Attribute_Accuracy_Report:
The accuracy of the data is determined during data collection. The SBB data were collected during concurrent research cruises in July and August, 2013. This dataset is from one research cruise and is therefore internally consistent. Methods were employed to maintain data collection consistency aboard the 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 both systems. However, upgrades and changes occur and require additional setup, measurements, and notation. DGPS was always implemented for navigational accuracy either during acquisition as RTK or as a post-processing step. 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 TSS motion unit were measured and accounted for on the rovers. For RTK in July (13BIM03 and 13BIm04) all respective base station parameters and rover parameters including antenna height and antenna models were entered into their respective GPS units. For the August surveys, 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 8.3). Bar checks were also performed as calibration efforts and accounted for any drift in the echosounder.
This file represents the post-processed bathymetric data (x,y,z) collected during SBB surveys. They represent data coverage for the single-beam portion of the 2013 Chandeleur survey, specifically FAN 13BIM03, 13BIM04, and 13BIM08. Refer to the online data series linkage for field logs, vessel platform descriptions, and other survey information; this information is directly available at
https://doi.org/10.3133/ds1032
These are complete post-processed xyz bathymetric data points from acoustic single-beam data collected in July and August 2013 from the northern Chandeleur Islands.
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
All static GPS base station sessions were run 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 one final coordinate and error analysis for that base location. Using the OPUS values for each day, and the total time that data were collected each day, the average daily weighted value of occupation time was calculated; longer occupation times held more value than shorter times. The final value for latitude, longitude, and ellipsoid was the weighted average of all the GPS session processed with OPUS. This value was entered in GrafNav version 8.1 as the base station coordinates. Error was calculated using output from OPUS for each day and was calculated as the absolute value of the final value minus the daily value. The maximum horizontal error of the base station coordinates used for post-processing the single-beam bathymetry was 0.00042 decimal seconds latitude and 0.00096 decimal seconds longitude for TMRK and 0.00015 decimal seconds latitude and 0.00030 decimal seconds longitude for BRM2.
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 0.00000 - 0.00042
Horizontal_Positional_Accuracy_Explanation: latitude decimal seconds
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 0.00001 - 0.00096
Horizontal_Positional_Accuracy_Explanation: longitude decimal seconds
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
All static base station sessions for TMRK and BRM2 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 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 3 times the standard deviation of the ellipsoid height; any occupations exceeding this error are removed and the base station coordinates are recalculated. For TMRK base location the standard deviation of the ellipsoid height was 0.014 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.030 m. For BRM2 base location the standard deviation of the ellipsoid height was 0.013 m and the maximum difference from the average ellipsoid for any GPS session was +/- 0.031 m.
All the RTK and the post-processed SBB data (x,y,z) for 2013 are referenced to these base station coordinates. The differentially corrected navigation files (base station GPS processed to boat GPS) were exported from GrafNav version 8.4 and then imported into CARIS HIPS and SIPS version 7.1 and merged by time with the HYPACK (version 10.0.5.31) raw data files at which point the soundings are then geometrically corrected for motion and speed of sound. For the single-beam soundings, elevation differences at 320 crossings were within +/- 0.15 m which accounts for 68 percent of the crossings.
Process_Step:
Process_Description:
GPS Base Station Acquisition: A GPS base station was erected at a temporarily installed USGS benchmark (TMRK) located on the sound side of the Chandeleur Islands. A second base station (BRM2) was erected on the furthest northern island providing differential GPS coverage for the survey area within a 15 km radius of either benchmark. GPS receivers recorded the 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via the Thales choke-ring antenna at the base stations. This GPS instrument combination was duplicated on the single-beam survey vessel (rover).
The SBB data was acquired using RTK for 13BIM03 and 13BIM04 in July. Both base stations were equipped with a Magellan ProFlex500 GPS receiver, a Thales choke ring antenna, a Pacific Crest ADLP-1 390-430 megahertz (MHz) radio, and a Pacific Crest 5 decibel (dB) high power radio whip antenna. The radio whip antennas were placed onto 10-m collapsible masts providing line of site transmission to the vessels (rovers). The GPS and radio components were duplicated on each vessel. The base stations were set to record internally at a rate greater than or equal to the recording rate of the rovers, in this case 5 Hz. The known coordinates of each base station were entered into the GPS receiver and the RTK corrections were broadcast to the roving GPS receivers via the radio links at 5 Hz. The R/V Jabba Jaw recorded GPS positions at 1 Hz using an Ashtech Z-Xtreme GPS receiver and Thales choke ring antenna. The R/V Shark recorded GPS positions at a rate of 5 Hz using a Magellan ProFlex 800 GPS receiver and Ashtech marine antenna (table 2).
