Coastal Single-beam 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 Single-beam Bathymetry Data Collected in August 2019 from Cedar Island, Virginia
Abstract:
Scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center (USGS - SPCMSC) in St. Petersburg, Florida, conducted a single-beam bathymetric survey of Cedar Island, Virginia, August 9-15, 2019. During this study, bathymetry data were collected aboard a towed seismic sled outfitted with a single-beam echosounder.
Supplemental_Information:
For the single-beam bathymetry data, the differential positioning was obtained through post-processing the base station data to the rover.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., and Miselis, Jennifer L., 20201005, Coastal Single-beam Bathymetry Data Collected in August 2019 from Cedar Island, Virginia: U.S. Geological Survey Data Release doi:10.5066/P927Q8M1, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.615794
    East_Bounding_Coordinate: -75.537897
    North_Bounding_Coordinate: 37.695914
    South_Bounding_Coordinate: 37.570155
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 09-Aug-2019
    Ending_Date: 15-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 (480,440)
    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 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_1984.
      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 1988
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    Cedar_Island_2019_SBES_WGS84_xyz.txt
    Comma-delimited x,y,z file containing location, elevation, and date information pertaining to data collected on a towed chirp seismic sled, nearshore Cedar Island, Virginia in 2019. (Source: U.S. Geological Survey)
    WGS84_UTM18N_X
    WGS84 UTM x-axis coordinate (Zone 18N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:445711.948
    Maximum:452499.796
    Units:meters
    WGS84_UTM18N_Y
    WGS84 UTM y-axis coordinate (Zone 18N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:4158302.116
    Maximum:4172213.517
    Units:meters
    Ellipsoid
    Z-value (elevation) in WGS84, ellipsoid height (Source: U.S. Geological Survey)
    Range of values
    Minimum:-51.666
    Maximum:-38.831
    Units:meters
    WGS84_Lat
    WGS84 y-axis coordinate (latitude) (Source: U.S. Geological Survey)
    Range of values
    Minimum:37.570393
    Maximum:37.695743
    Units:Decimal Degrees
    WGS84_Long
    WGS84 x-axis coordinate (longitude) (Source: U.S. Geological Survey)
    Range of values
    Minimum:-75.614966
    Maximum:-75.53876
    Units:Decimal Degrees
    Year
    Calendar year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:2019
    Maximum:2019
    DOY
    Day of year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:221
    Maximum:226
    UTC_Time
    UTC time of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:12:31:49.28
    Maximum:21:22:30.33
    Hypack_Line
    Line number and start of line UTC time. (Source: HYPACK/U.S. Geological Survey) N/A
    Cedar_Island_2019_SBES_NAD83_NAVD88_G12B_xyz.txt
    Comma-delimited x,y,z file containing location, elevation, and date information. (Source: U.S. Geological Survey)
    NAD83_UTM18N_X
    NAD83 UTM x-axis coordinate (Zone 18N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:445712.447
    Maximum:452500.294
    Units:meters
    NAD83_ UTM18N_Y
    NAD83 UTM y-axis coordinate (Zone 18N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:4158301.151
    Maximum:4172212.549
    Units:meters
    NAVD88_G12B
    Z-value (elevation) in NAVD88 GEOID12B, orthometric height (Source: U.S. Geological Survey)
    Range of values
    Minimum:-13.583
    Maximum:-0.772
    Units:meters
    NAD83_Lat
    NAD83 y-axis coordinate (latitude) (Source: U.S. Geological Survey)
    Range of values
    Minimum:37.570393
    Maximum:37.695734
    Units:Decimal Degrees
    NAD83_Long
    NAD83 x-axis coordinate (longitude) (Source: U.S. Geological Survey)
    Range of values
    Minimum:-75.61496
    Maximum:-75.53876
    Units:Decimal Degrees
    Year
    Calendar year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:2019
    Maximum:2019
    DOY
    Day of year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:221
    Maximum:226
    UTC_Time
    UTC time of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:12:31:49.28
    Maximum:21:22:30.33
    Hypack_Line
    Line number and start of line UTC time. (Source: HYPACK/U.S. Geological Survey) N/A

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
  2. Who also contributed to the data set?
    Funding and (or) support for this study were provided by the USGS Coastal and Marine Hazards and Resources Program, specifically the Costal Sediment Availability and Flux (CSAF) project. The authors would like to thank Nancy DeWitt and Arnell Forde of the USGS - St. Petersburg, Florida for their thoughtful peer reviews.
  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 Iinstrumentation)
    600 4th St. S
    St. Petersburg, FL
    USA

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

Why was the data set created?

