Attribute_Accuracy_Report:
The accuracy of the data is determined during data collection. The SBB data were collected during one research effort in July, 2016, USGS FAN 2015-347-FA, subFANs 16BIM05 and 16BIM06. This dataset utilized two vessels and is therefore internally consistent per platform. Methods were employed to maintain data collection consistency aboard each platform. During mobilization, each piece of equipment is isolated to obtain internal and external offset measurements with respect to the survey platform. Each system has a dedicated computer, and efforts are made to utilize the same equipment and software versions on all systems. However, upgrades and changes occur and require additional setup, measurements, and notation. DGPS was always implemented for navigational accuracy in post-processing. These bathymetric data have not been independently verified for accuracy.
For the SBB, offsets between the single-beam transducers, the Ashtech antenna reference point (ARP), and the vessel motion units were measured and accounted for on all platforms. All pertinent measurements were accounted for in the DGPS post-processing software packages (National Geodetic Survey On-Line Positioning User Service (OPUS), and Waypoint Product Group GrafNav, version 8.6).
This file consists of the post-processed bathymetric data (x,y,z) (subFANs 16BIM05, 16BIM06) and represents data coverage for the single-beam portion of the the 2016 nearshore survey (USGS FAN 2015-347-FA) from Ship Island to Horn Island, GUIS, Mississippi. Refer to the supplemental information section of the data release for field logs, vessel platform descriptions, and other survey information.
These are complete post-processed x,y,z bathymetric data points from acoustic single-beam data collected in July 2016 from the nearshore areas of Ship Island to Horn Island, Mississippi.
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Three benchmark locations were occupied, two on Horn Island and one on Ship Island. On Horn Island, the first benchmark, 202Q 1998 (USACE) was located at the ranger station's trail head south of the pier. The second benchmark WHRN (USGS SPCMSC) was located on the western end of Horn Island atop short sand ridge, on the sound side of the island. The Ship Island benchmark PID BBCL83, stamping 4756 F 2011 (John Oswald and Associates, LLC) was located on the north side of the intersection where the main boardwalk meets the generator shed boardwalk. All the static GPS base station sessions were using 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 one final coordinate and error analysis for that base location. Using the OPUS values for each day, and the total time per GPS session, the average weighted value of occupation time was calculated so the longer occupations hold more value than shorter occupations. The final value for latitude, longitude, and ellipsoid height was the weighted average of each GPS session processed with OPUS. This value was entered into GrafNav version 8.6 as the base station coordinates. The range from the average values was calculated, using outputs from OPUS, for each session as the absolute value of the final value minus the daily value. The maximum horizontal range of the base station coordinates used for post-processing the single-beam bathymetry was 0.00026 decimal seconds latitude and 0.00049 decimal seconds longitude for 202Q, 0.00038 decimal seconds latitude and 0.00033 decimal seconds longitude for WHRN. The reported error for 4756 F 2011 is 0.013 meters latitude and 0.012 meters longitude.
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 0.00038
Horizontal_Positional_Accuracy_Explanation:
The range of error for base stations 202Q and WHRN is 0.00026 - 0.00038 latitude decimal seconds. The datasheet for 4756 F 2011 reports the latitude in Degrees, Minutes, decimal Seconds (DMSss) with an error of +/-0.012 m.
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 0.00049
Horizontal_Positional_Accuracy_Explanation:
The range of error for base stations 202Q and WHRN is 0.00033 - 0.00049 longitude decimal seconds. The datasheet for 4756 F 2011 reports the longituded in Degrees, Minutes, decimal Seconds (DMSss) with an error of +/-0.012 m.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
All static base station sessions for 202Q and WHRN were processed through 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 position 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 then recalculated and considered final. For 202Q base location, the standard deviation of the ellipsoid height was 0.010 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.023 m. For WHRN base location, the standard deviation of the ellipsoid height was 0.002 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.022 m. For the 4756 F 2011 base station only one OPUS session was run so the published coordinates were used. The survey datasheet reports the vertical error of the ellipsoid height as +/- 0.017 m.
