Archive of Side Scan Sonar and Swath Bathymetry Data Collected During USGS Cruise 13CCT04 Offshore of Petit Bois Island, Gulf Islands National Seashore, Mississippi, August 2014

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Frequently anticipated questions:


What does this data set describe?

Title:
Archive of Side Scan Sonar and Swath Bathymetry Data Collected During USGS Cruise 13CCT04 Offshore of Petit Bois Island, Gulf Islands National Seashore, Mississippi, August 2014
Abstract:
In August of 2013, the U.S. Geological Survey (USGS) conducted geophysical surveys offshore of Petit Bois Island, Mississippi. These efforts are a continued part of the U.S. Geological Survey Gulf of Mexico Science Coordination partnership with the U.S. Army Corps of Engineers (USACE) to assist the Mississippi Coastal Improvements Program (MsCIP) and the Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazards Susceptibility Project, by mapping the shallow geologic stratigraphic framework of the Mississippi Barrier Island Complex. These geophysical surveys will provide the data necessary for scientists to define, interpret, and provide baseline bathymetry and seafloor habitat for this area to aid scientists in predicting future geomorphological changes to the islands with respect to climate change, storm impacts, and sea level rise. Furthermore, these data combined with the geomorphological results will provide the properties and extent of local offshore sand sediment resources available for planning and execution of the Gulf Islands National Seashore barrier island restoration. The geophysical data were collected during one cruise (USGS Field Activity Numbers 13CCT04) aboard the University of Southern Mississippi Research Vessel Tommy Munro offshore along the gulf side of Petit Bois Island, Gulf Islands National Seashore, Mississippi. Data were acquired with the following equipment: a Systems Engineering and Assessment, Ltd., SWATHplus interferometric sonar (468 kilohertz (kHz)), an EdgeTech 424 (4-24 kHz), an EdgeTech 525i chirp sub-bottom profiling system, and a Klein 3900 sidescan sonar system. This report serves as an archive of the processed interferometric swath bathymetry and sidescan sonar data. Geographic information system data products include an interpolated digital elevation model, an acoustic backscatter mosaic, a trackline map, and point data files. Additional files include error analysis maps, Field Activity Collection System logs, and formal Federal Geographic Data Committee metadata. NOTE: These data are scientific in nature and are not to be used for navigation. Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Supplemental_Information:
The USGS Saint Petersburg Coastal and Marine Science Center (SPCMSC) - St. Petersburg, Fla., assigns a unique identifier to each cruise or field activity. For example, 13CCT04 tells us the data were collected in 2013 during the fourth field activity for that project in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the cruise ID.
  1. How might this data set be cited?
    U.S. Geological Survey, DeWitt, Nancy T., Flocks, James G., Kindinger, Jack L., Bernier, Julie C., Kelso, Kyle W., Wiese, Dana S., Finlayson, Dave P., and Pfeiffer, William R., 2014, Archive of Side Scan Sonar and Swath Bathymetry Data Collected During USGS Cruise 13CCT04 Offshore of Petit Bois Island, Gulf Islands National Seashore, Mississippi, August 2014: U.S. Geological Survey Data Series 917, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -88.543062
    East_Bounding_Coordinate: -88.319795
    North_Bounding_Coordinate: 30.194019
    South_Bounding_Coordinate: 30.075676
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 13-Aug-2013
    Ending_Date: 23-Aug-2013
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: multimedia presentation
  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 257 x 427 x 1, type Grid Cell
    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 00.00001. Longitudes are given to the nearest 00.00001. 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 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean Lower Low Water (MLLW)
