Single-beam bathymetric data in Pea Island National Wildlife Refuge, North Carolina in November 2020 and April, September, and October 2021

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Frequently anticipated questions:

What does this data set describe?

Title:
Single-beam bathymetric data in Pea Island National Wildlife Refuge, North Carolina in November 2020 and April, September, and October 2021
Abstract:
The data in this part of the release are bathymetry data collected in the nearshore using single-beam echosounders mounted on surf capable self-righting electric autonomous survey vehicles at the USGS DUring Nearshore Event eXperiment (DUNEX) site on Pea Island National Wildlife Refuge (PINWR) and at the Basnight Bridge (BB), NC. In November 2020, April, September, and October 2021, USGS and Woods Hole Oceanographic Institute (WHOI) scientists conducted multiple field surveys to collect the bathymetry as part of a topobathy time series. DUNEX is a multi-agency, academic, and non-governmental organization collaborative community experiment designed to study nearshore coastal processes during storm events. USGS participation in DUNEX will contribute new measurements and models that will increase our understanding of storm impacts to coastal environments, including hazards to humans and infrastructure and changes in landscape and natural habitats. Collected data are part of field activity 2021-029-FA and donated data 2020-024-DD and are related to field activity 2021-028-FA and 2021-032-FA.
Supplemental_Information:
Bathymetry in this section is single-beam sounding data and trackline, the interpolated single-beam echosounder products are merged with topography data in the larger ‘Topobathy’ section of the release. For more information about the data, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2020-024-DD and https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-029-FA. Bounding coordinates represent the maximum bounds of the tracklines provided in this dataset.
  1. How might this data set be cited?
    Traykovski, Peter A., 20220607, Single-beam bathymetric data in Pea Island National Wildlife Refuge, North Carolina in November 2020 and April, September, and October 2021: data release DOI:10.5066/P9DPZZG2, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Over, Jin-Si R., Sherwood, Christopher R., Traykovski, Peter A., Brosnahan, Sandra M., Olson, Alex J., and Randall, Noa R., 2022, DUNEX topographic, bathymetric, and supporting GPS data collected in Pea Island National Wildlife Refuge, North Carolina 2020-2021: data release DOI:10.5066/P9DPZZG2, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Over, J.R., Sherwood, C.R., Traykovski, P.A., Olson, A.J., Randall, N.R., and Brosnahan, S.M., 2022, DUNEX topographic, bathymetric, and supporting GPS data collected in Pea Island National Wildlife Refuge, North Carolina 2020-2021: U.S Geological Survey data release, https://doi.org/10.5066/P9DPZZG2.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.52596778
    East_Bounding_Coordinate: -75.45868561
    North_Bounding_Coordinate: 35.76587870
    South_Bounding_Coordinate: 35.67294873
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/623dcbc6d34e915b67d6552f?name=PINWR_ASV_browse.jpg&allowOpen=true (JPEG)
    Image of the SSV used to collect single-beam bathymetry data.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 22-Nov-2020
    Currentness_Reference:
    Ground condition; data collected on multiple days but some surveys have been combined into one grid: 20201122 and 20201127; 20210419 and 20210420; 20211019 and 20211020.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: 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.
