Single Beam Bathymetry XYZ Data Collected in June 2015 from the Chandeleur Islands, Louisiana

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?
   U.S. Geological Survey, 2017, Single Beam Bathymetry XYZ Data Collected in June 2015 from the Chandeleur Islands, Louisiana:.

   Online Links:

   • https://pubs.usgs.gov/ds/1039/ds1039_data.html

   This is part of the following larger work.
   Stalk, Chelsea A., DeWitt, Nancy T., Bernier, Julie C., Kindinger, Jack L., Flocks, James G., Miselis, Jennifer L., Locker, Stanley D., Kelso, Kyle W., and Tuten, Thomas M., 2017, Coastal single beam Bathymetry Data Collected in 2015 from the Chandeleur Islands, Louisiana: U.S. Geological Survey Data Series 1039, U.S. Geological Survey, St. Petersburg, Florida.

   Online Links:

   • https://doi.org/10.3133/ds1039

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -89.082749
   East_Bounding_Coordinate: -88.756262
   North_Bounding_Coordinate: 30.118907
   South_Bounding_Coordinate: 29.552392
   

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

   Beginning_Date: 17-Jun-2015

   Ending_Date: 24-Jun-2015

   Currentness_Reference:

   data collection interval

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

   Geospatial_Data_Presentation_Form: ASCII digital data
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      
   2. What coordinate system is used to represent geographic features?
      
7. How does the data set describe geographic features?

   15BIM01_SBB_Level_03_1039_ITRF00.txt

   ASCII text file containing the processed single beam bathymetry x,y,z data in their native format of WGS84 (ITRF00) Ellipsoid height as acquired by the R/V Sallenger (15BIM01). (Source: USGS)

   Shape

   Feature geometry (Source: Esri) Point ZM is the geometry type defining the feature

   ITRF00_Y

   WGS84 (ITRF00) Y-coordinate (northing) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	3270978.296
   Maximum:	3333278.111
   Resolution:	0.0001

   ITRF00_X

   WGS84 (ITRF00) X-coordinate (easting) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	299356.208
   Maximum:	329850.654
   Resolution:	0.0001

   Ellipsoid_Height

   WGS84 (Ellipsoid height) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	-43.927
   Maximum:	-26.307
   Resolution:	0.0001

   15BIM02_SBB_Level_03_1039_ITRF00.txt

   ASCII text file containing the processed single beam bathymetry x,y,z data in their native format of WGS84 (ITRF00) Ellipsoid height as acquired by the R/V Jabba Jaw (15BIM02). (Source: USGS)

   Shape

   Feature geometry (Source: Esri) Point ZM is the geometry type defining the feature

   ITRF00_Y

   WGS84 (ITRF00) Y-coordinate (northing) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	3275285.207
   Maximum:	3321903.262
   Resolution:	0.0001

   ITRF00_X

   WGS84 (ITRF00) X-coordinate (easting) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	299331.337
   Maximum:	329435.617
   Resolution:	0.0001

   Ellipsoid_Height

   WGS84 (Ellipsoid height) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	-41.598
   Maximum:	-26.677
   Resolution:	0.0001

   15BIM03_SBB_Level_03_1039_ITRF00.txt

   ASCII text file containing the processed single beam bathymetry x,y,z data in their native format of WGS84 (ITRF00) Ellipsoid height as acquired by the R/V Chum (15BIM03). (Source: USGS)

   Shape

   Feature geometry (Source: Esri) Point ZM is the geometry type defining the feature

   ITRF00_Y

   WGS84 (ITRF00) Y-coordinate (northing) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	3273754.345
   Maximum:	3326537.739
   Resolution:	0.0001

   ITRF00_X

   WGS84 (ITRF00) X-coordinate (easting) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	299346.579
   Maximum:	324561.398
   Resolution:	0.0001

   Ellipsoid_Height

   WGS84 (Ellipsoid height) of sample point, in meters. (Source: OPUS)

   Range of values
   Minimum:	-36.241
   Maximum:	-25.966
   Resolution:	0.0001

   15BIM01_SBB_Level_03_1039_NAD83_NAVD88_GEIOD12A.txt

   ASCII text file containing the processed single beam bathymetry x,y,z data in NAD83 NAVD88 Orthometric height as acquired by the R/V Sallenger (15BIM01). (Source: USGS)

