Multibeam Echosounder, Reson T-20P tracklines, USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (Esri polyline shapefile, GCS WGS 84)

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Frequently anticipated questions:

What does this data set describe?

Title:
Multibeam Echosounder, Reson T-20P tracklines, USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (Esri polyline shapefile, GCS WGS 84)
Abstract:
High resolution bathymetric, sea-floor backscatter, and seismic-reflection data were collected offshore of southeastern Louisiana aboard the research vessel Point Sur on May 19-26, 2017, in an effort to characterize mudflow hazards on the Mississippi River Delta front. As the initial field program of a research cooperative between the U.S. Geological Survey, the Bureau of Ocean Energy Management, and other Federal and academic partners, the primary objective of this cruise was to assess the suitability of sea-floor mapping and shallow subsurface imaging tools in the challenging environmental conditions found across delta fronts (for example, variably distributed water column stratification and widespread biogenic gas in the shallow subsurface). Approximately 675 kilometers (km) of multibeam bathymetry and backscatter data, 420 km of towed chirp data, and 550 km of multichannel seismic data were collected. Varied mudflow (gully, lobe), prodelta morphologies, and structural features were imaged in selected survey areas from Pass a Loutre to Southwest Pass.
Supplemental_Information:
Additional information on the field activity is available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-003-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 2018, Multibeam Echosounder, Reson T-20P tracklines, USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (Esri polyline shapefile, GCS WGS 84): data release DOI:10.5066/F7X929K6, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Baldwin, Wayne E., Ackerman, Seth D., Worley, Charles R., Danforth, William W., and Chaytor, Jason D., 2018, High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA: data release DOI:10.5066/F7X929K6, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Baldwin, W.E., Ackerman, S.D., Worley, C.R., Danforth, W.W., and Chaytor, J.D, 2018, High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA: U.S. Geological Survey data release, https://doi.org/10.5066/F7X929K6.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -89.554925
    East_Bounding_Coordinate: -88.862743
    North_Bounding_Coordinate: 29.429651
    South_Bounding_Coordinate: 28.776182
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5a946c1ae4b069906068fb8a/?name=2017-003-FA_T20P_Tracklines_browse.jpg (JPEG)
    Thumbnail image of multibeam echosounder tracklines from the Mississippi River Delta front offshore of southeastern Louisiana.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 21-May-2017
    Ending_Date: 26-May-2017
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: 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 Vector data set. It contains the following vector data types (SDTS terminology):
      • string (138)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_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 1/298.257224.
  7. How does the data set describe geographic features?
    2017-003-FA_T20P_Tracklines
    T20P multibeam echosounder tracklines for survey 2017-003-FA along the Mississippi River Delta front. (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Coordinates defining the features.
    LineName
    HYPACK HYSWEEP HSX filename for the T20P MBES trackline in the format: HYSWEEP planned line number (i.e. '001_') + UTC start time (HHMM format, i.e. '0227'). These lines were used for bathymetry data processing. (Source: U.S. Geological Survey) Character set
    LineName7k
    Reson SeaBat User Interface s7k filename for the T20P MBES trackline in the format: UTC start date and time (YYYYMMDD_HHMMSS format, i.e. '20170521_035424'). The actual files names for the primary and secondary T20P units are prepended with 'M_' or 'S_', respectively. #N/A indicated no Reson s7k file was recorded. These lines were used for backscatter data processing. (Source: U.S. Geological Survey) Character set
    YJD_start
    Year and Julian date at the start of the survey line in the format: YYYY-JD; where Julian day is the integer number (although recorded here in text string format) representing the interval of time in days since January 1 of the year of collection. In the case of split lines (i.e. those with and "a" or "b" appended to 'LineName') YYYY-JD is accurate for the individual sections. (Source: U.S. Geological Survey) Character set
    JDUT_start
    Julian day and UTC time at the start of the survey line in the format: JD:HH:MM:SS; Julian day is the integer number (although recorded here in text string format) representing the interval of time in days since January 1 of the year of collection. In the case of split lines (i.e. those with an "a" and "b" appended to 'LineName') JD:HH:MM:SS is accurate for the individual sections. (Source: U.S. Geological Survey) Character set
    YJD_end
    Year and Julian date (YYYY-JD) at the end of the survey line. In the case of split lines (i.e. those with and "a" or "b" appended to 'LineName') YYYY-JD is accurate for the individual sections. (Source: U.S. Geological Survey) Character set
    JDUT_end
    Julian day and UTC time (JD:HH:MM:SS) at the end of the survey line. In the case of split lines (i.e. those with an "a" and "b" appended to 'LineName') JD:HH:MM:SS is accurate for the individual sections. (Source: U.S. Geological Survey) Character set
    SurveyID
    WHCMSC field activity identifier (e.g. "2017-003-FA" where 2017 is the survey year, 003 is survey number of that year, and FA is Field Activity). (Source: U.S. Geological Survey) Character set
    VehicleID
    Survey vessel name. (Source: U.S. Geological Survey) Character set
    DeviceID
    Sonar device used to collect MBES data. (Source: U.S. Geological Survey) Character set
    Length_km
    Length of swath data line in kilometers (UTM Zone 16N, WGS 84) calculated in the SQLite database. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.02
    Maximum:14.61
    Units:kilometers
    Resolution:0.01