      Depth_Resolution: 0.1
      Depth_Distance_Units: meter
      Depth_Encoding_Method: Implicit coordinate
  7. How does the data set describe geographic features?
    13CCT04_v2_IFB_04_2m_ITRF05_MLLW.txt
    Post-processed x,y,z interferometric bathymetry data at 2 meter resolution in ASCII text format. (Source: CARIS HIPS and SIPS v. 8.1)
    ITRF05_X
    The X or easting horizontal coordinate referenced to International Terrestrial Reference frame of 2005 (ITRF05). (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:351478
    Maximum:372764
    Units:meters
    ITRF05_Y
    The Y or northing horizontal coordinate referenced to International Terrestrial Reference frame of 2005 (ITRF05). (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:3328196
    Maximum:3340978
    Units:meters
    MLLW_Z
    The water depth in Mean Lower Low Water (MLLW). (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:3.676
    Maximum:19.246
    Units:meters
    Resolution:0.001
    Std_Dev
    Standard Deviation of the MLLW_Z measurement. (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.000
    Maximum:0.298
    Units:meters
    Node_Std_Dev
    Standard Deviation of the node from the BASE surface. (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.000
    Maximum:1.491
    Units:meters
    Uncertainty
    Uncertainty (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.1000
    Maximum:0.580
    Units:meters
    Entity_and_Attribute_Overview:
    Post-processed x,y,z interferometric bathymetry data at 2 meter resolution in ASCII text format. The x and y coordinates are referenced to the World Geodetic System of 1984 (WGS84). The and the z values are water level height referenced to Mean Lower Low Water (MLLW).
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/ds/###/
    13CCT04_CrossValid_IFB_WGS84_MLLW_Error.shp
    The cross validation report that is produced from the radial basis function process. The validation reports the measured value which is the x,y,z point data, the predicted value from the surface, and error value which is the differece between the two values. From this data the root mean square error (RMS) was calculated. (Source: Esri ArcGIS version 10.1)
    FID
    Internal feature number, Sequential unique whole numbers that are automatically generated (Source: Esri ArcGIS version 10.1)
    Range of values
    Minimum:0
    Maximum:11761695
    SHAPE
    Point Feature Geometry (Source: Esri ArcGIS version 10.1) Point ZM defining the features.
    Measured
    The post processed water level value (MLLW) that is used to create the digital elevation model. (Source: Esri ArcGIS version 10.1)
    Range of values
    Minimum:3.676
    Maximum:19.246
    Units:meters
    Resolution:0.001
    Predicted
    The radial basis function's predicted water level value based upon user entered variables. The predicted value is used to create the digital elevation model. (Source: Esri ArcGIS version 10.1)
    Range of values
    Minimum:3.499
    Maximum:20.154
    Units:meters
    Resolution:0.001
    Error
    The differenct between the measured value and the predicted value. (Source: Esri ArcGIS version 10.1)
    Range of values
    Minimum:-2.843
    Maximum:2.593
    Units:meters
    Resolution:0.001
    Error_Sqr
    The value in the error column squared. (Source: Esri ArcGIS version 10.1)
    Range of values
    Minimum:0.00
    Maximum:8.08
    Units:meters
    Source_ID
    Internal feature number, Sequential unique whole numbers that are automatically generated (Source: Esri ArcGIS version 10.1)
    Range of values
    Minimum:0
    Maximum:11761695
    Entity_and_Attribute_Overview:
    The cross validation report that is generated from Esri ArcGIS Geostatistical Radial Basis Function in which the measured value, the predicted value, and the error between the two values is reported. The predicted value is based upon the measured value (input data set) and the user defined criteria which dictates how the surrounding data values will be used in order to obtain the predicted value for the DEM. The x and y coordinates are referenced to the World Geodetic System of 1984 (WGS84). The and the z values are water level height referenced to Mean Lower Low Water (MLLW).
