Linear gaps between consecutive polyline features in this shapefile reflect those time periods where data were not recorded
This shapefile contains tracklines for all Teledyne Reson SeaBat T20-P files collected during survey 2023-001-FA. Data collected along sonar calibration lines and cross lines were used for data quality control but are not included in the final bathymetry and backscatter mosaics.
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Navigation data were acquired using the WGS 84 coordinate system with an Applanix POS MV Wavemaster (model 220, V5), which utilizes multiple GNSS satellites and acceleration data from a Motion Reference Unit (MRU) and GNSS azimuthal heading. The POS MV was configured with two AeroAntenna Technologies GNSS antennas located at either end of a 2-m baseline, which was oriented athwartship and mounted atop the after end of the cabin. DGPS positions were obtained from the primary antenna located on the starboard end of the baseline, and the positional offsets between the antenna and the navigational reference point (the POS MV IMU) were accounted for in the Applanix POSView (version 11.00) acquisition software. DGPS positions are horizontally accurate to 0.5 - 2 meters, but accuracy can increase to less than 10 cm after post-processing with Applanix POSPac (version 8.8).
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: Unpublished Material
Title: raw MBES data in Teledyne .s7k format
Geospatial_Data_Presentation_Form: digital data
Type_of_Source_Media: disc
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20230601
Ending_Date: 20230611
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: RAW Teledyne T20-P MULTIBEAM ECHOSOUNDER FILES
Source_Contribution:
Multibeam echosounder (MBES) bathymetry and backscatter data were collected using integrated, dual-head Teledyne Reson SeaBat T20-P sonars. The pair of mills cross transmit and receive arrays were mounted side-by-side within a bracket that oriented them at opposing 30-degree angles (relative to horizontal). The bracket was pole-mounted on the starboard side of the R/V Rafael so that the sonar arrays were oriented athwart ships (primary and secondary arrays facing outward and down to port and starboard, respectively) and located approximately 1.215 m below the waterline when deployed. Vessel navigation and attitude data were acquired using an Applanix POS MV Wavemaster (model 220, V5) configured with two AeroAntenna Technologies GNSS antennas located at either end of a 2-m baseline, which was oriented athwartship and mounted atop the after end of the cabin, and the wetpod MRU mounted atop the sonar bracket just aft of the pole. An AML Micro X SV mounted on the sonar bracket monitored sound speed near the sonars during acquisition, and AML-3LGR or Minos X CTDSV profilers were used to collect water column sound speed profiles 3 to 7 times each survey day. The Teledyne SeaBat User Interface (version 5.2.0.1) was used to control the sonars, which were operated in intermediate mode at full power (220 dB), with frequency-modulated pulse at 400 kHz. The range of the 1024 across track beams formed by the sonars were adjusted manually depending on water depth and resulted in combined swath widths of 50 to 300 meters or typically 3 to 6 times the water depth. Data were monitored and recorded using the Teledyne SeaBat User Interface (UI) (version 5.2.0.1) and Hypack/Hysweep (v. 2022). The SeaBat User Interface logged the navigation, attitude, bathymetry, time-series backscatter, (using the normalized backscatter datagram), and water column data to s7k format files for each sonar into one, integrated s7k file. The s7k line files were created by the Teledyne UI using the following naming convention: YYYYMMDD_HHMMSS.
Process_Step:
Process_Description:
PROCESSING STEP 1: QIMERA DATA PROCESSING.
Multibeam bathymetry processing within Qimera multibeam processing software (version 2.5.0) during the survey consisted of the following workflow:
1) A new Qimera project was created with projection information set to Universal Transverse Mercator (UTM) Zone 19N, WGS 84. The s7k files for each Julian day were imported to the project using the Source/add raw sonar files menu.
2) A Vessel configuration file was created with the linear and angular installation offsets for each T20-P sonar head as well as vendor specified uncertainty values for each of the survey sensors.
3) Sound Velocity profiles for each day were imported and converted to Qimera using the Source/import/Caris svp menu. Each profile was reviewed for incorrect records using the SVP editor. Incorrect records near the surface or within the water column were flagged using the "reject selection" context menu.
