Coastal Single-beam Bathymetry Data Collected in August 2018 from the Chandeleur Islands, Louisiana

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:

What does this data set describe?

Title:
Coastal Single-beam Bathymetry Data Collected in August 2018 from the Chandeleur Islands, Louisiana
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 the northern Chandeleur Islands, August 17-21, 2018. During this study, bathymetry data were collected aboard the research vessel (R/V) Jabba Jaw, a 21-foot (ft) twin hulled vessel 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. This dataset, Chandeleur_2018_SBB_xyz.zip, was transformed from the initial World Geodetic System of 1984 (WGS84) G1762 datum to the North American Datum of 1983 (NAD83) North American Vertical Datum of 1988 (NAVD88), using the GEOID09 model (National Oceanic and Atmospheric Administration (NOAA) National Geodedic Survey (NGS) Transformation software VDatum, version 3.9 - http://vdatum.noaa.gov/).
  1. How might this data set be cited?
    Stalk, Chelsea A., Miselis, Jennifer L., DeWitt, Nancy T., and Reynolds, Billy J., 20200215, Coastal Single-beam Bathymetry Data Collected in August 2018 from the Chandeleur Islands, Louisiana: U.S. Geological Survey Data Release doi:10.5066/P9E6E79E, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -88.916490
    East_Bounding_Coordinate: -88.761330
    North_Bounding_Coordinate: 30.070269
    South_Bounding_Coordinate: 29.867649
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 17-Aug-2018
    Ending_Date: 21-Aug-2018
    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 (687,423)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 16
      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?
    Chandeleur_Islands_2018_SBB_WGS84_xyz.txt
    Comma-delimited xyz file and Esri shapefile containing location, elevation, and date information pertaining to data collected aboard the RV Jabba Jaw in 2018, nearshore the Chandeleur Islands, Louisiana. (Source: U.S. Geological Survey)
    WGS84_X
    WGS84 UTM x-axis coordinate (Zone 16N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:315268.074
    Maximum:329888.846
    Units:meters
    WGS84_Y
    WGS84 UTM y-axis coordinate (Zone 16N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:3305655.75
    Maximum:3327884.757
    Units:meters
    Ellipsoid
    Z-value (elevation) in WGS84 ellipsoid heights (Source: U.S. Geological Survey)
    Range of values
    Minimum:-41.599
    Maximum:-28.078
    Units:meters
    Year
    Calendar year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:2018
    Maximum:2018
    Units:meters
    DOY
    Day of year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:229
    Maximum:233
    Time
    UTC time of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:15:57:45.039
    Maximum:22:05:33.578
    Hypack_Line
    ub-FAN identifier followed by platform name abbreviation, line number and start of line UTC time. (Source: HYPACK/U.S. Geological Survey) N/A
    Depth_TPU
    Total propagated uncertainty value as calculated by CARIS software, in meters. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.125
    Maximum:5.387
    Chandeleur_Islands_2018_SBB_NAD83_NAVD88_G09.txt
    Comma-delimited xyz file containing location, elevation, and date information. (Source: U.S. Geological Survey)
    NAD83_X
    NAD83 UTM x-axis coordinate (Zone 16N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:315268.86299
    Maximum:329889.63131
    Units:meters
    NAD83_Y
    NAD83 UTM y-axis coordinate (Zone 16N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:3305655.13157
    Maximum:3327884.1338
    Units:meters
    NAVD88_G09
    Z-value (elevation) in NAVD88 GEOID 09 (Source: U.S. Geological Survey)
    Range of values
    Minimum:-13.66214
    Maximum:-0.50582
    Units:meters
    Year
    Calendar year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:2018
    Maximum:2018
    Units:meters
    DOY
    Day of year of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:229
    Maximum:233
    UTC_Time
    UTC time of data acquisition (Source: U.S. Geological Survey)
    Range of values
    Minimum:15:57:45.039
    Maximum:22:05:33.578
    Hypack_Line
    Sub-FAN identifier followed by platform name abbreviation, line number and start of line UTC time. (Source: HYPACK/U.S. Geological Survey) N/A
    Depth_TPU
    Total Propagated uncertainty value as calculated by CARIS software measures in meters. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.130
    Maximum:5.387

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
    • Jennifer L. Miselis
    • Nancy T. DeWitt
    • Billy J. Reynolds
  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. The authors would like to thank Andrew Farmer 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
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Researcher III
    600 4th St. S
    St. Petersburg, FL
    USA

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

Why was the data set created?

To determine continued change to the shoreface morphology and evolution at the Chandeleur Islands, Louisiana, scientists from the USGS SPCMSC conducted a bathymetric survey of the Chandeleur Islands, during Field Activity Number (FAN) 2018-350-FA, sub FAN 18BIM02. This dataset, Chandeleur_2018_SBB_xyz.zip consists of single-beam horizontal position and vertical elevation data collected within the nearshore zone of the Chandeleur Islands, aboard a single research vessel. Additional survey and data details are available from CMGDS at, https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-350-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: 2018 (process 1 of 7)
    GPS Acquisition: One Geographic Positioning System (GPS) base station was established on USGS benchmark MRK3, located within the northern portion of the Chandeleur Islands. 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: Billy J. Reynolds
    Engineering Technician
    600 4th St. S
    St. Petersburg, FL
    USA

