1-Meter Sample Resolution Interferometric Swath Backscatter Data Collected in 2012 from the Chandeleur Islands, Louisiana (U.S. Geological Survey Field Activity Number 12BIM03)

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

Frequently anticipated questions:

What does this data set describe?

Title:
1-Meter Sample Resolution Interferometric Swath Backscatter Data Collected in 2012 from the Chandeleur Islands, Louisiana (U.S. Geological Survey Field Activity Number 12BIM03)
Abstract:
As part of the Barrier Island Evolution Research Project, scientists from the U.S. Geological Survey's St. Petersburg Coastal and Marine Science Center conducted nearshore geophysical surveys off the northern Chandeleur Islands, Louisiana, in June of 2012. The overall objective of the study is to better understand barrier-island geomorphic evolution, particularly storm-related depositional and erosional processes that shape the islands over annual to interannual timescales (1-5 years). The collection of geophysical data will allow us to identify relationships between the geologic history of the island and its present day morphology and sediment distribution. This mapping effort was the first in a series of three planned surveys in this area. High resolution geophysical data collected in each of 3 consecutive years along this rapidly changing barrier-island system will provide a unique time-series dataset that will significantly further the analyses and geomorphological interpretations of this and other coastal systems, improving our understanding of coastal response and evolution over short time scales (1-5 years). This report serves as an archive of processed interferometric swath and single-beam bathymetry data that were collected during two cruises (USGS Field Activity Numbers 12BIM03 and 12BIM04) along the northern portion of the Chandeleur Islands, Breton National Wildlife Refuge, Louisiana in July of 2012. Geographic information system data products include a 50 m-cell-size interpolated bathymetry grid surface, trackline maps, and point data files. Additional files include error analysis maps, Field Activity Collection System logs, and formal Federal Geographic Data Committee metadata.
Supplemental_Information:
The swath bathymetry data were collected and processed in the ITRF2005 geodetic reference ellipsoid. There are two components to the raw swath file (*.SXR)bathymetry and backscatter. The backscatter component was processed by importing the *.SXR files into SonarWiz5® version 5.06, applying corrections and exporting a final 1 meter mosaic.
  1. How might this data set be cited?
    U.S. Geological Survey, 2014, 1-Meter Sample Resolution Interferometric Swath Backscatter Data Collected in 2012 from the Chandeleur Islands, Louisiana (U.S. Geological Survey Field Activity Number 12BIM03):.

    Online Links:

    This is part of the following larger work.

    DeWitt, Nancy T., Bernier, Julie C., Pfeiffer, William R., Miselis, Jennifer L., Flocks, James G., Reynolds, B.J., Wiese, Dana S., and Kelso, Kyle W., 2014, Coastal Bathymetry Data Collected in 2012 from the Chandeleur Islands, Louisiana: U.S. Geological Survey Data Series 847, U.S. Geological Survey, St. Petersburg, Florida.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -88.917567
    East_Bounding_Coordinate: -88.794042
    North_Bounding_Coordinate: 30.096374
    South_Bounding_Coordinate: 29.940108
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 12-Jul-2012
    Ending_Date: 04-Aug-2012
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Raster
  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 17136 x 11640, type Grid Cell
    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: 0.9996
      Longitude_of_Central_Meridian: -87.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      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 meter
      The horizontal datum used is D North American 1983.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: North American Vertical Datum 88 (NAVD88)
      Depth_Resolution: 0.1
      Depth_Distance_Units: meter
      Depth_Encoding_Method: Implicit coordinate
  7. How does the data set describe geographic features?

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
    U.S. Geological Survey, Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Nancy T. DeWitt
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

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

Why was the data set created?

This 1-meter by 1-meter cell size backscatter mosaic that was derived from the processed interferometric swath bathymetry data collected in July of 2012 around the northern Chandeleur Islands, Louisiana.