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?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Wayne E. Baldwin
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    US

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

Why was the data set created?

This dataset contains trackline navigation for approximately 675 km of multibeam echosounder bathymetry and backscatter data collected by the U.S. Geological Survey during cruise 2017-003-FA along the Mississippi River Delta front offshore of southeastern Louisiana. This information can help spatially correlate the bathymetry and backscatter data with other with other geophysical and sample data.

How was the data set created?

  1. From what previous works were the data drawn?
    Reson T20P multibeam echosounder data (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw multibeam echosounder data.

    Type_of_Source_Media: disc
    Source_Contribution:
    Multibeam echosounder bathymetry, backscatter, and water column data were collected using dual Reson T20P MBES. The pair of Mills Cross 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 side of the R/V Point Sur so that the sonar arrays were oriented athwart ships (primary and secondary arrays facing outward and down to port and starboard, respectively) and located approximately 3.04 m below the waterline when deployed. Vessel navigation and attitude data were acquired with an Applanix POS MV Wavemaster (model 220, V5) configured with two AeroAntenna Technologies GPS antennas located at either end of a 2-m baseline, which was oriented fore and aft and mounted atop the MBES pole approximately amidships on the starboard side of vessel, and the wet pod MRU mounted atop the sonar bracket just aft of the pole. An AML Micro X SV mounted on the sonar bracket monitored sound speed near the sonars during acquisition, and an ODIM MVP30 moving vessel profiler (MVP), mounted on the stern, was used to collect water column sound speed profiles at 1 to 5 hour intervals while underway (See shapefile 2017-003-FA_MVPdata.shp available from the larger work citation). The Reson SeaBat User Interface (version 5.0.0.6) was used to control the sonars, which were operated in intermediate mode at full power (220 db), with frequency modulated pulses between 200 to 300 kHz. The range of the 1024 across track beams formed by the sonars were adjusted manually depending on water depth, and resulted in combined swath widths of 60 to 500 meters or typically 3 to 6 times the water depth. Data were monitored and recorded using the Reson SeaBat User Interface (version 5.0.0.6) and HYPACK/HYSWEEP (version 2017, 17.1.3.0). The SeaBat User Interface logged the navigation, attitude, bathymetry, time-series backscatter, and water column data to s7k format files for each sonar. HYSWEEP logged the navigation, attitude, and bathymetry data for both sonars to a single HSX format file, the time series backscatter data for both sonars to a single 7k format file, and water column data to 7k format files for each sonar. HYPACK HSX data were used to produce the final processed bathymetry grids, and Reson SeaBat User Interface s7k data were used to produce the final processed backscatter mosaics.
  2. How were the data generated, processed, and modified?
    Date: May-2017 (process 1 of 7)
    Shipboard multibeam processing within Caris HIPS (version 10.2) consisted of the following flow:
    1) Caris HIPS projects (version 10.2) were created to process T20P data in the HSX and s7k formats. Projection information was set to Universal Transverse Mercator (UTM) Zone 16N, WGS 84 in each.
    2) Vessel configuration files were created in each Caris project for the R/V Point Sur, which included relevant linear and angular installation offsets for each T20P unit as well as vendor specified uncertainty values for each of the survey sensors.
    3) Raw files were imported to the Caris projects using the Import/Conversion Wizard.
