Multibeam bathymetric data collected in the vicinity of Woods Hole, Massachusetts, during USGS Field Activity 2021-037-FA using a dual-head Teledyne Seabat T20-R multibeam echo sounder (32-bit GeoTIFF, UTM Zone 19N, WGS 84, GEOID 18 (MSL) Vertical Datum, 50cm resolution)

PROCESSING STEP 1: QPS Qimera DATA PROCESSING.
Multibeam bathymetry processing within QPS Qimera software (version 2.5.4) of data collected during the survey consisted of the following flow:
1) A new Qimera project was created on disk using UTM zone 19N, WGS84 as the horizontal reference frame.
2) Raw T20R s7k files were imported into Qimera project using the Source/Add Raw Sonar Files menu and converted to the Qimera QPD format. This step creates a new vessel file which was named Rafael_IDH.
3) The Rafael vessel file was edited using the Qimera Vessel Editor and updated to reflect the offsets between the NRP and both the starboard and port transmit/receive transducer arrays. The draft of the NRP below the water line was also entered into the configuration.
4) Delayed heave data from raw POS MV files (.000) were imported using the Source/Add Binary Navigation Files menu. Using data from these files, a new motion system reference was created (POS_TrueHeave) selecting the true heave checkbox. This reference system was automatically added to the existing vessel file.
5) The collected sound velocity profile data was imported into the Qimera project using the Source/Input SVP dialog and selecting the CARIS formatted sound velocity data file.
6) Using the Tools/Edit Processing Settings dialog, the vertical referencing tab was selected and the delayed heave source priorities were set to use the true heave from the raw POS MV files.
7) Using the Tools/Edit Processing Settings dialog, the sound velocity tab was selected and the sound velocity strategy was updated using the "specific sound velocity profile" checkbox referencing the imported sound velocity data values. The surface sound speed priority was set to the surface sound speed collected by the AML sensor mounted on the sonar bracket, and this value was selected as the first entry in the raytrace profile.
8) A preliminary, 50 centimeter resolution dynamic surface was created and reviewed for inconsistencies and anomalies. The Qimera swath editor and 3D editor was used to remove spurious points through manual editing and filter application.

PROCESSING STEP 2:APPLY POST PROCESSED SBETs ANND FINAL EDITS.
1) Post-processed navigation, vessel attitude, and GPS height data from the POSPac Smoothed Best Estimate of Trajectory (SBET) file (sbet_Mission 1.out), and post-processed RMS vessel attitude error data from the POSPac smrmsg file were imported using the Source/Add Binary Navigation Files menu. Using data from these files, a new motion system reference (POS_MOTION) was created selecting the motion checkbox, and a new position system reference was created (POS_POSITION) selecting the position and height checkboxes. These two reference systems were automatically added to the existing vessel file.
2) Using the Tools/Edit Processing Settings dialog, the vertical referencing tab was selected and the vertical referencing method was changed from "None" to "RTK (Accurate Height)" and the POS_POSITION checkbox was selected as the priority. The position, motion, heading tab was then selected and the SBET processed position/motion values were applied by selecting the following:
The position source priorities were changed to the POS_POSITION reference. The motion source priorities were changed to the POS_MOTION reference. The heading source priorities were changed to the POS_MOTION reference.
The dynamic grid surface was then automatically updated to reflect the new position/motion processed values, and the soundings were now vertically referenced to the WGS 84 ellipsoid.
3) The equipotential surface model, GEOID18, was downloaded from the National Geodetic Survey (NGS) website. This gravimetric geoid model approximates mean sea level (MSL) and is consistent with the North American Vertical Datum of 1988 (NAVD 88). This binary grid was directly imported into ArcGIS Pro v3.1 and exported to a 32-bit floating point geotiff.
4) The 32-bit GEOID18 geotiff was imported into Qimera and converted to an internal Qimera grid format.
5) Using the Tools/Edit Processing Settings dialog, the vertical referencing tab was selected and a separation model (GEOID 18 model from the NGS) from step 9 was added to the vertical geodetic offset portion of the dialog. The line files were reprocessed using this model in conjunction with ellipsoidal heights, referencing each sounding to the GEOID 18 gravimetric model which is consistent with MSL for the Woods Hole area.
6) Exported a final depth grid out of Qimera as a 32bit floating point Raster (2021-037-FA_ResonT20R_Bathymetry_50cm.tif).
7) Exported the final edited line files into the GSF format for backscatter mapping in FMGT (see backscatter process steps).

The metadata was edited to fix an author middle initial in the larger work citation (20250116).