    727-502-8067 (voice)
    727-502-8181 (FAX)
    breynolds@usgs.gov
    Date: 2018 (process 2 of 7)
    Single-Beam Bathymetry Acquisition: The single-beam bathymetric data were collected under USGS FAN 2018-350-FA and encompasses data from a single survey platform, the RV Jabba Jaw, a 21 ft shallow draft center console catamaran (18BIM02), which surveyed a total of 143.726 line-km (66 lines). Boat motion was recorded at 50-millisecond (ms) intervals using a TSS 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. Depth soundings were recorded at 50-ms intervals using an Odom echotrac CV100 sounder with a 200-kilohertz (kHz) transducer. Data from the GPS receiver, motion sensor, and fathometer were recorded in real-time aboard the vessel independently 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 44 successful sound velocity casts were taken throughout the survey at an average depth of 4.47 m, and on average produced a sound velocity of 1537.12 meters per second (m/s). Person who carried out this activity:
    Chelsea A. Stalk
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Researcher III
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@contractor.usgs.gov
    Date: 2018 (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 vessels 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. Concurrent post-processed navigation data to single-beam data points replace the uncorrected rover positions, recorded during acquisition, in subsequent processing steps. The GPS data were processed and exported in the WGS84 (G1762) geodetic datum. Person who carried out this activity:
    Chelsea A. Stalk
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Researcher III
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@contractor.usgs.gov
    Date: 2018 (process 4 of 7)
    All data were processed using CARIS HIPS and SIPS (Hydrographic Information Processing System and Sonar Information Processing System) version 11.0.7. The raw HYPACK data files were imported into CARIS, the differentially corrected navigation files were imported using the generic data parser tool, and any SVP profile casts were entered and edited using the SVP editor. The bathymetric data components (position, motion, depth, and SOS) were then merged and geometrically corrected in CARIS to produce processed xyz data. TSS Motion Reference Unit (MRU) malfunction on Day 229 was corrected by applying a 90-degree offset to all effected data. Data associated with the correction are computed to have unreasonably high TPU values due to the applied offset. 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 xyz ASCII text file referenced to WGS84 (G1762), ellipsoid height in meters. Person who carried out this activity:
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher III
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@contractor.usgs.gov
    Date: 2018 (process 5 of 7)
    Quality Control, Quality Assurance (QA/QC) and Uncertainty Analysis: All single-beam data exported from CARIS, and elevation data exported from GrafNav were imported into Esri ArcMap version 10.6.0, where a shapefile of the individual sounding data points (xyz) 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 trackline shapefile was produced using X-tools Pro "Make Polylines from Points" function for each survey platform. Utilizing both the xyz (point) and trackline (polyline) shapefiles, a Python script evaluated elevation differences at the intersection of crossing tracklines 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 trackline it previously surveyed was 11.79 cm. Since the bias between elevations was on the order of the Odom CV100 instrument accuracy (1 cm +/- 0.7 percent depth), no adjustments were made. These merged files were exported from Esri ArcMap as an xyz text (.txt) file and made available in the download section of this data release, along with the populated trackline shapefiles. Person who carried out this activity:
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher III
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@contractor.usgs.gov
    Data sources used in this process:
    • 18BIM02_SBB_Level_03_P9E6E79_WGS84_UTM16N.txt
    Data sources produced in this process:
    • Chandeleur_Islands_2018_SBB_WGS84_xyz.txt Chandeleur_Islands_2018_SBB_WGS84_Tracklines.shp
    Date: 2018 (process 6 of 7)
    Datum Transformation: NOAA's VDatum v.3.9 was used to transform single-beam and GPS elevation data points (xyz) from their data acquisition datum (WGS84 G1762) to the NAD83 reference frame with NAVD88 elevations using the NGS geoid model of 2009 (GEOID09). For conversion from the WGS84 ellipsoid to NAVD88, there is a total of 7.616 cm of uncertainty in the transformation (http://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:
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Attn: Chelsea A. Stalk
    Researcher III
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@contractor.usgs.gov
    Data sources used in this process:
    • Chandeleur_Islands_2018_SBB_WGS84_xyz.txt
    Data sources produced in this process:
    • Chandeleur_Islands_2018_SBB_NAD83_NAVD88_G09.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?

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 field 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 Ashtech antenna reference point (ARP) were measured and accounted for in post-processing. Differential Global Positioning System (DGPS) coordinates were obtained through post-processing using specific software packages (NGS Online Positioning User Service (OPUS), and Waypoint Product Group GrafNav, version 8.7).
  2. How accurate are the geographic locations?
    All static base station sessions were processed through the OPUS maintained by the NOAA and the NGS. 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 USGS benchmark MRK3 was calculated and used in subsequent processing steps. Accuracy pertaining to the base station coordinates utilized are as follows: Horizontal = +/- 0.00017 seconds (s).
  3. How accurate are the heights or depths?
    All static base station sessions were processed through OPUS maintained by NOAA and NGS. 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 USGS benchmark MRK3 was calculated and used in subsequent processing steps (accuracy is computed to be +/- 0.0098 meters [m]). The kinematic (rover) trajectories were processed using GrafNav version 8.70 software by Novatel, Inc. In addition, total propagated uncertainty (TPU) values accompany each xyz data point and are a result of calculations performed in hydrographic processing software CARIS (Version 11.0.7). 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 horizontal position and vertical elevation x,y,z single-beam data from August 2018, collected within nearshore waters of the Chandeleur Islands, Louisiana. 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
    Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
    Researcher III
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    cstalk@contractor.usgs.gov
  2. What's the catalog number I need to order this data set? Chandeleur_Islands_2018_SBB_WGS84_xyz.txt, Chandeleur_Islands_2018_SBB_NAD83_NAVD88_G09.txt, Chandeleur_Islands_2018_SBB_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
Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
Researcher III
600 4th Street South
St. Petersburg, FL
USA

(727) 502-8000 (voice)
cstalk@contractor.usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/Chandeleur_Islands_2018_SBB_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:41 2021