Coastal Bathymetry Data Collected in 2016 from the Chandeleur Islands, Louisiana–Interferometric Bathymetry Soundings (XYZ)

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Farmer, Andrew S., Fredericks, Jake J., Miselis, Jennifer L., Buster, Noreen A., DeWitt, Nancy T., Kelso, Kyle W., Stalk, Chelsea A., and Reynolds, B.J., 20181115, Coastal Bathymetry Data Collected in 2016 from the Chandeleur Islands, Louisiana–Interferometric Bathymetry Soundings (XYZ): U.S. Geological Survey Data Release doi:10.5066/P993MBJK, U.S. Geological Survey, St. Petersburg, FL.

   Online Links:

   • https://doi.org/10.5066/P993MBJK

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -88.878361
   East_Bounding_Coordinate: -88.833079
   North_Bounding_Coordinate: 30.072475
   South_Bounding_Coordinate: 30.014710
   

3. What does it look like?
4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 10-Jun-2016

   Ending_Date: 19-Jun-2016

   Currentness_Reference:

   ground condition

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: tabular and vector digital data
   

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.
   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: -87.000000
      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 5.000000
      Ordinates (y-coordinates) are specified to the nearest 5.000000
      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 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      

      Vertical_Coordinate_System_Definition:

      Altitude_System_Definition:

      Altitude_Datum_Name: WGS84
      Altitude_Resolution: 0.0001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
      

7. How does the data set describe geographic features?

   Chandeleur_Islands_2016_IFB_NAD83_NAVD88g09_xyz.txt

   ASCII text file containing the processed 5-meter resolution interferometric swath bathymetry xyz samples transformed to the North American Datum of 1983 (NAD83) geodetic datum and North American Vertical Datum of 1988 (NAVD88) orthometric height, derived using the GEOID09 model. (Source: USGS)

   NAD83_X

   NAD83 X-coordinate (easting) of sample point, in meters (Source: USGS)

   Range of values
   Minimum:	318950.7884
   Maximum:	323215.7872
   Resolution:	1.0E-4

   NAD83_Y

   NAD83 Y-coordinate (northing) of sample point, in meters (Source: USGS)

   Range of values
   Minimum:	3321899.3783
   Maximum:	3328234.3770
   Resolution:	1.0E-4

   Data_Type

   IFB = Interferometric Bathymetry; SPCMSC identifier of bathymetry data type. (Source: USGS) IFB

   Year

   Year data were collected. (Source: USGS) 2016

   NAVD88g09

   NAVD88 (orthometric height) of sample point, in meters with respect to GEOID09. (Source: USGS)

   Range of values
   Minimum:	-8.7756
   Maximum:	-1.6590
   Resolution:	1.0E-4

   Chandeleur_Islands_2016_IFB_ITRF08_xyz.txt

   ASCII text file containing the WGS84(G1762) processed 5-meter resolution interferometric swath bathymetry xyz samples equivalent to the International Terrestrial Reference Frame of 2008 (ITRF08). (Source: USGS)

   ITRF08_X

   ITRF08 X-coordinate (easting) of sample point, in meters. (Source: USGS)

   Range of values
   Minimum:	318950
   Maximum:	323215
   Resolution:	1.0E-4

   ITRF08_Y

   ITRF08 Y-coordinate (northing) of sample point, in meters. (Source: USGS)

   Range of values
   Minimum:	3321900
   Maximum:	3328235
   Resolution:	1.0E-4

   Ellipsoid

   ITRF08 ellipsoid height of sample point, in meters. (Source: USGS)

   Range of values
   Minimum:	-37.148
   Maximum:	-29.89
   Resolution:	1.0E-3

   Data_Type

   IFB = Interferometric Bathymetry; SPCMSC identifier of bathymetry data type. (Source: USGS) Character string - IFB

   Year

   Year the data were collected. (Source: USGS) 2016

   Chandeleur_Islands_2016_IFB_NAD83_tracklines.shp

   Esri shapefile containing the survey tracklines for the interferometric swath bathymetry transformed to the North American Datum of 1983 (NAD83). (Source: Esri)

   FID

   Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.