   Shape

   Feature geometry (Source: Esri) Point ZM is the geometry type defining the feature

   NAD83_Y

   NAD83 (CORS96) Y-coordinate (northing) of sample point, in meters. (Source: VDatum Version 3.2)

   Range of values
   Minimum:	3270977.721
   Maximum:	333277.521
   Resolution:	0.0001

   NAD83_X

   NAD83 (CORS96) X-coordinate (easting) of sample point, in meters. (Source: VDatum Version 3.2)

   Range of values
   Minimum:	299356.971
   Maximum:	329851.412
   Resolution:	0.0001

   GEOID12A

   NAVD88 GEOID21A (Ortometric height) of sample point, in meters. (Source: VDatum Version 3.2)

   Range of values
   Minimum:	-15.576
   Maximum:	-0.109
   Resolution:	0.0001

   15BIM02_SBB_Level_03_1039_NAD83_NAVD88_GEIOD12A.txt

   ASCII text file containing the processed single beam bathymetry x,y,z data in NAD83 NAVD88 Orthometric height as acquired by the R/V Jabba Jaw (15BIM02). (Source: USGS)

   Shape

   Feature geometry (Source: Esri) Point ZM is the geometry type defining the feature

   NAD83_Y

   NAD83 (CORS96) Y-coordinate (northing) of sample point, in meters. (Source: VDatum version 3.2)

   Range of values
   Minimum:	3274284.631
   Maximum:	3321902.675
   Resolution:	0.0001

   NAD83_X

   NAD83 (CORS96) X-coordinate (easting) of sample point, in meters. (Source: VDatum version 3.2)

   Range of values
   Minimum:	299332.101
   Maximum:	329436.376
   Resolution:	0.0001

   NAVD88_GEIOD12A

   NAVD88 GEIOD12A (Orthometric height) of sample point, in meters. (Source: VDatum version 3.2)

   Range of values
   Minimum:	-13.764
   Maximum:	0.0001
   Resolution:	0.0001

   15BIM03_SBB_Level_03_1039_NAD83_NAVD88_GEIOD12A.txt

   ASCII text file containing the processed single beam bathymetry x,y,z data in NAD83 NAVD88 Orthometric height as acquired by the R/V Chum (15BIM03). (Source: USGS)

   Shape

   Feature geometry (Source: Esri) Point ZM is the geometry type defining the feature

   NAD83_Y

   NAD83 (CORS96) Y-coordinate (northing) of sample point, in meters. (Source: VDatum version 3.2)

   Range of values
   Minimum:	3273753.770
   Maximum:	3326537.151
   Resolution:	0.0001

   NAD83_X

   NAD83 (CORS96) X-coordinate (easting) of sample point, in meters. (Source: VDatum version 3.2)

   Range of values
   Minimum:	299347.343
   Maximum:	324562.158
   Resolution:	0.0001

   NAVD88_GEIOD12A

   NAVD88 GEIOD12A (Orthometric height) of sample point, in meters. (Source: VDatum version 3.2)

   Range of values
   Minimum:	-9.343
   Maximum:	0.000
   Resolution:	0.0001

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 (SPCMSC).

3. To whom should users address questions about the data?
   Chelsea A. Stalk

   Cherokee Nation Technologies/U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center

   Researcher I

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727)502-8000 (voice)

   cstalk@usgs.gov

Why was the data set created?

This zip archive contains processed x,y,z data points for all single beam bathymetry data collected under the FAN 2015-317-FA, which encompasses data from three separate survey platforms; the R/V Sallenger (15BIM01), R/V Jabba Jaw (15BIM02), and R/V Chum (15BIM03), all part of the June 2015 Chandeleur Islands survey. The processed single beam bathymetry data are provided as an ASCII x,y,z point data file.