    4) Delayed heave data from raw POS MV files were used to update HIPS survey lines using the import auxiliary data function.
    This process step and all subsequent process steps were conducted by the same person - Wayne Baldwin. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Wayne Baldwin
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Nov-2017 (process 2 of 7)
    Post-cruise processing within Caris HIPS (version 10.4) consisted of the following flow:
    1) Post-processed navigation, vessel attitude, and GPS height data from POSPac SBET files, and post-processed rms attitude error data from POSPac smrmsg files were used to update HIPS survey lines using the import auxiliary data function (In some instances, loading of the POSPac SBET data necessitated splitting the HIPS survey lines due to small gaps in the post-processed data; e.g. a and b files for 329_0409, 326_0842, 322_1355, and 322_1935; Additionally, SBET data would not load into data from 5/21/2017 (JD141) between 02:27 and 13:08, and GPS heights were loaded from the raw POS MV files).
    2) Where applicable, lines were updated with Applanix SBET set as the navigation source, and navigation was reviewed and edited as needed using the Navigation Editor tool.
    Date: Dec-2017 (process 3 of 7)
    Use AWK, Python, and Shell scripts to extract and reformat the navigation fixes stored in the Caris HIPS database and add them to a geospatial SQLite (version 3.21.0) database:
    1) Extract navigation for each line in Caris HDCS directory using the Caris program printfNav for all the lines. (Extracted navigation file is tab-delimited in format YYYY-JD HH:MM:SS:FFF DD.LAT DD.LONG SSSSS_VVVVV_YYYY-JD_LLLL AR where YYYY=year, JD=Julian Day, HH=hour, MM=minute, SS=seconds, FFF=fractions of a second, DD.LAT=latitude in decimal degrees, DD.LONG=longitude in decimal degrees, SSSSS=survey name, VVVVV=vessel name, LLLL=linename, AR=accepted or rejected navigation fix). This step creates the directory of TXT navigation files for each survey line in the Caris project
    2) The output TXT files from the printfNav process are parsed to remove rejected navigation records then reformatted into CSV files containing additional fields for survey ID, vessel name, and system name using Shell and AWK scripts
    3) A Python script (pySQLBathNav) runs on each reformatted CSV file parsing the file from each record and adding points to a SQLite database (which is created if it does not already exist). The pySQLBathNav script creates both point and polyline navigation for each survey line.
    Date: Dec-2017 (process 4 of 7)
    Create Esri shapefile containing the polyline data:
    The T20P polyline features were added (Add Data) into ArcMap (version 10.3.1) from the SQLite database, then exported (Right click on database feature class > Data > Export Data) to the new Esri polyline shapefile 2017-003-FA_T20P_Tracklines.shp
    Date: Dec-2017 (process 5 of 7)
    Create field for Reson SeaBat User Interface s7k filenames in shapefile attribute table:
    A new attribute field named "LineName7k" was added to the shapefile attribute table and manually populated with the name of the Reson SeaBat User Interface s7k filename corresponding to the Hypack Hysweep HSX file listed in the "LineName" field.
    Date: Dec-2017 (process 6 of 7)
    Rename shapefile attribute table fields:
    XTools Pro (version 12.0) for ArcGIS desktop was used (TABLE OPERATIONS - TABLE RESTRUCTURE) to rename some attribute field headings in the polyline shapefile's attribute table. 'Year_JD_ini' was changed to 'YJD_start', 'JD_UTC_ini' was changed to 'JDUT_start', 'Year_JD_end' was changed to 'YJD_end', and 'JD_UTC_end' was changed to 'JDUT_end'. The remaining field headers were unchanged.
    Date: 07-Aug-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?
  2. How accurate are the geographic locations?