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/ds/###/
    13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part1of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part2of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part3of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part4of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part5of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part6of6.txt;
    Post-processed x,y,z interferometric bathymetry data at 2 meter resolution in ASCII text format. The horizontal reference frame is World Geodetic System 1984 (WGS84), and the vertical reference frame is Mean Lower Low Water (MLLW). (Source: CARIS HIPS and SIPS v. 8.1 and VDatum v. 3.2)
    WGS84(G1150)_X
    The X or Easting horizontal coordinate referenced to the World Geodetic System 1984 (WGS84). (Source: VDatum v. 3.2)
    Range of values
    Minimum:351477.997
    Maximum:367013.997
    Units:meters
    WGS84(G1150)_Y
    The Y or northing horizontal coordinate referenced to the the World Geodetic System 1984 (WGS84). (Source: VDatum v. 3.2)
    Range of values
    Minimum:3328195.9736
    Maximum:3330639.9736
    Units:meters
    MLLW_Z
    The water depth in Mean Lower Low Water (MLLW). (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:3.676
    Maximum:19.246
    Units:meters
    Resolution:0.001
    Std_Dev
    Standard Deviation of the MLLW_Z measurement. (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.000
    Maximum:0.298
    Units:meters
    Node_Std_Dev
    Standard Deviation of the node from the BASE surface. (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.000
    Maximum:1.491
    Units:meters
    Uncertainty
    Uncertainty (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.1000
    Maximum:0.580
    Units:meters
    Entity_and_Attribute_Overview:
    Using the transformation software VDatum version 3.2, the interferometric swath bathymetry data were transformed horizontally from ITRF05 to the World Geodetic System of 1984 version G1150 (WGS84_G1150). The vertical datum was not transformed and remained in MLLW. The single text file (13CCT04_v2_IFB_04_2m_ITRF05_MLLW.txt) had to be broken down into six segments for VDatum conversion. The vertical attributes named std_dev, node_std_dev, and uncertainty are carried over from CARIS export.
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/ds/###/
    13CCT04_v2_IFB_04_2m_NAD83_MLLW_part1of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part2of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part3of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part4of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part5of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part6of6.txt;
    Post-processed x,y,z interferometric bathymetry data at 2 meter resolution in ASCII text format. The horizontal reference frame is North American Datum of 1983 (NAD83) CORS 96 and the vertical reference frame is Mean Lower Low Water (MLLW). (Source: CARIS HIPS and SIPS v. 8.1 and VDatum v. 3.2)
    NAD83(CORS96)_X
    The X or Easting horizontal coordinate referenced to the North American Datum of 1983 (NAD83) CORS96. (Source: VDatum v. 3.2)
    Range of values
    Minimum:Range_Domain_Minimum
    Maximum:Range_Domain_Maximum
    Units:meters
    NAD83(CORS96)_Y
    The Y or northing horizontal coordinate referenced to the North American Datum of 1983 (NAD83) CORS96. (Source: VDatum v. 3.2)
    Range of values
    Minimum:Range_Domain_Minimum
    Maximum:Range_Domain_Maximum
    Units:meters
    MLLW_Z
    The water depth in Mean Lower Low Water (MLLW). (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:3.676
    Maximum:19.246
    Units:meters
    Resolution:0.001
    Std_Dev
    Standard Deviation of the MLLW_Z measurement. (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.000
    Maximum:0.298
    Units:meters
    Node_Std_Dev
    Standard Deviation of the node from the BASE surface. (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.000
    Maximum:1.491
    Units:meters
    Uncertainty
    Uncertainty (Source: CARIS HIPS and SIPS v. 8.1)
    Range of values
    Minimum:0.1000
    Maximum:0.580
    Units:meters
    13CCT04_IFB_50_WGS84_G1150_MLLW_DEM_raster2point.shp
    The raster file 13CCT04_IFB_50_WGS84_G1150_MLLW_DEM.tif exported as a point file. (Source: Esri ArcGIS point file)
    FID
    Internal feature number (Source: Esri ArcGIS 10.1) Sequential unique whole numbers that are automatically generated
    Shape
    Point Feature Geometry (Source: Esri ArcGIS 10.1) Point defining the feature
    POINTID
    Internal feature number (Source: Esri ArcGIS 10.1)
    Range of values
    Minimum:1
    Maximum:83329
    GRID_CODE
    MLLW value at the center of every 50-m spaced grid node. (Source: Esri ArcGIS 10.1)
    Range of values
    Minimum:4.01
    Maximum:18.67
    Units:meters
    W84G1150_X
    The X or Easting horizontal coordinate referenced to the World Geodetic System 1984 (WGS84). (Source: Esri ArcGIS 10.1)
    Range of values
    Minimum:351477.997
    Maximum:372777.997
    Units:meters
    W84G1150_Y
    The Y or northing horizontal coordinate referenced to the the World Geodetic System 1984 (WGS84). (Source: Esri ArcGIS 10.1)
    Range of values
    Minimum:3328197.29605
    Maximum:3340997.29605
    Units:meters
    Entity_and_Attribute_Overview:
    The raster file 13CCT04_IFB_50_WGS84_G1150_MLLW_DEM.tif exported as a point file using Esri ArcGIS "raster to point" conversion tool. The x and y values were then populated using the XTools Pro version 10 table operations named add x,y, and z.