    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: -69.000000
      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
      Ordinates (y-coordinates) are specified to the nearest 1
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983 (National Spatial Reference System 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:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    PINWR_Bathymetry_singlebeam_tracklines.zip
    Zip file contains ten CSV files of the post-processed navigation GNSS trackline data for the single-beam echosounders used in Pea Island National Wildlife Refuge. Following attributes are reported as if all CSV files were one. (Source: U.S. Geological Survey, Coastal and Marine Hazards and Resources Program)
    INFO
    USGS Number of Field Activity or Donated Data (Source: USGS) Character string.
    Equipment
    Remote vehicle used: Small Surf Vehicle (SSV), Yellowfin, or Needle Nose (Source: USGS) Character string.
    Date
    Date measurements were taken, in YYYYMMDD (Source: USGS) Character string.
    Time_UTC
    Time position values were taken in the format hh:mm:ss Zulu Time (UTC) (Source: USGS) Character string.
    Latitude
    Post-processed kinematic (PPK) latitude of GNSS antenna position at the moment of a valid sounding value relative to the NAD83(2011). (Source: USGS)
    Range of values
    Minimum:35.67294873
    Maximum:35.76587870
    Units:Decimal degrees
    Longitude
    Post-processed kinematic (PPK) longitude of GNSS antenna position at the moment of a valid sounding value relative to the NAD83(2011). (Source: USGS)
    Range of values
    Minimum:-75.52596778
    Maximum:-75.45868561
    Units:Decimal degrees
    Easting
    Post-processed kinematic (PPK) X-coordinates in NAD83(2011)/UTM Zone 18N interpolated from valid echo-sounder altitude samples. (Source: USGS)
    Range of values
    Minimum:452455.309
    Maximum:458493.229
    Units:meters
    Northing
    Post-processed kinematic (PPK) Y-coordinates in NAD83(2011)/UTM Zone 18N interpolated from valid echo-sounder altitude samples. (Source: USGS)
    Range of values
    Minimum:3947779.589
    Maximum:3958108.589
    Units:meters
    Echo_range
    The range to the seafloor from the echosounder (Source: producer-defined)
    ValueDefinition
    NaNNo data
    Range of values
    Minimum:-20.558
    Maximum:0.000
    Units:meters
    GPS_z
    Post-processed kinematic (PPK) position (Z-coordinates) of the GNSS receiver in reference to NAVD88 in meters on the electric autonomous survey vehicle. (Source: USGS)
    Range of values
    Minimum:-0.687
    Maximum:1.696
    Units:meters
    Seafloor_depth
    Depth refers to the elevation of the seafloor in NAVD88 in meters and is calculated by subtracting the Antenna_Z_offset (0.43 meters for the SSV and 0.25 for Yellowfin) and adding the Echo_range and GPS_z. (Source: producer-defined)
    ValueDefinition
    NaNNo data
    Range of values
    Minimum:-21.321
    Maximum:0.926
    Units:meters
    Entity_and_Attribute_Overview:
    The single-beam trackline and GPS data used to create the bathymetric part of grids in the Topobathy section of the larger citation are all provided in the zip folder PINWR_bathymetry_tracklines.zip as CSVs named with the USGS field ID, location on Pea Island National Wildlife Refuge (PINWR) as either the DUNEX site or Basnight Bridge (BB), Bathymetry_trackline, and the date collected in MMDD.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2021-029-FA and Donated Data 2020-024-DD