Process_Step:
Process_Description:
GPS Acquisition: Three benchmark locations were occupied, two on Horn Island and one on Ship Island. On Horn Island, the first benchmark, 202Q 1998 (USACE) was located at the ranger station's trail head south of the pier. The second benchmark WHRN (USGS SPCMSC) was located on the western end of Horn Island atop short sand ridge, on the sound side of the island. The Ship Island benchmark PID BBCL83, stamping 4756 F 2011 (John Oswald and Associates, LLC) was located on the north side of the intersection where the main boardwalk meets the generator shed boardwalk. Each base was equipped with an Ashtech ProFlex GPS receiver, which recorded the 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via the Thales choke-ring antenna at a rate of 2 times per second. GPS instrumentation was duplicated on all single-beam survey vessels (rovers), which recorded concurrently at 2 times per second. The GPS navigation data were acquired and processed in WGS84 (G1150).
Process_Date: 2016
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Nancy T. DeWitt
Contact_Organization:
U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: ndewitt@usgs.gov
Process_Step:
Process_Description:
Single-Beam Bathymetry Acquisition: Depth soundings were acquired aboard all vessels at 100-milliseconds (ms) using an Odom CV100 echo sounder system with a 200 kilohertz (kHz) transducer. Boat motion was recorded on the R/V Jabba Jaw (16BIM05) using an SBG Ellipse A motion sensor, and the R/V Mako (16BIM06) using a TSS Dynamic Motion Sensor (TSS DMS-05). All sensor data were combined and saved into a single raw data file (.raw) in HYPACK version 15.0.9.71, with each device string referenced by a device identification code and time stamped to Coordinated Universal Time (UTC). Sound velocity measurements were collected using Sontek Castaway CTD units to record changes in water column speed of sound (SOS).
Process_Date: 2016
Source_Produced_Citation_Abbreviation:
HYPACK raw data files (.raw), HYPACK target files (.tgt), and SVP files (.txt, *.csv, *.svp).
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Nancy T. DeWitt
Contact_Organization:
U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: ndewitt@usgs.gov
Process_Step:
Process_Description:
Differentially corrected navigation processing: The coordinate values for each of the GPS base stations (202Q, and WHRN) are the time-weighted average of values obtained from the National Geodetic Survey's (NGS) On-Line Positioning User Service (OPUS). Because there was only one session for benchmark 4756 F 2011, the published coordinates were used. The coordinates were imported into the post-processing software GrafNav (Waypoint Product Group) version 8.6. For post-processing, the kinematic GPS data from the survey vessels were processed to the concurrent GPS data from the closest base stations. Steps were taken to ensure that the trajectories between the base and rover were clean and resulted in fixed positions. GPS data quality could be monitored and manipulated by analyzing the graphs, trajectory maps, and processing logs that GrafNav produces for each GPS session. If poor GPS data were identified, some common tools used to improve the solution were utilized. These options included, but were not limited to, omitting a satellite flagged as poor in health, excluding time-segments with cycle slips, or adjusting the satellite elevation mask angle. The final, differentially-corrected, precise DGPS positions were computed at each roving vessels respective recording rate, and then exported in ASCII text format. The exported ASCII file then replaced the uncorrected real-time rover positions recorded during acquisition later in processing. The GPS data were processed and exported in the WGS84 (G1150) geodetic datum.
Process_Date: 2016
Source_Produced_Citation_Abbreviation:
Post-processed differential navigation data for the rover (boat) in ASCII text format.
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Nancy T. DeWitt
Contact_Organization:
U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: ndewitt@usgs.gov
Process_Step:
Process_Description:
Single-beam bathymetry processing: All data were processed using CARIS HIPS and SIPS (Hydrographic Information Processing System and Sonar Information Processing System) version 9.1. The raw HYPACK data files were imported into CARIS where the differentially corrected navigation files were imported using the generic data parser tool within CARIS, and any SVP profile casts were applied. The bathymetric data components (position, motion, depth, and SOS) were then merged and geometrically corrected to produce processed x,y,z data. Next, the data were edited for outliers and then further reviewed in the Subset Editor utility for crossing status, and questionable data points or areas. The geometrically corrected point data were then exported as an x,y,z ASCII text file referenced to WGS84 (G1150), equivalent to ITRF00, and ellipsoid height in meters. The exported ASCII files from each vessel were then combined into one file for further quality assurance and quality control.