To evaluate shoreface morphology and geology along Cedar Island, Virginia, scientists from the USGS - SPCMSC conducted a bathymetric survey of Cedar Island, VA during Field Activity Number (FAN) 2019-332-FA. The objectives of the data collection were to map shoreface geology and morphology in support of the Coastal Sediment Availability and Flux (CSAF) Project. This dataset, Cedar_Island_2019_SBES_xyz.zip consists of single-beam horizontal position (x,y) and vertical (z) elevation data collected within the nearshore zone of Cedar Island. Additional survey and data details are available from the 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 7)
    GPS Acquisition: One GPS base station was established on NGS benchmark AJ4587 (https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=AJ4587), located within Seaside Park at the corner of Main Street and Atlantic Avenue, Wachapreague, VA. The base station was continually occupied and equipped with an Ashtech Proflex 800 GPS receiver recording 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via Thales Choke-ring antennas, recording at a rate of 0.1 s. Person who carried out this activity:
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea Stalk
    Electronics Technician (Marine Instrumentation)
    600 4th St. S
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    cstalk@usgs.gov
    Date: 2019 (process 2 of 7)
    Single-Beam Bathymetry Acquisition: The single-beam bathymetric data were collected under USGS FAN 2019-332-FA and encompasses data from a single survey platform, a Chirp seismic sled, towed by the R/V Sallenger, a 26 ft fiberglass research vessel. A total of 299.075 line-km (62 lines) were surveyed. Boat motion was recorded at 50-millisecond (ms) intervals using an SBG motion sensor. HYPACK (version 18.1.8.0), a marine surveying, positioning, and navigation software package, managed the planned-transect information and provided real-time navigation, steering, correction, data quality, and instrumentation-status information to the boat operator aboard the R/V Sallenger. Depth soundings were recorded at 50-ms intervals using an Odom Echotrac CV100 echo sounder with a 200-kilohertz (kHz) 4-degree transducer. Data from the GPS receiver, motion sensor, and echo sounder were recorded in real-time and merged into a single raw data file (*.RAW) in HYPACK, with each device string referenced by a device identification code and time stamped to Coordinated Universal Time (UTC). Sound velocity profile (SVP) measurements were collected using a single SonTek Castaway conductivity, temperature, and depth (CTD) instrument. The instrument was periodically cast overboard to observe changes in water column speed of sound (SOS). A total of 26 successful sound velocity casts were taken throughout the survey at an average depth of 3.99 m, and on average produced a sound velocity of 1519.08 meters per second (m/s). Person who carried out this activity:
    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
    Date: 2019 (process 3 of 7)
    Differentially Corrected Navigation Processing: The coordinate value of the GPS base station is the time weighted average (TWA) of all current survey occupations. The base station coordinates were imported into GrafNav version 8.7 (Waypoint Product Group) and the kinematic GPS data from the survey platform were post-processed to the concurrent GPS session data at the base station. During processing, steps were taken to ensure that the trajectories between the base and the rover were clean, resulting in fixed positions. By analyzing the graphs, trajectory maps, and processing logs that GrafNav produces for each GPS session, GPS data from satellites flagged by the program as having poor health or satellite time segments that had cycle slips could be excluded, or the satellite elevation mask angle could be adjusted to improve the position solutions. The final differentially corrected, precise DGPS positions were computed at 0.1 s and exported in American Standard Code for Information Interchange (ASCII) text format. The GPS data were processed and exported in the WGS84 (G1762) geodetic datum. Person who carried out this activity:
    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
    Date: 2019 (process 4 of 7)
    All bathymetry data were processed using CARIS HIPS and SIPS (Hydrographic Information Processing System and Sonar Information Processing System) version 11.2.3. The raw HYPACK data files were imported into CARIS, the differentially corrected navigation files were imported using the generic data parser (GDP) tool, and any SVP profile casts were entered and edited using the SVP editor. Lines from survey day 222 (8/10/2019) utilized real-time navigation due to GPS errors associated with a system failure. To utilize real-time navigation, the GPS heights were extracted from the raw Hypack (.RAW) files utilizing the CARIS command Line GUI (Version 2.0.4), and then written into an ASCII text file, which could be read by the GDP. Once GPS heights were applied using the GDP, a smoothing (moving average) filter of 60 seconds and a threshold of 1 was applied to data. The bathymetric data components (position, motion, depth, and SOS) for all data were then merged and geometrically corrected in CARIS to produce processed x,y,z data. Next, the data were edited for outliers and then further reviewed in the Subset Editor utility for crossing status, and questionable data points or areas. The geometrically corrected point data were then exported as an x,y,z ASCII text file referenced to WGS84 (G1762) ellipsoid height, in meters. Person who carried out this activity:
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Electronics Technician (Marine Instrumentation)
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
    Date: 2019 (process 5 of 7)
    Quality Control, Quality Assurance (QA/QC): All single-beam data exported from CARIS were imported into Esri ArcMap version 10.6.0, where a shapefile of the individual sounding data points (x,y,z) was created and plotted in 0.25-m color coded intervals. First, all data were visually scanned for any obvious outliers or problems. Next, a track line shapefile was produced using X-tools Pro "Make Polylines from Points" function. Utilizing both the x,y,z (point) and track-line (polyline) shapefiles, an in house Python script evaluated elevation differences at the intersection of crossing track lines by calculating the elevation difference between points at each intersection using an inverse distance weighting equation with a search radius of 1 m. The root mean square error (RMSe) when crossing a track line it previously surveyed was 23.5 cm. Lines from survey day 222 (8/10/2019), which utilized real-time navigation, had crossing offsets that exceeded the published Odom CV100 instrument accuracy (1 cm +/- 0.7 percent depth) and therefore were statically (vertical) adjusted by the average crossing offset. The following vertical adjustments were made, Line 0048_1731: -0.3826 m, 0049_1709_0001: -0.4578 m, 0050_1648: -0.4182 m, 0004_1930: +0.2767 m and Line 0001_1425: -0.2764 m. Once these adjustments were made, the crossing program was run for a second time, which produced RMSe results of 19.86 cm crossing error, however 91% of all crossings are under 10 cm. The final adjusted file was exported from Esri ArcMap as an x,y,z text (.txt) file and made available in the download section of this data release, along with the populated track line shapefiles. Person who carried out this activity:
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Electronics Technician (Marine Instrumentation)
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
    Data sources used in this process:
    • 2019_332_CedarIsland_SBES_WGS84_UTM18N_Level_03_xyz.txt
    Data sources produced in this process:
    • Cedar_Island_2019_SBES_WGS84_xyz.txt Cedar_Island_2019_SBES_WGS84_Tracklines.shp
    Date: 2019 (process 6 of 7)
    Datum Transformation: NOAA's VDatum v.3.9 was used to transform single-beam data points (x,y,z) from their data acquisition datum (WGS84 [G1762]) to the NAD83 reference frame with NAVD88 elevations using the NGS geoid model 2012B (GEOID12B). For conversion from the WGS84 ellipsoid height to NAVD88 orthometric height, there is a total of 7.616 cm of uncertainty in the transformation (https://vdatum.noaa.gov/docs/est_uncertainties.html). Resultant data files have been made available in the downloads section of this data release. Person who carried out this activity:
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Electronics Technician (Marine Instrumentation)
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@usgs.gov
    Data sources used in this process:
    • Cedar_Island_2019_SBES_WGS84_xyz.txt
    Data sources produced in this process:
    • Cedar_Island_2019_SBES_NAD83_NAVD88_G12B_xyz.txt
    Date: 13-Oct-2020 (process 7 of 7)
    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:

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

  1. How well have the observations been checked?
    The accuracy of the data is determined during data collection. This dataset is derived from a single survey using similar equipment, set-ups, and staff; therefore, the dataset is internally consistent. Methods are employed to maintain data collection consistency aboard the platforms. 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 then digitally entered into their respective programs. Offsets between the single-beam transducers, motion reference units, and the global positioning system (GPS) antenna reference point (ARP) were measured and accounted for in post-processing. Differential Global Positioning System (DGPS) coordinates were obtained through post-processing using the software Online Positioning User Service (OPUS) maintained by the NOAA and the NGS , and Waypoint Product Group GrafNav, version 8.7.
  2. How accurate are the geographic locations?
    All static base station sessions were processed through OPUS. The OPUS solutions were entered into a spreadsheet to compute a final, time-weighted position (latitude, longitude, and ellipsoid height) for the utilized base station. The time-weighted position for NGS benchmark AJ4587 (https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=AJ4587) was calculated and used in subsequent processing steps. Accuracy pertaining to the base station coordinates utilized are as follows: Horizontal = +/- 0.00027 seconds (s) or approximately 0.003 meters (m).
  3. How accurate are the heights or depths?
    All static base station sessions were processed through OPUS. The OPUS solutions were entered into a spreadsheet to compute a final, time-weighted position (latitude, longitude, and ellipsoid height) for the utilized base station. The time-weighted position for NGS benchmark AJ4587 (https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=AJ4587) was calculated and used in subsequent processing steps (accuracy is computed to be +/- 0.006 m). The kinematic (rover) trajectories were processed using GrafNav version 8.70 software by Novatel, Inc. Due to GPS errors associated with a system failure at the time of acquisition, lines from survey day 222 (8/10/2019) utilized real-time navigation, and therefore during the quality control/quality assurance (QA/QC) processing step, some lines with known GPS issues were statically adjusted by the average crossing offset. The following lines have the associated vertical uncertainty, which should be considered before use (Line 0048_1731: -0.3826 m, 0049_1709_0001: -0.4578 m, 0050_1648: -0.4182 m, 0004_1930: +0.2767 m and Line 0001_1425: -0.2764 m). 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?
    This data release contains single-beam horizontal position (x,y) and vertical (z) elevation data from August 2019, collected within nearshore waters of Cedar Island, Virginia. Users are advised to read the complete metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    These datasets are from one field activity with consistent instrument calibrations.

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. These data should not be used for navigational purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    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
  2. What's the catalog number I need to order this data set? Cedar_Island_2019_SBES_WGS84_xyz.txt, Cedar_Island_2019_SBES_NAD83_NAVD88_G12B_xyz.txt, Cedar_Island_2019_SBES_WGS84_Tracklines.shp
  3. What legal disclaimers am I supposed to read?
    This digital publication was prepared by an agency of the United States Government. Although these data were processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
Chelsea A. Stalk
U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
Electronics Technician (Maine Instrumentation)
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_SBES_metadata.faq.html>
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