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/ds/###/
    13CCT04_IFB_tracklines.shp
    ESRI shapefile containing the survey tracklines for the interferometric swath bathymetry data collected in August 2013 off of Petit Bois Island, Gulf Islands National Seashore, Mississippi. (Source: USGS)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Coordinates defining the features.
    HYPACKLine
    String (Source: HYPACK) Line number in survey generated by HYPACK
    DOY
    Text (Source: Esri) The 2013 day of year that the trackline was surveyed.
    Year
    String. (Source: Esri) Year survey completed
    Lenth_m
    Length on survey line, in meters (Source: Esri)
    Range of values
    Minimum:63.37
    Maximum:1994.76
    Units:meters
    Resolution:0.01
    Entity_and_Attribute_Overview:
    HYPACK tracklines exported from HYPACK in Keyhole Markup Language (KML) format and imported into ESRI ArcGIS version 10.1 and projected from the GPS acquisition datum (World Geodetic System of 1984, WGS84 G1150) to the North American Datum of 1983 (NAD83), Universal Transverse Mercator (UTM) Zone 16 North and saved to ESRI shapefile format.
    Entity_and_Attribute_Detail_Citation:

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
    • Nancy T. DeWitt
    • James G. Flocks
    • Jack L. Kindinger
    • Julie C. Bernier
    • Kyle W. Kelso
    • Dana S. Wiese
    • Dave P. Finlayson
    • William R. Pfeiffer
  2. Who also contributed to the data set?
    U.S. Geological Survey, Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center (SPCMSC)
  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 50-meter cell size digital elevation model is an interpretive product that was derived from the processed interferometric swath bathymetry data collected in August of 2014 off of Petit Bois Island, Gulf Islands National Seashore, Mississippi.

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: 2013 (process 1 of 11)
    Swath Bathymetry Acquisition: The interferometric swath bathymetry data were collected aboard the RV Tommy Munro using a SEA SWATHplus-H 468 kHz interferometric sonar system mounted on the starboard side of the vessel. Boat position and motion data were recorded in real-time with 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 associated vessel motion. Real-time corrected positions were acquired with an 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 versions 3.7.17, with positional and calibration offsets pre-defined by a session file(.sxs), allowing for real-time- corrected depths. During the survey, all swath tracklines were recorded in SEA SWATHplus 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 SOS 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: 2013 (process 2 of 11)
    Side Scan Sonar Acquisition: Side scan sonar was collected simulataneously as the interferometric data using the Klein 3900 dual-frequency side scan sonar system. It was towed off the port side of the RV Tommy Munro approximately 5 meters astern. SSS data were acquired and recorded using Klein SonarPro software (Klein Associates, Inc.) and manage cable out and layback offsets. Horizontal offset values between the side scan sonar towfish and the DGPS antennas were entered into Sonar Pro. The towfish motion was measured dynamically by internal sensors of the instrument, and towfish altitude (height from seafloor) was calculated by SonarPro. Data files were recorded in an Extended Triton Format (XTF). 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: 2013 (process 3 of 11)