    Navigation data were acquired using the WGS 84 coordinate system with an Applanix POS MV Wavemaster (model 220, V5), which blends Global Navigation Satellite Systems (GNSS) with acceleration data from a Motion Reference Unit (MRU) and GPS azimuthal heading. The POS MV was configured with two AeroAntenna Technologies GPS antennas located at either end of a 2-m baseline, which was oriented fore and aft and mounted atop the MBES pole, approximately amidships on the starboard side of vessel. DGPS positions were obtained from the primary antenna located on the forward end of the baseline, and the positional offsets between the antenna and the navigational reference point (the POS MV IMU) were accounted for in the Applanix POSView (version 8.60) acquisition software. DGPS positions are horizontally accurate to 0.5 - 2 meters, but accuracy can increase to less than 10 cm after post-processing with Applanix POSPac (version 8.1).
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This shapefile includes trackline navigation for all the multibeam echosounder data collected during the cruise, except for the time periods 19:19 (UTC) 5/21/17 (JD141) - 02:20 5/22/17 (JD142) and 22:52 5/23/17 (JD143) - 23:03 5/23/17 (JD143), which were held from publication at the request of a cooperating agency. While the line navigation for all the data are included in this shapefile, all the data are not included in the final bathymetry grids or backscatter mosaics.
  5. How consistent are the relationships among the observations, including topology?
    Multibeam echosounder (MBES) data were collected almost continuously throughout the cruise, but acquisition was suspended briefly during file changes or for longer periods during turns and system calibration, malfunction, or troubleshooting. Gaps between the polyline features in this shapefile reflect those time periods where data were not recorded or were held from publication. The columns "LineName" and "LineName7k" in the attribute table contain the filenames for equivalent MBES files recorded in the HYPACK HYSWEEP (HSX format) and ResonUI (s7k format) acquisition software, respectively. Navigation for each of the file formats is identical (though files may differ in start or end times by several seconds) and represented by a single polyline. In some instances, loading of the POSPac SBET data necessitated splitting the HIPS survey lines due to small gaps in the post-processed data; e.g. a and b files for 329_0409, 326_0842, 322_1355, and 322_1935; Additionally, SBET data would not load into data from 5/21/2017 (JD141) between 02:27 and 13:08, and GPS heights were loaded from the raw POS MV files. No equivalent s7k format files were recorded for HSX lines 001_0227, 002_0242, 003_0257, or 101_1827.

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. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Federal Center
    Denver, CO

    1-888-275-8747 (voice)
  2. What's the catalog number I need to order this data set? USGS data release 2017-003-FA multibeam echosounder trackline data from the Mississippi River Delta front area: incudes the shapefile 2017-003-FA_T20P_Tracklines.shp, the browse graphic 2017-003-FA_T20P_Tracklines_browse.jpg, and the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file 2017-003-FA_T20P_Tracklines_meta.xml.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm 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?
  5. What hardware or software do I need in order to use the data set?
    To utilize these data, the user must have software capable of reading shapefile format, or GIS software capable of utilizing web mapping or feature services.

Who wrote the metadata?

Dates:
Last modified: 07-Aug-2020
Metadata author:
U.S. Geological Survey
Attn: Wayne E. Baldwin
Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2226 (voice)
(508) 457-2310 (FAX)
wbaldwin@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_F7X929K6/2017-003-FA_T20P_Tracklines_meta.faq.html>
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