4) Predicted Tides from the Woods Hole, MA tidal station (id 8447930) for the month of June, were downloaded and imported using the Source/Add Tide Files menu. Predicted tides were referenced to Mean Lower Low Water (MLLW) at 6-minute intervals.
5) Delayed heave data from the raw POS MV files (.000) were used to update raw sonar lines using the Source/add binary navigation menu function.
6) The Processing Settings Editor was used to establish the following:
a) Sound velocity Strategy: nearest in time, Use surface sound speed as first entry in raytrace profile.
b) Position, Motion, and Heading Source Priorities: were set position 1, Motion 1, and Motion 1 respectively.
c)Vertical Referencing was set to the Woods Hole predicted Tide file.
d) Blocking filters were set to Across Track = 0-to-80 meters on each sonar head. Colinearity Fail was also selected.
7)Each raw sonar file was processed using the settings described above.
8) A preliminary, 2-m resolution dynamic surface (2023-001-FA_2m_Draft) was created and reviewed for inconsistencies and anomalies. The swath editor was used to remove spurious points through manual editing and filter application.
The contact person for this and all subsequent processing steps below is Brian Andrews.
Process_Date: 202306
Source_Produced_Citation_Abbreviation: 2023-001-FA_TeledyneT20P_Bathymetry_2m_Draft
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Brian Andrews
Contact_Position: Geographer
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Rd.
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2348
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: bandrews@usgs.gov
Process_Step:
Process_Description:
PROCESSING STEP 2: APPLY POST PROCESSED SBET FILES AND EDIT SOUNDINGS.
Post-survey processing within Qimera (version 2.5.0) consisted of the following workflow:
1) Post-processed navigation, vessel attitude, and GNSS height data from POSPac Smoothed Best Estimate of Trajectory (SBET) files, and post-processed RMS attitude error data from POSPac smrmsg files were used to update each Sonar file using the Source/Add Binary Navigation Files function. The SBET files were referenced to the WGS 84 Ellipsoid (meters).
2) Once the sbet and smrmsg files were imported for each raw sonar file, the Processing Settings Editor was used to replace the attitude and tide referencing data using the following settings:
a) Position, Motion, and Heading Source Priorities were superseded by "sbet" file.
b) Vertical Referencing Method was set to "RTK (Accurate Height)" using the "sbet" file.
Process_Date: 202311
Process_Step:
Process_Description:
PROCESSSING STEP 3: EXPORT TRACKLINE NAVIGTATION AND CONVERT TO SHAPEFILE.
Processed navigation for each sonar file was exported from Qimera using the Export/Raw Sonar File/Export Trackline to ASCII menu. A python Jupyter notebook utilized the python modules pandas (version 1.5.2), geopandas (version 0.12.1), pyproj (version 3.4.0), shapely (version 1.8.5.post1), and sqlite3 (version 3.40.0) to process the navigation data for each profile line in the following steps. The separate ascii files were imported to pandas dataframes and sub-sampled to preserve the first and last records and records at ten second intervals in between. Coordinates for the reduced data were transformed from UTM Zone 19N (meters) to WGS84 geographic (decimal degrees), UTC date time objects reformatted to produce columns containing the filename, a combined year-julian day number string, a combined Julian day number UTC time string, survey id, vehicle id, and device id. Geopandas and shapely were used to create a point geometry column from the geographic coordinates. SQL queries was used to load each navigation dataframe into a geospatial SQLite database using the pyspatialite interface. Records were appended to two database tables, the first containing the reduced coordinate navigation, and the second containing trackline features created from the coordinated navigation point geometries. The trackline table was imported into QGIS (v.3.26) from the SQLite database, then exported (Right click on database feature class > Data > Save Features As) to the new Esri point and polyline shapefile ‘2023-001-FA_TeledyneT20P_Tracklines'. Additional processing included adding and calculating the fields described in the Entity and Attribute Section below.
Process_Date: 20231203
Source_Produced_Citation_Abbreviation: 2023-001-FA_TeledyneT20P_Tracklines.shp