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: 2015 (process 1 of 7)

   Three Geographic Positioning Systems (GPS) base stations were occupied during this survey (http://pubs.usgs.gov/ds/01039/html/ds1039_ overview.html). Benchmark MRK3 was located in the northern part of the survey area on the sound side of the islands near the Pelican fishing camp, SM01 was located in the middle of the survey area in the middle of the island at Monkey Bayou, and GRIG was located in the southern end of the survey on an abandoned oil drilling platform. The base stations were equipped with Ashtech Proflex GPS Receivers recording 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via Thales Choke-ring antennas, recording at a rate of 0.1 seconds (s). Person who carried out this activity:
   

   Chelsea A. Stalk

   Cherokee Nation Technologies/U.S. Geological Survey's St. Petersburg Coastal and Marine Science Center

   Researcher I

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   cstalk@usgs.gov

   Date: 2015 (process 2 of 7)

   Single Beam Bathymetry Acquisition: The single beam bathymetric data were collected under the USGS FAN 2015-317-FA, which encompasses three sub-cruise identifiers specific to platform (15BIM01, 15BIM02, 15BIM03). Data were collected aboard three separate survey platforms: the 26-foot (ft) R/V Sallenger (cruise identifier 15BIM01), the the 17ft R/V Jabba Jaw (15BIM02), and the Personal Water Craft (PWC) R/V Chum (15BIM03), for a total of 1,614 trackline km. In total, the survey is approximately 2,400 km2, extending 3 km from the back-barrier shoreline of the islands and 5 km from the Gulf of Mexico shoreface. Shore-perpendicular survey lines were spaced approximately 500 m apart and shore-parallel crossing lines were located as close to the shoreline as possible, 1 km from the shoreline, and 3 km offshore of the Gulf shoreline. All data were collected and processed in the World Geodetic System 1984 (WGS1984 G1150). Boat motion was recorded at 50-millisecond (ms) intervals using a Teledyne TSS Dynamic Motion Sensor (TSS DMS-05) only on vessels 15BIM01 and 15BIM02. A motion sensor devise was not used for the PWC (15BIM03). Rather, to minimize motion errors, R/V Chum recorded GPS at a rapid rate of 0.1 s, utilized a short antenna height by use of a lever arm, and was outfitted with a narrow (4 degree) transducer beam. HYPACK version 14.0.9.47 (15BIM01, 15BIM02) version 13.0.09.17 (15BIM03), managed the planned-transect information and provided real-time navigation, steering, correction, data quality, and instrumentation status information to the boat operator. Depth soundings were recorded at 50-ms intervals using an Odom echotrac CV100 sounder with a 200-kilohertz (kHz) transducer. Data from the GPS receiver, motion sensor, and fathometer were recorded in real-time aboard all vessels independently and merged into a single raw data file (.raw) in HYPACK, with each device string referenced by a device identification code and time stamped to UTC. Sound velocity profile (SVP) measurements were collected using two SonTek CastAway Conductivity, Temperature, and Depth (CTD) instruments as well as a Valport mini sound velocity profiler (SVP). The instruments were periodically cast overboard to observe changes in speed of sound (SOS). A total of 188 successful sound velocity casts were taken throughout the survey. Casts were taken at an average depth of 4.01 m, ranging from 0.13 m to 13.96 m and recorded an average sound velocity of 1527.93 meters per second (m/s) ranging from 1519.85 to 1539.23 m/s. The recorded profiles were later incorporated into the post-processing software to correct the depth for temporal and spatial SOS changes throughout the water column. Person who carried out this activity:
   

   Chelsea A. Stalk

   Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center

   Researcher I

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   cstalk@usgs.gov

   Data sources produced in this process:

   • HYPACK raw (*.RAW) data files for each trackline surveyed. HYPACK target files for any targets (*.TGT) recorded digitally while surveying, speed of sound files (*.TXT) in text format.

   Date: 2015 (process 3 of 7)