    Swath Bathymetry Processing: Position data recorded by the Coda-Octopus F190R IMU system were corrected in real time via the OmniSTAR HP differential navigation system. 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 ellipsoid height and position, representing the elevation of the seafloor with respect to the geodetic reference frame ITRF05 across the swath range. SWATHplus served as both an acquisition software and initial processing software. Preliminary roll calibration trackline data were collected and processed with Systems Engineering and Assessment Ltd SWATHplus and Grid Processor software version 3.7.17. Instrument offset and calibration values were entered into the session file (.sxs) and the raw data files (.sxr) were processed using the updated system configuration containing roll calibration values, measured equipment offsets, acquisition parameters, navigation and motion from the F190R, SOS at the sonar head, and SVP cast data. Any calibration offsets or acoustic filtering applied in SWATHplus was also written to the processed data file (.sxp). The initial real-time processing datum for the swath and backscatter data was ITRF05, which is the acquisition datum for OmniSTAR HP position and navigation data. All processed data files (.sxp) were imported into CARIS HIPS and SIPS version 8.1 and finalized in version 8.1.7. The NOAA tide zone model and associated verified six minute tide data were applied using the CARIS Load Tide tool. The total propogated uncertainty was calculated. The original sounding data were edited for outliers using the CARIS Swath Editor tool and associated depth filters. Remaining outliers were then deleted manually. A CARIS BASE (Bathymetry with Associated Statistical Error) surface with the associated CUBE (Combined Uncertainty and Bathymetry Estimator) sample surface was created from the edited soundings dataset. A BASE hypothesis is the estimated value of a grid node representing all the soundings within a chosen resolution or grid-cell size (for example, 2 m) weighted by uncertainty and proximity, giving the final value as a "sample" of the data within the specific grid cell. This algorithm allows multiple grid-node hypotheses to be verified or overridden by the user while maximizing processing efficiency. A 2-m resolution CUBE surface was created to perform initial CUBE hypothesis editing followed by a higher 1-m resolution BASE surface cleaning using the CARIS Subset Editor tool. The 2-m resolution BASE surface sample x,y,z data were exported as ASCII in the ellipsoid datum of ITRF05 and MLLW vertical datum. 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:
    • SWATHplus post processed files (*.sxp), verified tide station data in text format (*.txt), and tide zone model in CARIS format (*.zdf).
    Data sources produced in this process:
    • 13CCT04_v2_IFB_04_2m_ITRF05_MLLW.txt
    Date: 2014 (process 4 of 11)
    Interferometric Backscatter Processing: The interferometric backscatter (IFB) was processed using SXPTools (build 175). SXPTools is a research project of the US Geological Survey that uses command line programs to enhance the quality of the backscatter from SEA SWATHplus processed data files using an empirical gain normalization scheme (Finlayson, USGS, unpub. data, 2009). The processed (.sxp) files were gridded using MBSystem (Version 5.3) and exported in ESRI ASCII Grid format. The grid was imported into ESRI's ArcGIS Version 10.2, converted to a raster file with the ASCII to Raster Tool. The final mosaic was exported in GeoTIFF format referenced to ITRF05 UTM Zone 16N. 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:
    • SWATHplus post processed files (*.sxp).
    Data sources produced in this process:
    • 13CCT04_IBS_01_ITRF04.tif
    Date: 2013 (process 5 of 11)
    Side Scan Sonar Processing: The side scan sonar acoustic bakscatter data from the Klein 3900 was imported into SonarWiz5 version 5.06, and bottom tracking was applied creating a slant range corrected record to define the seafloor 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. A backscatter mosaic was created from the individual SSS lines and adjusted for contrast and brightness. The final mosaic was exported in GeoTIFF format and imported into Esri's ArcGIS version 10.2 project, where the histogram was adjusted to enhance the display of seafloor surface material. Missing tracklines from the mosaic grid are a direct result of equipment issues with the Klein 3900 during the cruise. Data was either corrupt, noisy, or not collected in these areas 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 SSS data files in an Extended Triton Format (XTF).
