Coastal Multibeam Bathymetry Data Collected in August 2019 from Cedar Island, Virginia

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Frequently anticipated questions:

What does this data set describe?

Title:
Coastal Multibeam Bathymetry Data Collected in August 2019 from Cedar Island, Virginia
Abstract:
An Ellipsoidally Referenced Survey (ERS) using two Teledyne Reson SeaBat T50-P multibeam echosounders, in dual-head configuration, was conducted by the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC), covering the nearshore, seaward of Cedar Island, Virginia, from August 14-21, 2019. This dataset, Cedar_ Island_2019_MBES_xyz.zip, includes the processed elevation point data (x,y,z), as derived from a 1-meter (m) bathymetric grid. Additionally, the dataset Cedar_Island_2019_MBES_Backscatter.zip includes the acoustic backscatter intensity data in 32-bit float GeoTIFF (.tif) format.
Supplemental_Information:
The processed sonar data are provided as American Standard Code for Information Interchange (ASCII) x,y,z point data files, and 32-bit float GeoTIFF raster format. These values are not the individual soundings, but nodes from a 1-m bathymetric grid. The Z value for the node is generated by utilizing a Combined Uncertainty and Bathymetry Estimator (CUBE) surface and has an estimated total value of uncertainty (Calder and Wells, 2007). The bathymetry data were collected and processed in the World Geodetic System of 1984 (WGS84[G1762]) vertical and horizontal datums and were subsequently transformed using the National Oceanic and Atmospheric Administration's (NOAA) VDatum version 4.1 transformation software (https://vdatum.noaa.gov/) horizontally into the North American Datum of 1983 (NAD83 [2011]) and vertically into the North American Vertical Datum of 1988 (NAVD88) relative to the GEOID model of 2012B (GEOID12B).
  1. How might this data set be cited?
    Stalk, Chelsea A., Farmer, Andrew S., Miselis, Jennifer L., and Fredericks, Jake J., 20201005, Coastal Multibeam Bathymetry Data Collected in August 2019 from Cedar Island, Virginia: U.S. Geological Survey Data Release doi:10.5066/P927Q8M1, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.61276870
    East_Bounding_Coordinate: -75.54333882
    North_Bounding_Coordinate: 37.69364052
    South_Bounding_Coordinate: 37.57601867
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 14-Aug-2019
    Ending_Date: 21-Aug-2019
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (44502505)
    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: -75.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.6096
      Ordinates (y-coordinates) are specified to the nearest 0.6096
      Planar coordinates are specified in meters
      The horizontal datum used is World Geodetic System of 1984.
      The ellipsoid used is WGS_84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: World Geodetic System of 1984
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    2019_332_Cedar_Island_MBES_1m_WGS84_UTM18N.xyz
    ASCII text (.xyz) file containing the processed 1-m bathymetric grid x,y,z data in the WGS84 [G1762] realization (ellipsoid height). (Source: HYPACK)
    WGS84_UTM18N_X
    WGS84 UTM Zone 18N X-coordinate (easting) of sample point, in meters. (Source: HYPACK)
    Range of values
    Minimum:445977.000
    Maximum:452023.000
    Resolution:0.001
    WGS84_UTM18N_Y
    WGS84 UTM Zone 18N Y-coordinate (northing) of sample point, in meters. (Source: HYPACK)
    Range of values
    Minimum:4158951.000
    Maximum:4171964.000
    Resolution:0.01
    WGS84_Z
    WGS84 (ellipsoid height) of sample point, in meters. (Source: HYPACK)
    Range of values
    Minimum:-68.580
    Maximum:-39.396
    Resolution:0.001
    TPU
    TPU = Total Propagated Uncertainty, in meters (Source: CARIS)
    Range of values
    Minimum:0.055
    Maximum:0.263
    Resolution:0.001
    2019_332_Cedar_Island_MBES_1m_NAD83_UTM18N_NAVD88_G12B.xyz
    ASCII text (.xyz) file containing the processed 1-m bathymetric grid x,y,z data in NAD83 [2011], NAVD88, which were derived using the GEOID12B model (orthometric height). (Source: HYPACK; VDatum)
    NAD83_UTM18N_X
    NAD83 UTM Zone 18N X-coordinate (easting) of sample point, in meters. (Source: HYPACK; VDatum)
    Range of values
    Minimum:445977.499
    Maximum:452023.498
    Resolution:0.001
    NAD83_UTM18N_Y
    NAD83 UTM Zone 18N Y-coordinate (northing) of sample point, in meters. (Source: HYPACK; VDatum)
    Range of values
    Minimum:4158950.034
    Maximum:4171963.032
    Resolution:0.001
    NAVD88_GEOID12B_Z
    NAVD88 (orthometric height) of sample point, in meters, with respect to GEOID12B. (Source: HYPACK; VDatum)
    Range of values
    Minimum:-30.450
    Maximum:-1.337
    Resolution:0.001
    TPU_WGS84
    TPU = Total Propagated Uncertainty, in meters, as reported for WGS84 data. A static uncertainty value of 7.6158 cm is associated with the transformation of this data. (Source: CARIS)
    Range of values
    Minimum:0.055
    Maximum:0.263
    Resolution:0.001