   Differentially Corrected Navigation Processing: The coordinate values of the GPS base stations (MRK3, SM01, GRIG) are the time-weighted average of values obtained from OPUS. The base station coordinates were imported into GrafNav version 8.5 (Waypoint Product Group) and the kinematic GPS data from the survey vessel were post processed to the concurrent GPS session data at the base stations. During processing, steps were taken to ensure that the trajectories between the base and the rover were clean, resulting in fixed positions. By analyzing the graphs, trajectory maps, and processing logs that GrafNav produces for each GPS session, GPS data from satellites flagged by the program as having poor health or satellite time segments that had cycle slips were excluded, or the satellite elevation mask angle was adjusted to improve the position solutions. The final differentially corrected, precise DGPS positions were computed at the respective time intervals of the roving GPS (1.0 s for 15BIM01 (JD 168-171), 0.2 s for 15BIM01 (JD 172-175) and 15BIM02, and 0.1 s for 15BIM03) and exported in ASCII text format to replace the uncorrected rover positions recorded during acquisition. The GPS data were processed and exported in the World Geodetic System of 1984 (WGS84 G1150) geodetic datum. Person who carried out this activity:
   

   Cherokee Nation Technologies/U.S. Geological Survey

   Attn: Chelsea A. Stalk

   Researcher I

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   cstalk@usgs.gov

   Data sources produced in this process:

   • Post-processed differential navigation data for the rover (boat) were exported in ASCII text format. Three files (forward, reverse, and combined trajectories) are produced for each GPS session file.

   Date: 2015 (process 4 of 7)

   Single Bream Processing: The raw HYPACK® data files were imported into CARIS HIPS and SIPS® (Hydrographic Information Processing System and Sonar Information Processing System) version 9.0.17. The corrected DGPS positions exported from GrafNav were imported into CARIS using the generic data parser tool. After parsing, the navigation data were scanned using the Navigation Editor, which allows the user to view multiple types of plots including trackline orientation, timing, and course direction. This check verifies if the parsed data corresponds to the processed DGPS. Next, Speed of Sound (SOS) Profile (SVP) casts were entered, and edited, using the SVP editor tool, and then applied as nearest in distance within time. All soundings are referenced to the ellipsoid (WGS84, ITRF00) during processing, this involved a step in CARIS to compute the GPS tide. The GPS tide represents the ellipsoidal surface. GPS tide and GPS height are then compared against each other to ensure correct computation by the program and applied GPS antenna height provided in the vessel file. All bathymetric data components; position, motion, depth, GPS tide, and Speed of Sound (SOS), were then merged and geometrically corrected in CARIS to produce processed x,y,z data. Once merged the dataset is reviewed for erroneous points using the Single Beam Editor. The points that are visually obvious outliers are often related to cavitation in the water column obscuring the fathometer signal, tight turns in the surf zone affecting the tracking of the incoming GPS signal, and/or false readings due to general equipment issues. Data showing these are either discarded or adjusted to surrounding sounding depths. Also, data points in areas of extremely shallow water (0.30 m to 0.50 m) such as shoals and seagrass beds are reviewed against the surrounding data for overall consistency. Finally, a Bathymetry with Associated Statistical Error (BASE) surface is created. Using the Subset Editor, the BASE surface is used as a color coded guide to pinpoint crossings that are visually offset from one another. If an offset is identified, it is further examined and is reprocessed if necessary. The geometrically-corrected point data are then exported as an x,y,z ASCII text file referenced to WGS84 (G1150), equivalent to ITRF00, UTM 16, and ellipsoid height in meters. The single beam bathymetry datasets combined (15BIM01, 15BIM02, and 15BIM03) consists of 8,223,749 point elevations with an ellipsoidal elevation range of -43.927 to -25.097 m. Person who carried out this activity:
   

   Cherokee Nation Technologies/U.S. Geological Survey

   Attn: Chelsea A. Stalk

   Researcher I

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   cstalk@usgs.gov

   Data sources used in this process:

   • Post-processed differential navigation data, raw HYPACK bathymetric data, and sound velocity data all in ASCII text format.

   Data sources produced in this process:

   • 15BIM01_SBB_Level_02_1039_ITRF00.txt 15BIM02_SBB_Level_02_1039_ITRF00.txt 15BIM03_SBB_Level_02_1039_ITRF00.txt

   Date: 2015 (process 5 of 7)