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: 2012 (process 1 of 4)
    Swath Bathymetry Acquisition: The interferometric swath bathymetry data were collected aboard the R/V SurveyCat using a SEA SWATHplus-m 234 kHz interferometric sonar system mounted on a sled attached to a rail system, fastened between the catamaran halls allowing the instrument to align directly below the GPS antennae to minimize geometry errors. Boat position and motion data were recorded in real-time using a CodaOctopus F190R wetpod inertial measurement unit (IMU) mounted underwater between the transducer heads to minimize lever arm geometry errors between the observed depths and vessel motion. Real-time corrected positions were acquired via the OmniSTAR HP (High-Precision differential global navigation satellite system) satellite constellation subscription. OmniSTAR HP position correction data and motion data from the IMU were integrated with interferometric soundings in the SWATHplus software package, with positional and calibration offsets pre-defined by a session file (.sxs), allowing for real-time- corrected depths. Prior to deployment, all equipment offsets were surveyed in dry dock with the use of a laser total station. During the survey all swath data were recorded in SEA raw data format (.sxr). A Valeport Mini Sound Velocity Sensor (SVS) was attached to the transducer mount and collected continuous speed of sound (SOS) measurements at the depth of the transducers. These values were directly read and incorporated into the SWATHplus acquisition software giving real-time speed of sound at the transducer while underway. In addition, a separate sound velocity profiler (Valeport miniSVP) was used to collect speed of sound profiles (water surface to seafloor) at intervals throughout the survey. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Nancy T. DeWitt
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    ndewitt@usgs.gov
    Date: 2012 (process 2 of 4)
    Interferometric Swath Bathymetry Acquisition and Processing: Position data recorded by the Coda-Octopus F190R IMU system were corrected in real time via the OmniSTAR HP differential navigation service. The IMU applied real-time motion corrections for heave, roll, and pitch to the vertical component of each position fix. The corrected positions were integrated with the observed bathymetric values to calculate a final position and ellipsoid height representing the elevation of the seafloor with respect to the geodetic reference frame ITRF2005 (ITRF05) across the swath range. The Systems Engineering and Assessment Ltd program SWATHplus serves as both an acquisition software and initial processing software. Preliminary roll calibration data were collected and processed using SWATHplus and Grid Processor software versions 3.7.17. Instrument offset and calibration values were input into the session file (.sxs). The raw data files (.sxr) were then collected and processed with the updated system configuration file, which contained roll calibration values, measured equipment offsets, acquisition parameters, navigation parameters, speed of sound (SOS) at sonar head, and the SVP cast data. Any acoustic filtering applied in SWATHplus was also written to the processed data file (.sxp). The initial datum for the swath and backscatter data was ITRF05, which is the real-time acquisition datum of OmniSTAR HP position and navigation data. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Nancy T. DeWitt
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    ndewitt@usgs.gov
    Data sources used in this process:
    • raw files *.sxr
    Data sources produced in this process:
    • processed files *.sxp
    Date: 2013 (process 3 of 4)
    Acoustic backscatter analysis: The same raw data files (.sxr) were imported into SonarWiz5® version 5.06, and bottom tracking was applied to define the first returns from the seafloor through the water column directly below the swath transducers. Once the seafloor was defined, sonar beam angle correction was applied to remove the water column from the data and minimize target shadows in the data. A comprehensive backscatter mosaic was created from the individual swath lines and was adjusted for contrast and brightness. The final mosaic was exported in GeoTIFF format and imported into the ArcGIS project where the histogram was adjusted to enhance the display of seafloor surface. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Nancy DeWitt
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    ndewitt@usgs.gov
    Data sources used in this process:
    • raw files *.sxr
    Data sources produced in this process:
    • GeoTIFF
    Date: 13-Oct-2020 (process 4 of 4)
    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 from one research cruise and is therefore internally consistent. Methods are employed to maintain data collection consistency aboard the platform. During mobilization, each piece of equipment is isolated to obtain internal and external offset measurements with respect to the survey platform. All the critical measurements are recorded manually and digitally entered into their respective programs. For the interferometric swath bathymetry, offsets between the sonar head and the differential geographic positioning system (DGPS) antennas were measured and entered into the CodaOctopus F190R internal setup program. The DGPS was provided through the OmniSTAR High Performance wide-area GPS service. DGPS is always implemented for navigational accuracy either during acquisition or as a post-processing step. These bathymetric data have not been independently verified for accuracy.
  2. How accurate are the geographic locations?
    The stated horizontal accuracy of the OmniSTAR HP navigation subscription used during swath bathymetry acquisition is reported by the service as +/-15 centimeters (cm) (95 percent of the time). The Coda Octopus F190R IMU, which integrates the OmniSTAR HP position with motion, measures vessel velocity (manufacturer's specified accuracy +/- 0.014 m/s), roll and pitch(+/- 0.025 degrees), heading (1 m baseline 0.1 degrees), and heave (5 percent of heave amplitude or 5 cm).
  3. How accurate are the heights or depths?
    The stated horizontal accuracy of the OmniSTAR HP navigation subscription used during swath bathymetry acquisition is reported by the service as +/-15 cm (95 percent of the time). The Coda Octopus F190R IMU, which integrates the OmniSTAR HP position with motion, measures vessel velocity (manufacturer's specified accuracy +/- 0.014 meters per second (m/s)), roll and pitch(+/- 0.025 degrees), heading (1 m baseline 0.1 degrees), and heave (5 percent of heave amplitude or 5 cm). The vertical accuracy for the SWATHplus-M system varies with depth and across track range. At 57 m it is accurate to 10 cm vertically.
  4. Where are the gaps in the data? What is missing?
    This is a TIFF file of the backscatter samples derived from acoustic interferometric swath data collected in July 2012 from around the northern Chandeleur Islands. The backscatter intensity value is displayed as a digital number from 0 to 71 and the mosaic is 1-meter resolution.
  5. How consistent are the relationships among the observations, including topology?
    This archive contains the post-processed interferometric swath backscatter data from a single research cruise in July, 2012. Refer to the online data series linkage for field logs, vessel platform descriptions, and other survey information.

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:
The U.S. Geological Survey requests that it be referenced as the originator of this dataset in any future products or research derived from these data. These data should not be used for navigational purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: Nancy T. DeWitt
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 502-8000 (voice)
    ndewitt@usgs.gov
  2. What's the catalog number I need to order this data set? Downloadable Data
  3. What legal disclaimers am I supposed to read?
    This DVD 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?
  5. What hardware or software do I need in order to use the data set?
    The raster contained in the .zip file is available as a GeoTIFF file. To utilize this data, the user must have a GIS software package capable of reading .tif format. The ASCII text files contained in the .zip archive can be accessed with any standard text file reader.

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
U.S. Geological Survey
Attn: Nancy DeWitt
Geologist
600 4th Street South
St. Petersburg, FL
USA

(727) 502-8000 (voice)
ndewitt@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/12BIM03_IFS_mosaic_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:29 2021