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Chelsea A. Stalk
    • Andrew S. Farmer
    • Jennifer L. Miselis
    • Jake J. Fredericks
  2. Who also contributed to the data set?
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
  3. To whom should users address questions about the data?
    Chelsea A. Stalk
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    Electronics Technician (Marine Instrumentation)
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)502-8000 (voice)
    cstalk@usgs.gov

Why was the data set created?

The purpose of the survey was to collect high-density multibeam bathymetry data nearshore Cedar Island, VA to better evaluate shoreface morphology. Data were collected during USGS Field Activity Number (FAN) 2019-332-FA. Additional survey and data details are available from the USGS Coastal and Marine Geoscience Data System (CMGDS) at, https://cmgds.marine.usgs.gov/fan_info.php?fan=2019-332-FA.

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: 2019 (process 1 of 5)
    Acquisition: An ERS consisting of multibeam bathymetry and acoustic backscatter was conducted using two Teledyne Reson SeaBat T50-P multibeam echosounders, in dual-head configuration. The pair of Mills Cross [configuration] transmit and receive arrays, were placed 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 gunnel of the research vessel (R/V) Sallenger, a 26-foot fiberglass vessel. The sonar arrays were oriented athwartships (primary and secondary arrays facing outward and down to port and starboard, respectively) and located approximately 1-m below the waterline when deployed. An Applanix Pos MV Wavemaster II V5 inertially aided navigation system was used for timing, positioning, and attitude. The Inertial Measurement Unit (IMU) was mounted atop the sonar bracket just aft of the pole. Two Trimble GA830 Global Navigation Satellite System antennas were affixed atop the cabin approximately amidships of the vessel, two meters apart, port-starboard. An AML Oceanographic Micro-X sound velocity sensor was used for speed of sound readings at the sonar head. A Sontek CastAway CTD was used for measuring sound velocity profiles. Hydrographic survey acquisition and processing software, HYPACK/HYSWEEP (version 18.0.9.0) managed data inputs from sensors and produced two files (.RAW and .HSX). Data were collected in WGS84 [G1762] Universal Transverse Mercator (UTM) Zone 18 North (18N) coordinates. Person who carried out this activity:
    Chelsea Stalk
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)502-8000 (voice)
    cstalk@usgs.gov
    Date: 2019 (process 2 of 5)
    Processing: Positioning and attitude data were post-processed in Applanix POSPac MMS (POSPac) software version 8.4 Service Pack 3. Raw position files were imported into POSPac and processed with the IN-Fusion PP-RTX processing mode utilizing Trimble CenterPoint RTX technology; creating smoothed best estimate of trajectory (SBET) files and dynamic error files (SMRMSG) for each day of the survey. Bathymetric data were post-processed in CARIS Hydrographic Information Processing System and Sonar Information Processing System (HIPS/SIPS) software version 11.1.3. HYPACK acquisition files (.HSX) were first imported into CARIS and then post-processed navigation files (SBET and SMRMSG) were imported and applied. Additionally, GPS tide (GPS tidal corrections utilize GPS height information from real time survey observations to obtain an ellipsoid height) was computed and sound velocity profiles were applied. Roll calibration was also performed, as necessary. TPU was calculated from real time values recorded in the HSX and the SMRMSG files. Data were filtered to exclude any points with RESON Quality flags of 0, 1, and 2 (these flags are assigned to individual soundings at the time of acquisition and are a metric of pass/fail in regards to both brightness and collinearity: 0 = fail both, 1 = pass brightness only, 2 = pass collinearity only), as well as soundings that had a TPU greater than stated IHO Special Order standards (IHO, 2008). Refraction artifacts were addressed using Refraction Editor. Further editing was performed in Subset Editor. A visual and statistical inspection of the data was performed to serve as quality control. A 1-m bathymetric CUBE surface was computed and the final surface was exported as an x,y,z ASCII file using the Base Surface to ASCII function. Person who carried out this activity:
    Chelsea Stalk
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)502-8000 (voice)
    cstalk@usgs.gov
    Data sources produced in this process:
    • 2019_332_Cedar_Island_MBES_1m_WGS84_UTM18N.xyz
    Date: 2019 (process 3 of 5)
    Backscatter Mosaic Creation: Acoustic Intensity Backscatter data (.7k) were loaded in CARIS Hydrographic processing software HIPS/SIPS version 11.3.4 using the SIPS Backscatter tool. The final CUBE bathymetry surface serves as input for geometric corrections and average temperature and salinity data (derived from the Sontek CastAway CTD measurements taken during acquisition) are utilized by the program to calculate local absorption and transmission loss. These inputs, along with the following settings were entered into the tool, and then processing was initiated [Weighted Average = blending, image type = beam average, weighting = swath, and an Angle-Varying gain = 200]. During processing, the tool automatically creates a beam pattern file (.bbp), which is used to correct for variations in the beam pattern of the system. Upon completion, a 1–m backscatter mosaic with intensity values ranging from –79.1412 to 22.3882 was created. After visual inspection, the mosaic was exported as an 32-bit float GeoTIFF (.tif) using the surface to GeoTIFF function. Person who carried out this activity:
    Chelsea Stalk
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)502-8000 (voice)
    cstalk@usgs.gov
    Data sources produced in this process:
    • 2019_332_Cedar_Island_MBES_1m_Backscatter.tif
    Date: 2019 (process 4 of 5)
    Datum Transformation: Final x,y,z data were converted using NOAA's VDatum v.4.1 software conversion tool from the WGS84 [G1762] realization (ellipsoid height) to NAD83 [2011] and NAVD88, using the GEOID12B model (orthometric height). Person who carried out this activity:
    Chelsea Stalk
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)502-8000 (voice)
    cstalk@usgs.gov
    Data sources produced in this process:
    • 2019_332_Cedar_Island_MBES_1m_NAD83_UTM18N_NAVD88_G12B.xyz
    Date: 13-Oct-2020 (process 5 of 5)
    Added keywords section with USGS persistent identifier as theme keyword. 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?
    Forde, Arnell S., Stalk, Chelsea A., and Miselis, Jennifer L., 20200930, Archive of Chirp Subbottom Profile Data Collected in 2019 from Cedar Island, Virginia: U.S. Geological Survey Data Release doi:10.5066/P9S75Q0U, U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