    Data sources produced in this process:
    • 13CCT04_IBS_01_ITRF04.tif
    Date: 2014 (process 6 of 11)
    Datum transformation: Using the transformation software VDatum version 3.2, the interferometric swath bathymetry data were transformed horizontally from ITRF05 to the World Geodetic System of 1984 version G1150 (WGS84_G1150) and second transformed into the North American Datum of 1983 (NAD83) reference frame. The vertical datum was not transformed and remained in MLLW. The single text file (13CCT04_v2_IFB_04_2m_ITRF05_MLLW.txt) had to be broken down into six segments for VDatum conversion. 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:
    • 13CCT04_v2_IFB_04_2m_ITRF05_MLLW_part1of6.txt; 13CCT04_v2_IFB_04_2m_ITRF05_MLLW_part2of6.txt; 13CCT04_v2_IFB_04_2m_ITRF05_MLLW_part3of6.txt; 13CCT04_v2_IFB_04_2m_ITRF05_MLLW_part4of6.txt; 13CCT04_v2_IFB_04_2m_ITRF05_MLLW_part5of6.txt; 13CCT04_v2_IFB_04_2m_ITRF05_MLLW_part6of6.txt
    Data sources produced in this process:
    • 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part1of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part2of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part3of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part4of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part5of6.txt; 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_part6of6.txt
    • 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part1of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part2of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part3of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part4of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part5of6.txt; 13CCT04_v2_IFB_04_2m_NAD83_MLLW_part6of6.txt
    Date: 2014 (process 7 of 11)
    Gridding Bathymetric data: Using Esri ArcGIS, the swath soundings were imported into ESRI’s ArcMap version 10.1 and gridded using the Geostatistical Analyst Tool's "radial basis function". This allowed the user to adjust interpolation parameters with regard to real data spatial resolution and orientation when predicting values. This method provided for a less biased representation of the dataset as a whole. A cross-validation report can be generated when using the radial basis function that helps the user understand how well the model will predict data values at locations without data points. In general the cross-validation takes one point and predicts its position using the weighted surrounding data values. This predicted value is compared against the actual value of that data point and general statistics are computed. The validation report for the swath bathymetry 50-m grid is listed below. The radial basis function surface was exproted to a raster file. A bounding polygon representing the extent of survey tracklines was created and converted into a raster mask using the ArcGIS "polygon to raster" conversion tool. The DEM was then clipped to the raster mask using the ArcGIS Spatial Analyst "extract by raster mask" tool. It is common, in large-area, shallow water surveys, to find wide data gaps between tracklines relative to the swath width surveyed. To minimize this concern in the final DEM, the ArcGIS Spatial Analyst "neighborhood" low-pass raster- data filter was applied. The raster image was then exported as a GeoTIFF. 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:
    • 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_txt: This text file is the combination of files 13CCT04_v2_IFB_04_2m_WGS84(G1150)_MLLW_partXof6.txt (Where X is 1 through 6).
