) from step 9 was added to the vertical geodetic offset portion of the dialog. The line files were reprocessed using this model in conjunction with ellipsoidal heights, referencing each sounding to the GEOID 18 gravimetric model which is consistent with MSL for the Woods Hole area.
    6) Exported a final depth grid out of Qimera as a 32bit floating point Raster (2021-037-FA_ResonT20R_Bathymetry_50cm.tif).
    7) Exported the final edited line files into the GSF format for backscatter mapping in FMGT (see backscatter process steps). Person who carried out this activity:
    U.S. Geological Survey
    Attn: William W. Danforth
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2274 (voice)
    508-457-2310 (FAX)
    bdanforth@usgs.gov
    Date: 16-Jan-2025 (process 3 of 3)
    The metadata was edited to fix an author middle initial in the larger work citation (20250116). Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Geologist
    384 Woods Hole Rd.
    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?
    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) data, 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 athwartship and mounted atop the aft end of the cabin. DGPS positions were obtained from the primary antenna located on the starboard end of the baseline, and the positional offsets between the primary antenna and the navigational reference point (NRP, the POS MV IMU) were accounted for in the Applanix POSView (version 11.00) acquisition software. DGPS positions are horizontally accurate to 0.5 - 2 meters, but accuracy increases 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 the sonar system specifications is approximately 1 percent of water depth (ranging from 0.05 to 0.2 meters based on the water depth of less than 3 meters to approximately 20 meters within the survey area). Used in conjunction with the Applanix Wavemaster POS MV Attitude and Positioning system to correct for vessel GPS height, roll, pitch, heave, and yaw, a theoretical vertical accuracy of less than a centimeter is obtained using Post-Processed Kinematic (PPK) corrections (from Applanix POSPac v8.1 smoothed best estimate of trajectory (SBET) files). Changes in vessel draft due to water and fuel usage were not considered.
  4. Where are the gaps in the data? What is missing?
    Data collected along 5 sonar calibration lines are not included in this grid. .
  5. How consistent are the relationships among the observations, including topology?
    This grid represents processed dual-head Teledyne Seabat T20-R multibeam echo sounder (MBES) bathymetry data gridded at 50 centimeter resolution. Quality control and data processing were conducted to remove spurious points and reduce sound speed artifacts (refraction) using Quality Positioning Services (QPS) hydrographic software Qimera (v 2.5.4). What appear to be vertical artifacts are actually the Woods Hole Oceanographic Institution (WHOI) dock pilings, mooring chains in Eel Pond, the bulkhead going under the Water Street bridge, as well as other infrastructure items present along Eel Pond and surrounding the Steamship Authority docks. These items were inspected to ensure quality and retained in the bathymetric grid. Other noticeable artifacts include small abrupt steps in bathymetric values between survey lines, most notably in Great Harbor, that are present due to inadequate sound velocity profiling.

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 re-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
    Denver Federal Center
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? Multibeam bathymetric data collected in the vicinity of Eel Pond, Woods Hole, MA during USGS Field Activity 2021-037-FA using a dual-head Teledyne T20-R multibeam echo sounder: includes the GeoTIFF image 2021-037-FA_ResonT20R_Bathymetry_50cm.tif, the browse graphic 2021-037-FA_ResonT20R_Bathymetry_50cm_browse.jpg, and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file (2021-037-FA_ResonT20R_Bathymetry_50cm_meta.xml).
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (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.
  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: 16-Jan-2025
Metadata author:
U.S. Geological Survey
Attn: Eric Moore
Geographer
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2294 (voice)
(508) 457-2310 (FAX)
whsc_data_contact@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_P13XQBUC/2021-037-FA_ResonT20R_Bathymetry_50cm_meta.faq.html>
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