   Shape

   Feature geometry. (Source: Esri) Polyline ZM is the geometry type defining the features.

   HypackLine

   Trackline name assigned by HYPACK acquisition software version 2014.0.9.47. For example, in 001_1640, 001 denotes the line number, and 1640 denotes the time HYPACK started recording the line. (Source: HYPACK)

   Range of values
   Minimum:	001_1640
   Maximum:	031_1556

   Trackline

   Trackline name assigned by field crew during the survey, these lines represent uncorrected GPS position data associated with each IFB trackline. (Source: USGS)

   Range of values
   Minimum:	l1f1
   Maximum:	l36f2

   Data_Type

   IFB = Interferometric Bathymetry; SPCMSC identifier of bathymetry data type. (Source: USGS) IFB

   Year

   Year data were collected. (Source: USGS) 2016

   Chandeleur_Islands_2016_IFB_ITRF08_tracklines.shp

   Esri shapefile containing the survey tracklines for the interferometric swath bathymetry referenced in the International Terrestrial Reference frame of 2008 (ITRF08). (Source: Esri)

   FID

   Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.

   Shape

   Feature geometry. (Source: Esri) Polyline ZM is the geometry type defining the features.

   Trackline

   Trackline name was assigned by field crew during the survey representing uncorrected GPS position data. (Source: USGS)

   Range of values
   Minimum:	l1f1
   Maximum:	l36f2

   HypackLine

   Trackline name assigned by HYPACK acquisition software version 2014. For example, in 001_1640, 001 denotes the line number, and 1640 denotes the time HYPACK started recording the line. (Source: HYPACK)

   Range of values
   Minimum:	001_1640
   Maximum:	031_1556

   Data_Type

   IFB = Interferometric Bathymetry; SPCMSC identifier of bathymetry data type. (Source: USGS) IFB

   Year

   Year data were collected. (Source: USGS) 2016

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Andrew S. Farmer
   • Jake J. Fredericks
   • Jennifer L. Miselis
   • Noreen A. Buster
   • Nancy T. DeWitt
   • Kyle W. Kelso
   • Chelsea A. Stalk
   • B.J. Reynolds
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?
   Jake J. Fredericks

   U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727)502-8000 (voice)

   jfredericks@usgs.gov

Why was the data set created?

The IFB zip archives contain processed sounding point data (xyz) and trackline shapefiles collected in June 2016 (FAN 2016-335-FA; subFAN 16BIM01) around the Chandeleur Islands, Louisiana. Additional survey and data details are available at https://cmgds.marine.usgs.gov/fan_info.php?fan=2016-335-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: 2016 (process 1 of 5)

   Swath Bathymetry Acquisition: The interferometric swath bathymetry data were collected aboard the R/V Sallenger in June 2016 using the SEA SWATHplus-H 468 kHz interferometric sonar system. The transducer system was fastened to a static pole mount deployed over the starboard side gunnel. The Novatel GPS antennas were mounted atop the cabin. Boat position and motion data were recorded in real-time using a CodaOctopus F190R+. The IMU was mounted underwater between the transducer heads to minimize lever arm geometry errors between observed depths and vessel motion. Real-time corrected positions were acquired via Marinestar HP DGPS subscription service from Fugro, Inc. Marinestar HP position correction data and motion data from the IMU were integrated with interferometric soundings using SWATHplus software, version 3.10.2.0, with positional and calibration offsets pre-defined by a session file (.sxs), allowing for real-time-corrected depths. Before deployment, all equipment offsets were measured. During the survey, all swath tracklines were recorded in SWATHplus raw data format (.sxr). A Valeport Mini Sound Velocity Sensor (miniSVS) 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 raw data format during acquisition providing a real-time speed of sound at the transducer while underway. In addition, a separate Mini Sound Velocity Profiler (Valeport miniSVP) was used to collect speed of sound profiles (water surface to seafloor) approximately every two hours throughout the survey as well as other areas of question such as rapid transitions in water depth. Person who carried out this activity:
   