   Quality Control and Quality Assurance (QA/QC) and Datum transformation: All single beam data found in the ASCII exported from CARIS were imported into Esri ArcMap version 10.2, where a shapefile of the individual data points (x,y,z) was created and plotted in 1-m color coded intervals. First, all data were visually scanned for any obvious outliers or problems. A Python script was used for the purpose of evaluating elevation differences at the intersection of crossing tracklines by calculating the elevation difference between points at each intersection using an inverse distance weighting equation. GPS cycle slips, stormy weather conditions, and rough sea surface states can contribute to poor data quality. If discrepancies that exceed the acceptable error threshold were found, then the line in error was either removed or statically adjusted by the average of the crossings within the line. The script was run on all vessel point data first on a vessel by vessel basis and then run a final time for all data points from all vessels collectively. For this dataset, the collective run, using a merged shapefile of all vessel point data, is the most important as the survey structure did not allow for sufficient vessel crossing, rather vessels crossing other vessels. Once the dataset passed all QA/QC procedures and manual editing steps, the data were considered final. Person who carried out this activity:
   

   Cherokee Nation Technologies/U.S. Geological Survey

   Attn: Chelsea A. Stalk

   Researcher I

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   cstalk@usgs.gov

   Data sources used in this process:

   • 15BIM01_SBB_Level_02_1039_ITRF00.txt 15BIM02_SBB_Level_02_1039_ITRF00.txt 15BIM03_SBB_Level_02_1039_ITRF00.txt

   Data sources produced in this process:

   • 15BIM01_SBB_Level_03_1039_ITRF00.txt 15BIM02_SBB_Level_03_1039_ITRF00.txt 15BIM03_SBB_Level_03_1039_ITRF00.txt

   Date: 2015 (process 6 of 7)

   Datum Transformation: The text files,15BIM01_SBB_Level_03_1039_ITRF00.txt,15BIM02_SBB_Level_03_1039_ITRF00.txt,15BIM03_SBB_Level_03_1039_ITRF00.txt, were converted using the National Oceanic and Atmospheric Association (NOAA) VDatum software conversion tool version 3.2 (reported vertical transformation error is 5.4 cm) from the International Terrestrial Reference Frame of 2000 (ITRF00) to the North American Datum of 1983 (NAD83) reference frame and the North American Vertical Datum of 1988 (NAVD88) orthometric height using the National Geodetic Survey (NGS) geoid model of 2012 (GEOID12A). Person who carried out this activity:
   

   Chelsea A. Stalk

   Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center

   Researcher I

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   cstalk@usgs.gov

   Data sources used in this process:

   • 15BIM01_SBB_Level_03_1039_ITRF00.txt 15BIM02_SBB_Level_03_1039_ITRF00.txt 15BIM03_SBB_Level_03_1039_ITRF00.txt

   Data sources produced in this process:

   • 15BIM01_SBB_Level_03_1039_NAD83_NAVD88_Geoid12A.txt 15BIM02_SBB_Level_03_1039_NAD83_NAVD88_Geoid12A.txt 15BIM03_SBB_Level_03_1039_NAD83_NAVD88_Geoid12A.txt

   Date: 13-Oct-2020 (process 7 of 7)

   Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: VeeAnn A. Cross

   Marine Geologist

   384 Woods Hole Road

   Woods Hole, MA
   

   508-548-8700 x2251 (voice)

   508-457-2310 (FAX)