Source_Used_Citation_Abbreviation:
Post-processed differential navigation data files (*.txt), HYPACK RAW bathymetric data files (*.RAW), HYPACK target (.tgt) files, and SVP files (.txt, *.csv, *.svp) files all in ASCII text format.
Process_Date: 2016
Source_Produced_Citation_Abbreviation:
16BIM05_SBB_Level_03_ITRF00.txt
16BIM06_SBB_Level_03_ITRF00.txt
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Nancy T. DeWitt
Contact_Organization:
U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: ndewitt@usgs.gov
Process_Step:
Process_Description:
Single-beam bathymetry error analysis: The ASCII files described in the previous step were imported into ArcMap version 10.3 and reviewed for outliers. An Esri ArcMap add-in program script was written locally, by USGS staff to evaluate the elevation differences at the intersection of crossing lines. If discrepancies were found at a crossing, the source of the discrepancies was identified and, if needed, the line or segment of data points in error was statically adjusted or removed. This process was reiterated again to produce a final assessment of the crossing range for the SBB dataset.
Source_Used_Citation_Abbreviation:
16BIM05_SBB_Level_03_ITRF00.txt
16BIM06_SBB_Level_03_ITRF00.txt
Process_Date: 2016
Source_Produced_Citation_Abbreviation:
16BIM05_SBB_Level_03_ITRF00_lines_removed_draft1a.txt
16BIM06_SBB_Level_03_ITRF00.txt
Ship_Horn_2016_SBB_ITRF00_xyz.txt
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Nancy T. DeWitt
Contact_Organization:
U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: ndewitt@usgs.gov
Process_Step:
Process_Description:
VDatum version 3.6 transformation: The SBB data were transformed two times, using VDatum. The vertical transformation errors reported by VDatum are the following: 1) Transformation from ITRF00 to NAD83, NAVD88 with respect to GEOID12B is 0.0762 m or 7.62 cm for the vertical area named GEOID12B; and 2) Transformation from NAD83, NAVD88 with respect to GEOID12B to NAD83, MLLW is 0.163 m or 16.30 cm for the vertical area named LAmobile02-8301.
Source_Used_Citation_Abbreviation:
16BIM05_SBB_Level_03_ITRF00_lines_removed_draft1a.txt
16BIM06_SBB_Level_03_ITRF00.txt
Process_Date: 2016
Source_Produced_Citation_Abbreviation:
Ship_Horn_Island_2016_SBB_NAD83_NAVD88_GEOID12B_xyz.txt
Ship_Horn_Island_2016_SBB_NAD83_MLLW_xyz.txt
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Nancy T. DeWitt
Contact_Position: Geologist
Contact_Address:
Address_Type: Mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: U.S.
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: ndewitt@usgs.gov
Process_Step:
Process_Description:
The trackline files were created separately for 16BIM05 and 16BIM06 from the x,y,z point files in Esri ArcGIS version 10.3 using the XTools Pro extension, version 11.1. Using the "XTools" feature conversion tool, "make polylines from points" the x,y,z data point shapefile was converted into a polyline shapefile. This was repeated for each vessel. Both resultant polyline shapefiles were then merged into one file for the data release and projected in NAD83 Universal Transverse Mercator (UTM) Zone 16 North.
Source_Used_Citation_Abbreviation:
16BIM05_SBB_Level_003_xxx_ITRF00_tracklines_lines_removed_forDraft1a.shp
16BIM06_SBB_Level_003_xxx_ITRF00_tracklines.shp
Process_Date: 2016
Source_Produced_Citation_Abbreviation:
Ship_Horn_Island_2016_SBB_ITRF00_tracklines.shp
Ship_Horn_Island_2016_SBB_NAD83_tracklines.shp
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Nancy T. DeWitt
Contact_Position: Geologist
Contact_Address:
Address_Type: Mailing and physical
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Contact_Voice_Telephone: (727) 502-8000
Contact_Electronic_Mail_Address: ndewitt@usgs.gov
Process_Step:
Process_Description:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20201013
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