   Jake J. Fredericks

   U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

   Physical Scientist/Hydrographic Technician

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   jfredericks@usgs.gov

   Date: 2016 (process 2 of 5)

   Swath Bathymetry Processing: Data were collected with SWATHplus-H and Bathyswath 3.10.2.0, an acquisition and initial processing program. Preliminary roll calibration trackline data were collected and processed using Bathyswath Swath Processor version 3.10.2.0 and Bathyswath Grid Processor software version 3.10.0.0. Instrument offsets and calibration values were input into the session file (.sxs) and the raw data files (.sxr) were then processed using the updated system configuration file containing roll calibration values, measured equipment offsets, acquisition parameters, navigation and motion from the F190R+, SOS at the sonar head, and SVP cast data. Calibration offsets and acoustic filtering utilized in Bathyswath was then applied to each raw data file to create a processed data file (.gsf), and then imported into advanced sounding data processing software CARIS HIPS and SIPS (CARIS) version 9.1. The initial real-time processing datum for the swath and backscatter data was WGS84, which is the acquisition datum for Marinestar HP position and navigation data. Within CARIS, outliers for the navigation data and processed soundings were removed using program filters. Remaining data outliers were then removed manually. Refraction editor was used to correct for sound velocity errors. A CARIS BASE surface with associated CUBE sample surface was created from the edited soundings. A CUBE hypothesis is the estimated value of a grid node representing all the soundings within a chosen resolution 5-meter grid-cell size weighted by uncertainty and proximity, giving the final value as a "sample" of the data within the specific grid cell. This algorithm allows for multiple grid-node hypotheses to be verified or overridden by the user while maximizing processing efficiency. A final visual inspection of the dataset in addition to Quality Assurance and Quality Control (QA/QC) procedures were implemented to ensure outliers and erroneous data points had been removed from the final BASE surface. In order to provide the dataset in a non-proprietary format, the final xyz data were exported as an ASCII comma-separated file. Person who carried out this activity:
   

   Jake J. Fredericks

   U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

   Physical Scientist/Hydrographic Technician

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   jfredericks@usgs.gov

   Data sources produced in this process:

   • Chandeleur_Islands_2016_IFB_ITRF08_XYZ.txt

   Date: 2016 (process 3 of 5)

   Datum Transformation: The text file Chandeleur_Islands_2016_IFB_ITRF08.txt was converted, using VDatum version 3.6, from ITRF08 to the NAD83 reference frame and NAVD88 orthometric height using the National Geodetic Survey (NGS) geoid model of 2009 (GEOID09). Person who carried out this activity:
   

   Andrew S. Farmer

   U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

   Physical Scientist/Hydrographic Technician

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   afarmer@usgs.gov

   Data sources used in this process:

   • Chandeleur_Islands_2016_IFB_ITRF08_xyz.txt

   Data sources produced in this process:

   • Chandeleur_Islands_2016_IFB_NAD83_NAVD88_GEOID09_xyz.txt

   Date: 2016 (process 4 of 5)

   The 16BIM01 IFB bathymetry trackline files were created from the ITRF08-equivalent (WGS84[G1762]), uncorrected x,y point files collected in Hypack version 14.0.9.47. The geographic data were saved as a Keyhole Markup Language Zipped (.kmz) file and later opened and converted into a layer (.lyr) file within ArcCatalog version 10.3.1. The layer file was then exported as a shapefile in ArcMap version 10.3.1. Using the XTools Pro extension, feature conversion tool, "make polylines from points" the x,y data point shapefile was converted into a polyline shapefile. Another trackline file was created in ArcMap by reprojecting the WGS84(G1762) data to NAD83. Data sources used in this process:

   • Raw Hypack x,y point files

   Data sources produced in this process:

   • Chandeleur_Islands_2016_IFB_ITRF08_tracklines.txt
   • Chandeleur_Islands_2016_IFB_NAD83_tracklines.txt

   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?
   Fredericks, Jake J., Buster, Noreen A., DeWitt, Nancy T., Kelso, Kyle W., and Miselis, Jennifer L., 20161221, Coastal Interferometric Swath Bathymetry Data Collected in 2015 from the Chandeleur Islands, Louisiana: U.S. Geological Survey Data Release doi:10.5066/F7NV9GC8.