For the August SBB survey (13BIM03) RTK was not used to collect SBB data and all navigation was post-processed to obtain DGPS. The base receivers and the rover receiver recorded their positions concurrently at 1-second (s) intervals throughout the survey. GPS data was acquired and processed in the World Geodetic Datum of 1984 (WGS84) (G1150).
Process_Date: 2013
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 the R/V Jabba Jaw and the R/V Shark at 100-milliseconds (ms) using an Odom CV100 echosounder system with a 200 kilohertz (kHz) transducer. Boat motion was recorded on the R/V Jabba Jaw at 50-ms intervals using a Teledyne TSS Dynamic Motion Sensor (TSS DMS-05). The R/V Shark did not record boat motion. To minimize motion errors, the R/V Shark recorded GPS at a high rate (5 Hz) and utilized a short antenna height (lever-arm) in combination with a narrow (4 degree) transducer beam. All sensor data were saved into a single raw data file (.raw) in HYPACK, with each device string referenced by a device identification code and time stamped to Coordinated Universal Time (UTC). Sound velocity measurements were collected using a Valeport mini Sound Velocity Profiler (SVP) to observe changes in water column speed of sound (SOS).
Process_Date: 2013
Source_Produced_Citation_Abbreviation:
HYPACK raw data files (.RAW), HYPACK target files (.TGT), and SOS files (.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:
Differentially Corrected Navigation Processing: The coordinate values for each of the GPS base stations (TMRK and BRM2) are the time-weighted average of values obtained from the National Geodetic Survey's (NGS) On-Line Positioning User Service (OPUS). Depending on the survey design, the coordinates were utilized either during acquisition to provide RTK navigation, or imported into the post-processing software GrafNav (Waypoint Product Group). For post processing, the kinematic GPS data from the survey vessels were processed to the concurrent GPS data from the 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 was identified, some common tools used to improve the solution 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 1-second (s) intervals for each roving GPS session, and then exported in American Standard Code for Information Interchange (ASCII) text format, which replaced the uncorrected real-time rover positions recorded during acquisition. The GPS data were processed and exported in the World Geodetic System of 1984 (WGS84) (G1150) geodetic datum.
For USGS cruises 13BIM03 and 13BIM04, RTK navigation was implemented. The OPUS derived base station coordinates were programed into their respective base station GPS receivers and position corrections were broadcasted via radio link to the roving GPS receivers located on each survey vessel. However, 13BIM04 was ultimately post-processed using GrafNav version 8.50 after identification of some unreliable navigation segments. RTK was not implemented during cruise 13BIM08 so navigation data was post-processed using GrafNav version 8.4 and all pertinent base information details were accounted during processing.
Process_Date: 2013
Source_Produced_Citation_Abbreviation:
Post-processed differential navigation data for the rover (boat) in ASCII text format. 3 files (forward, reverse, and combined trajectories) are produced for each GPS session file.
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 8.1.5. The raw HYPACK (version 10) data files were imported into CARIS, the differentially corrected navigation files were imported using the generic data parser tool within CARIS, and any SVP profile casts were entered and edited using the SVP editor within CARIS. The bathymetric data components (position, motion, depth, and SOS) were then merged and geometrically corrected in CARIS 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.
Source_Used_Citation_Abbreviation:
Post-processed differential navigation data files, HYPACK RAW bathymetric data files, HYPACK target (.TGT) files, and SOS (.txt) files all in ASCII text format.
Process_Date: 2013
Source_Produced_Citation_Abbreviation:
13BIM03_SBB_03_ITRF00_xxx.txt
13BIM04_SBB_03_ITRF00_xxx.txt
13BIM08_SBB_03_ITRF00_xxx.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 data were edited for outliers in the Single-Beam Editor of CARIS and then 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), which is equivalent to ITRF00, and ellipsoid height in meters. This ASCII file was then imported into ArcMap version 10.1 and reviewed for outliers. An Esri ArcMap Ad-In program script was written locally 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.
Source_Used_Citation_Abbreviation:
13BIM03_SBB_03_ITRF00_xxx.txt
13BIM04_SBB_03_ITRF00_xxx.txt
13BIM08_SBB_03_ITRF00_xxx.txt
Process_Date: 2013
Source_Produced_Citation_Abbreviation: Chan13_SBB_xyz_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:
Datum Transformation: The text files were converted two separate times using VDatum version 3.2 producing two separate files with different vertical datums. The first transformation was from the data acquisition and processing datum (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 2009 (GEOID09). The second transformation was from ITRF00 to NAD83 for the horizontal reference frame and Mean Lower Low Water (MLLW) tidal datum using GEOID09.
Source_Used_Citation_Abbreviation: Chan13_SBB_xyz_ITRF00.txt
Process_Date: 2013
Source_Produced_Citation_Abbreviation: Chan13_SBB_xyz_NAD83_NAVD88_GEOID09_MLLW.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:
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