    Data sources produced in this process:
    • 13CCT04_IFB_04_WGS84_G1150_MLLW_DEM.tif
    Date: 2014 (process 8 of 11)
    Error: A comparison of the DEM versus the sounding (x,y,z point data) was plotted to evaluate how well the DEM represented the original sounding data quantitatively and spatially. This was done using the error results from the cross validation report that is produced from the radial basis function process. The validation reports the measured value which is the x,y,z point data, the predicted value from the surface, and error value which is the differece between the two values. From this data the root mean square error (RMS) was calculated. The difference between the DEM and the original sounding values were plotted, color coded, and placed against the backdrop of the DEM. This provided a visual aspect of the spatial representation of error. 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:
    • 13CCT04_CrossValid_IFB_WGS84_MLLW.shp
    Data sources produced in this process:
    • 13CCT04_CrossValid_IFB_WGS84_MLLW_Error.shp
    Date: 2014 (process 9 of 11)
    DEM conversion from Raster to Point: The 50-m DEM was converted to a point shapefile using Esri's ArcMap "Raster to Point" conversion tool. 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:
    • raster file named = ifb84rbf50rmf
    Data sources produced in this process:
    • 13CCT04_IFB_50_WGS84_G1150_MLLW_DEM_raster2point.shp
    Date: 2014 (process 10 of 11)
    DEM point shapefile conversion to text file: The point shapefile was then exported to a text file. 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:
    • 13CCT04_IFB_50_WGS84_G1150_MLLW_DEM_raster2point.shp
    Data sources produced in this process:
    • 13CCT04_IFB_50_WGS84_G1150_MLLW_DEM_raster2point.txt
    Date: 2013 (process 11 of 11)
    Trackline Map Creation: The tracklines were exported from HYPACK in Keyhole Markup Language (KML) format and imported into ESRI ArcGIS version 10.1. In ESRI ArcGIS, the trackline data were projected from the GPS acquisition datum (World Geodetic System of 1984, WGS84 G1150) to the North American Datum of 1983 (NAD83), Universal Transverse Mercator (UTM) Zone 16 North and saved to ESRI shapefile format. Data sources used in this process:
    • HYPACK raw bathymetry files (*.RAW)
    Data sources produced in this process:
    • 13CCT04_IFB_tracklines.shp
  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. The interferometric swath bathymetry data were collected during concurrent research cruises in August, 2013. Methods are employed to maintain data collection consistency aboard various platforms. During mobilization, each piece of equipment is isolated to obtain internal and external offset measurements with respect to the survey platform. All critical measurements are recorded manually and digitally and entered into their respective programs for calibration. Once calibration is complete and the calibration status is considered acceptable, survey operations commence. Efforts are made to use the same equipment and software versions on the system; however, upgrades and changes can occur and require additional setup, measurements, and notation. For the interferometric swath bathymetry, offsets between the sonar head and the DGPS antennas were measured and entered into the CodaOctopus F190R internal setup program. DGPS was provided through the OmniSTAR High Performance wide-area GPS service. These bathymetric data have not been independently verified for accuracy.
  2. How accurate are the geographic locations?
    The 2-sigma (95%) horizontal accuracy of the OmniSTAR HP navigation as specified by OmniSTAR, is +/- 10 cm.
  3. How accurate are the heights or depths?
    Six minute verified data was obtained from the Pascagoula NOAA Lab station 8741533 and the Bay Waveland Yacht Club station ID 8747437 for the time from 8-15-2013 to 8-23-2014. The data and the tide model were applied to the interferometric bathymetric data within CARIS HIPS and SIPS during post processing. The total propagated error (TPE) measurement for this tide zone region is a combinaion of systemic error, radom errors, and datum errors. Systemic errors can include datum computation errors, data processing errors, and radom errors associated with tidal zone models, water level guage measurments, and dynamic ocean effects. Datum errors can include errors associated with the physical leveling and processing of the tide station itself. The TPE for this zone = 0.### meters. The RMS associated with the tidal zoning is = 0.### meters. All errors are at the 95% confidence interval.
  4. Where are the gaps in the data? What is missing?
    This is a completely processed digital elevation model representing an interpolated bathymetric surface derived from the acoustic interferometric swath bathymetry data.
  5. How consistent are the relationships among the observations, including topology?
    The interferometric swath bathymetry data were collected during one research cruises in August, 2013. Refer to the online data series linkage for field logs, vessel platform descriptions, and other survey information. This dataset was created to provide bathymetric grid of the processed data. The digital elevation model is 50-meter cell-size resolution; data gaps between acquisition tracklines are predicted values generated by the gridding algorithm.

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 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 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?
    These shapefiles were created for use with Esri ArcGIS software.

Who wrote the metadata?

Dates:
Last modified: 08-Jun-2016
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 Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/13CCT04_metadata.faq.html>
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