   Online Links:

   • https://doi.org/10.5066/F7NV9GC8

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 was determined during data collection. This dataset was from one research cruise and was 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. Offsets between the Inertial Measurement Unit (IMU) and the Differential Global Positioning System (DGPS) antennas were measured and entered into the CodaOctopus F190R+ internal setup program. Offsets between sonar reference points and the IMU reference points were entered into the SWATHplus survey system. The DGPS correction was obtained from Marinestar High-precision (HP) differential global navigation satellite system, a satellite positioning service, from Fugro, Inc. This signal was received through the Coda Octopus F190R+ GPS antennas. These bathymetric data have not been independently verified for accuracy.
2. How accurate are the geographic locations?
   Navigation information was recorded in real-time kinematic mode via the CODA Octopus F190R+ Precision Attitude and Positioning System. Differential GPS correction was obtained through the Marinestar HP broadcast subscription from Fugro, Inc. The manufacturer's stated horizontal accuracy is 10 centimeters (cm) 95% of the time. The trackline position data were recorded using HYPACK version 14.09.47 hydrographic acquisition and processing software.
3. How accurate are the heights or depths?
   The manufacturer's stated vertical accuracy of Marinestar GPS subscription is 15 cm, 95% of the time. The Coda Octopus F190R+ inertial measurement unit (IMU), which integrates the Marinestar position with motion, measures vessel velocity (+/- 0.014 meters/second [m/s]), roll and pitch (less than 0.025 degrees), heading (1 m baseline 0.1 degrees), and heave (5 cm per meter (m) of depth). The vertical accuracy for the SWATHplus-H system varies with depth and across track range. At 57 m, it is accurate to 10 cm vertically. Maximum vertical transformation error reported by VDatum version 3.6 was 0.076158 m or 7.6158 centimeters for eastern Louisiana. The sum of the errors (+/- 0.013 m + +/-0.15 m + 0.076158 m) in the vertical direction is equal to +/-0.334 m or +/- 33.4 cm.
4. Where are the gaps in the data? What is missing?
   These are complete post-processed xyz bathymetric data points from acoustic swath data collected near the Chandeleur Islands, Louisiana, in June 2016.
5. How consistent are the relationships among the observations, including topology?
   This file represents the post-processed bathymetric data (xyz) collected during a 2016 swath bathymetry survey (2016-335-FA).

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:

These data should not be used for navigational purposes. 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)
   
   Jake J. Fredericks

   U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727)502-8000 (voice)

   jfredericks@usgs.gov
2. What's the catalog number I need to order this data set?
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?
   • Availability in digital form:

     Data format:

     ASCII, Shapefile (version 9.20) XYZ, SHP

     Network links:

     https://coastal.er.usgs.gov/data-release/doi-P993MBJK/data/Chandeleur_Islands_2016_IFB_ITRF08_xyz.zip https://coastal.er.usgs.gov/data-release/doi-P993MBJK/data/Chandeleur_Islands_2016_IFB_NAD83_NAVD88_GEOID09_xyz.zip https://coastal.er.usgs.gov/data-release/doi-P993MBJK/data/Chandeleur_Islands_2016_IFB_ITRF08_tracklines.zip https://coastal.er.usgs.gov/data-release/doi-P993MBJK/data/Chandeleur_Islands_2016_IFB_NAD83_tracklines.zip

   • Cost to order the data: None

Who wrote the metadata?

Dates:

Last modified: 23-Sep-2021

Metadata author:

Andrew S. Farmer

U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

Physical Scientist[FAS22]/Hydrographic Technician

600 4th Street South

St. Petersburg, FL

USA

(727) 502-8000 (voice)

afarmer@usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)