    Online Links:

    Calder, B.R. and Wells, D.E., 20070129, CUBE User's Manual: University of New Hampshire, Center for Coastal and Ocean Mapping, Durham, NH.

    Online Links:

    Other_Citation_Details: pages 3-12
    Organization, International Hydrographic, 2008, IHO Standards for Hydrographic Surveys: International Hydrographic Bureau, 4, quai Antoine 1er B.P. 445 - MC 98011 MONACO Cedex Principauté de Monaco.

    Online Links:

    Other_Citation_Details: pages 15-16

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

  1. How well have the observations been checked?
    These datasets were from one research cruise and are therefore internally consistent. Methods were employed to maintain data collection consistency aboard the platform. During mobilization, each piece of equipment was isolated to obtain internal and external offset measurements with respect to the survey platform. All the critical measurements were recorded manually and digitally entered into their respective programs.
  2. How accurate are the geographic locations?
    All data were collected and processed to meet or exceed International Hydrographic Organization (IHO) Special Order standards for positioning and depth (IHO, 2008). Individual Total Propagated Uncertainty (TPU) values associated with each node are available in the x,y,z file.
  3. How accurate are the heights or depths?
    All data were collected and processed to meet or exceed IHO Special Order standards for positioning and depth (IHO, 2008). Individual TPU values associated with each node are available in the XYZ file. Transformed data have an additional reported vertical transformation error of 7.6158 centimeters (cm).
  4. Where are the gaps in the data? What is missing?
    These are complete post-processed x,y,z bathymetric data points and an associated 1-m backscatter mosaic from multibeam bathymetry and acoustic intensity data collected nearshore Cedar Island, Virginia, August 2019.
  5. How consistent are the relationships among the observations, including topology?
    These file represents the post-processed bathymetric data (x,y,z) and acoustic intensity (.tif) collected during a multibeam bathymetry survey.

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. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    Chelsea Stalk
    U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
    600 4th Street South
    St. Petersburg, FL
    USA

    (727)502-8000 (voice)
    cstalk@usgs.gov
  2. What's the catalog number I need to order this data set? 2019_332_Cedar_Island_MBES_1m_WGS84_UTM18N.xyz, 2019_332_Cedar_Island_MBES_1m_NAD83_UTM18N_NAVD88_G12B.xyz, 2019_332_Cedar_Island_MBES_1m_Backscatter.tif
  3. What legal disclaimers am I supposed to read?
    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 on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS shall not be held liable for improper or incorrect use of the data described 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?

Who wrote the metadata?

Dates:
Last modified: 23-Sep-2021
Metadata author:
Chelsea Stalk
U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center
600 4th Street South
St. Petersburg, FL
USA

(727)502-8000 (voice)
cstalk@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/Cedar_Island_2019_MBES_metadata.faq.html>
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