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Peter A. Traykovski
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Jin-Si R. Over
    U.S. Geological Survey, Northeast Region: Woods Hole Coastal and Marine Science Center
    U.S. Geological Survey
    Woods Hole, MA

    508-548-8700 x2269 (voice)
    jover@usgs.gov

Why was the data set created?

Single-beam trackline dataset is for mapping the elevation of the nearshore and can be used to create bathymetric products that can be merged with the topographic data in the larger citation.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2022 (process 1 of 1)
    The single-beam bathymetry data were collected by launching the remote vehicle. Two were used to collect single-beam data, the small surf vehicle (SSV) had an EA24 dual frequency (250/400 kHz) echosounder and the Yellowfin had a Cerulean s500 echosounder. The vehicles were controlled near the shore by Peter Traykovski and put on auto-pilot using predetermined tracklines for longer transects offshore. The raw bathymetry data was processed with the following steps 1. Binary data was parsed (BU353s4 GPS Puck, Time, Position and Echosounder range) into MATLAB (v. 2020b) from the EA24 and s500 echosounders using MATLAB Scripts developed by Peter Traykovski at WHOI - see contact below 2. Post Processed Kinematic (PPK) GNSS (Novatel OEM-V2_L1L2) data from the vessel were corrected using the base station (Java Triumph-1) data in Novatel Inertial Explorer (Version 8.70.8722) using the datum NAD83(2011) and then the vertical datum NAVD88 GEOID 12B. A projection for UTM Zone 18N was also specified to get the Easting and Northing information. 3. Refined time alignment to account for any small time delays between GPS data and echosounder data collection. This is accomplished using the time lagged cross correlation of echosounder range and PPK GNSS altitude in locations with a relatively flat bottom. The resulting time shift was 18 seconds. The GPS measures vertical fluctuation of the boat due to waves and these fluctuations are also visible in echosounder data. The equation in Step 5 removes the vertical fluctuation due to waves from the echosounder data leaving only true bathymetry if GPS and the echosounder are well synced. The lagged cross correlation processing ensures they are synced optimally. 4. GPS values (GPS_z) were interpolated to time of echosounder samples collected at 450kHz with the MATLAB function interp1 (linear interpolation) and the 'pchip' parameter selected. 5. Seafloor elevation (referred to as seafloor_depth) was calculated with reference to the NAVD88 datum in meters using the following equation: Seafloor_depth = GPS_z + Echo_range – Antenna_Z_offset; the offset of the GNSS antenna to the echosounder transducer on the z-axis of the ASV is 0.43 m for the EA24 and 0.25 m for the Cerulean s500. 7. See the Topobathy products in the larger citation for the processing steps to create GeoTIFF grids from the trackline data. Person who carried out this activity:
    Peter A. Traykovski
    Woods Hole Oceanographic Institution
    Associate Scientist
    226 Woods Hole Rd, MS #12
    Woods Hole, MA

    508-289-2638 (voice)
    ptraykovski@whoi.edu
  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?
    No official QC test was performed, but all depth values are internally consistent in relation to each other and are comparable to values of published bathymetry in the area (e.g. 2022 USGS CoNED Topobathy DEM (1851 - 2020): Coastal Carolinas, available at https://www.fisheries.noaa.gov/inport/item/67013).
  2. How accurate are the geographic locations?
    Navigation information was acquired from the GNSS receiver in PPK mode with a Multi-band GNSS antenna that has a theoretical horizontal accuracy of 1-5 cm and average reported SD of 1.0 cm.
  3. How accurate are the heights or depths?
    The vertical navigational information was acquired from the GNSS receiver in PPK mode with a Multi-band GNSS antenna and hot shoe adapter with a theoretical horizontal accuracy of 1-5 cm and average reported SD of 1.6 cm. The navigational accuracies do not represent the accuracy of the derived bathymetric soundings. The vertical accuracy of the raw data in water depths of 10 meters or less, based on industry standard system specifications for 450 and 500 kHz transmit frequencies, is 5-10 centimeters.
  4. Where are the gaps in the data? What is missing?
    All collected survey line data were edited for erroneous soundings before being incorporated into the final topobathy grids in the larger citation. Beginning and end null values were removed from the raw trackline data but NaNs are still within the data.
  5. How consistent are the relationships among the observations, including topology?
    The tracklines in the CSV files represent single-beam echo-sounder bathymetry data collected by Peter Traykovski (WHOI). These data were combined with post-processed kinematic (PPK) orthometric heights collected using a GNSS receiver (EMLID Reach M2) mounted on self-righting remote vehicles corrected to a base station (JAVAD Triumph) onshore in GEOID12B NAVD88 meters. The GNSS antenna offset from the echo-sounder is taken into account when calculating the seafloor depth; see Processing Steps.

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 redistributable with proper metadata and source attribution. Although these data have been processed successfully on a computer system at 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. 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. Not for navigational use. Please recognize the U.S. Geological Survey (USGS) as the source of this information. Not for navigational use.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888- 275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? Each file in the zip folder represents a separate collection of single-beam trackline and GPS data from Pea Island National Wildlife Refuge.
  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 U.S. Geological Survey 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?
    These data are available as a zip folder with CSV files. To utilize these data, the user must have a way to unzip the raw data and read a CSV.

Who wrote the metadata?

Dates:
Last modified: 07-Jun-2022
Metadata author:
Jin-Si R. Over
U.S. Geological Survey
Geographer
U.S. Geological Survey
Woods Hole, MA

508-548-8700 x2269 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS.
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9DPZZG2/DUNEX_PINWR_singlebeam_metadata.faq.html>
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