   vatnipp@usgs.gov

3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?
   The accuracy of the data is determined during data collection. This dataset is from one research cruise and is therefore internally consistent. Methods are employed to maintain data collection consistency aboard all platforms (15BIM01, 15BIM02, 15BIM03). 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 and entered into their respective programs for calibration. Once calibration is complete and calibration status is considered acceptable, then survey operations commence. The single beam systems on each survey platform have a dedicated computer, and efforts are made to utilize the same equipment and software versions for each system and platform. However, upgrades and changes occur and require additional setup, measurements, and notation. For the single beam bathymetry, offsets between the single beam transducers and the Ashtech antenna reference point (ARP) were measured and accounted for in post-processing. Bar checks were performed as a calibration check and helped to correct any drift in the echosounder. Differential Global Positioning System (DGPS) coordinates were obtained using post-processing software packages (National Geodetic Survey On-Line Positioning User Service, OPUS, and Waypoint Product Group GrafNav, version 8.5.
2. How accurate are the geographic locations?
   All static base station sessions were processed through the On-Line Positioning User Service (OPUS) maintained by the National Oceanic and Atmospheric Administration (NOAA) and the National Geodetic Survey (NGS). The base location results from OPUS were entered into a spreadsheet to compute a final, time-weighted positional coordinate (latitude, longitude, and ellipsoid height). Base station positional error for each GPS session was calculated as the absolute value of the final position minus the session position value. The maximum horizontal error of the base station coordinates used for post-processing the single beam bathymetry was 0.01992 seconds latitude and 0.26566 seconds longitude for the USGS benchmark, MRK3, 0.01280 seconds latitude and 0.00021 seconds longitude for SM01, and 0.00063 seconds latitude and 0.00064 seconds longitude for GRIG (http://pubs.usgs.gov/ds/01039/html/ds1039_ overview.html).
3. How accurate are the heights or depths?
   All static base station sessions for MRK3, SM01, and GRIG were processed through OPUS. The base location results from OPUS were entered into a spreadsheet to compute a final, time-weighted positional coordinate (latitude, longitude, and ellipsoid height). Base station positional error for each GPS session was calculated as the absolute value of the final position minus the session position value. SPCMSC standards define the maximum acceptable vertical error for any individual base station GPS session as less than or equal to three times the standard deviation of the ellipsoid height; any occupations exceeding this error are removed and the base station coordinates are recalculated. For the MRK3 base station location, the standard deviation of the ellipsoid height was 0.0037 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.025 m. For the SM01 base station location, the standard deviation of the ellipsoid height was 0.0035 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.009 m. For the GRIG base station location, the standard deviation of the ellipsoid height was 0.0075 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.013m. All the processed single beam bathymetry data (x,y,z) for 2015 are referenced to these base station coordinates, which are in ITRF00. The differentially corrected navigation files (base station GPS processed to boat GPS) were exported from GrafNav version 8.5 and then imported into CARIS HIPS and SIPS version 9.0.17 and merged, by time, with the HYPACK (version 14.0.9.47 for 15BIM01, 15BIM02 and version 13.0.09.17 for 15BIM03) raw data files at which point the soundings are then geometrically corrected for motion and speed of sound.
4. Where are the gaps in the data? What is missing?
   These are complete post-processed x,y,z bathymetric data points from acoustic single beam bathymetry data collected in June 2015 in the nearshore of the Chandeleur Islands, Louisiana.
5. How consistent are the relationships among the observations, including topology?
   This file represents the post-processed bathymetric data (x,y,z) collected during one single beam bathymetry (SBB) survey, FAN 2015-317-FA, which includes data from three separate survey platforms R/V Sallenger (15BIM01), R/V Jabba Jaw (15BIM02), and R/V Chum (15BIM03). Refer to the online Data Series linkage for field logs, vessel platform descriptions, and other survey information; this is directly available at http://pubs.usgs.gov/ds/1039/ds-logs.

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)
   
   Chelsea A. Stalk

   Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center

   Researcher I

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   cstalk@usgs.gov
2. What's the catalog number I need to order this data set? 15BIM01_SBB_Level_03_1039_NAD83_NAVD88_Geoid12A.txt,15BIM02_SBB_Level_03_1039_NAD83_NAVD88_Geoid12A.txt,15BIM03_SBB_Level_03_1039_NAD83_NAVD88_Geoid12A.txt,15BIM01_SBB_Level_03_1039_ITRF00.txt,15BIM02_SBB_Level_03_1039_ITRF00.txt,15BIM03_SBB_Level_03_1039_ITRF00.txt
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?
   • Availability in digital form:

     Data format:	ASCII Size: 26.0
     Network links:	https://pubs.usgs.gov/ds/1039/downloads/ASCII/15BIM01_SBB_XYZ.zip https://pubs.usgs.gov/ds/1039/downloads/ASCII/15BIM02_SBB_XYZ.zip https://pubs.usgs.gov/ds/1039/downloads/ASCII/15BIM03_SBB_XYZ.zip

   • Cost to order the data: none

5. What hardware or software do I need in order to use the data set?

   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:

Chelsea A. Stalk

Cherokee Nation Technologies/U.S. Geological Survey St. Petersburg Coastal and Marine Science Center

Researcher I

600 4th Street South

St. Petersburg, FL

USA

(727) 502-8000 (voice)

cstalk@usgs.gov

Metadata standard:

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