Brian D. Andrews 20260521 1.0 raster digital data data release DOI:10.5066/P14NWTX8 Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts U.S. Geological Survey, Coastal and Marine Hazards and Resources Program https://doi.org/10.5066/P14NWTX8 https://www.sciencebase.gov/catalog/item/68b08577d4be021f0facf2d2 Brian D. Andrews Wayne E. Baldwin Seth D. Ackerman Charles R. Worley Eric M. Moore Alex R. Nichols Patrick J. Berube Emily C. Huntley Laura L. Brothers 2026 1.0 data release DOI:10.5066/P14NWTX8 Reston, VA U.S. Geological Survey Suggested citation: Andrews, B.D., Baldwin, W.E., Ackerman, S.D., Worley, C.R., Moore, E.M., Nichols, A.R., Berube, P.J., Huntley, E.C., and Brothers, L.L., 2026, High-resolution geophysical and sampling data collected in Nantucket Sound Massachusetts in the vicinity of Horseshoe Shoal, during USGS Field Activity 2023-001-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P14NWTX8 https://doi.org/10.5066/P14NWTX8 https://www.sciencebase.gov/catalog/item/68adc403d4be027f635b3f90 In May and June 2023, the U.S. Geological Survey, in collaboration with the Massachusetts Office of Coastal Zone Management, collected high-resolution geophysical and seafloor sampling data, in Nantucket Sound to understand the regional geology in the vicinity of Horseshoe Shoal. Geophysical data collected include swath bathymetry, backscatter, and seismic reflection profile data. Ground-truth data, including sediment samples, underwater video, and bottom photographs were also collected. This effort is part of a long-term collaboration between the USGS and the Commonwealth of Massachusetts to map the State’s waters. In addition to resolving coastal hazards, habitats and resources, these data can be used to better understand the Quaternary history of coastal Massachusetts including the influence of sea-level change and sediment supply on coastal evolution. This collaboration produces high-resolution geologic data that serve the needs of research, management, and the public. Data collected as part of this mapping cooperative continue to be released in a series of USGS Reports and Data Releases https://www.usgs.gov/centers/whcmsc/science/geologic-mapping-massachusetts-seafloor The purpose of this raster depth grid is to provide a high-resolution digital elevation model (DEM) of the seafloor in the vicinity of Horseshoe Shoal, Nantucket Sound. The final processed line files in Generic Sensor Format (GSF) are also published here to both serve as a USGS archive, and also to provide public access to the source files used to create the final depth and backscatter mosaics. Support for 2023-001-FA was provided to the USGS from the Massachusetts Office of Coastal Zone Management. Approximately 441 linear kilometers of multibeam echosounder data, 400 km of seismic reflection profiling data were collected during 8 survey days along tracklines spaced 87 or 52 meters apart. Part 2 of this survey included ground validation using SEABOSS imagery and sediment samples collected at 59 stations covering both the 2022-001-FA and 2023-001-FA survey areas. Data were collected using the R/V Rafael, owned and operated by the USGS Woods Hole Coastal and Marine Science Center. Additional information on both the 2022 and 2023 field activities are available from https://cmgds.marine.usgs.gov/services/activity.php?fan=2022-001-FA, https://cmgds.marine.usgs.gov/services/activity.php?fan=2023-001-FA 20230601 20230611 Bathymetry data were collected on the following dates: 20230601-20230602 (Julian day 152-153), 20230606-20230611 (Julian day 157-162) Complete None planned -70.48275673 -70.33291407 41.57851668 41.54220321 None U.S. Geological Survey USGS Woods Hole Coastal and Marine Science Center WHCMSC Coastal and Marine Hazards and Resources Program CMHRP Department of the Interior DOI Massachusetts Office of Coastal Zone Management CZM MassCZM field activity number 2023-001-FA R/V Rafael GeoTIFF Generic Sensor Format GSF multibeam echosounder multibeam bathymetry Reson Teledyne T20-P ISO 19115 Topic Category geoscientificInformation imageryBaseMapsEarthCover elevation USGS Thesaurus multibeam sonar sea-floor acoustic reflectivity bathymetry marine geophysics marine geology geospatial datasets USGS Metadata Identifier USGS:68b08577d4be021f0facf2d2 None United States of America Massachusetts Atlantic Ocean Nantucket Sound Horseshoe Shoal Eldridge Shoal Succonnesset Shoal Wreck Shoal None sea floor seafloor none 2023 No access constraints. Please see 'Distribution Information' for details. These data are marked with a Creative Commons CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Not to be used for navigation. U.S. Geological Survey Brian Andrews Geographer mailing and physical

384 Woods Hole Road

Woods Hole Massachusetts 02543-1598 USA 508-548-8700 x2348 508-457-2310 bandrews@usgs.gov https://www.sciencebase.gov/catalog/file/get/68b08577d4be021f0facf2d2?name=2023-001_FA_TeledyneSeaBat_T20P_Bathymetry_2m_browse.jpg Thumbnail image of 2-m multibeam echosounder bathymetry data collected within Nantucket Sound Massachusetts in the vicinity of Horseshoe Shoal, during USGS Field Activity 2023-001-FA. JPEG Brian D. Andrews Wayne E. Baldwin Charles R. Worley Eric M. Moore Alex R. Nichols William W. Danforth David S. Foster Seth D. Ackerman Laura L. Brothers 2023 1.0 data release DOI:10.5066/P9O5G5OT Reston, VA U.S. Geological Survey This previous data release was also published as part of the USGS/CZM cooperative and may be of interest to others because it is directly south of, and overlaps, with the data collected during USGS Field Activity 2023-001-FA. https://doi.org/10.5066/P9O5G5OT https://www.sciencebase.gov/catalog/item/63e3e041d34e9fa19a9bb703 This grid represents processed data collected using a Teledyne Reson SeaBat Integrated Dual-Head (IDH) T20-P multibeam echosounder (MBES) gridded at 2-m resolution. Quality control and data processing were conducted to remove spurious points and reduce sound speed artifacts (refraction) using Qimera (v. 2.5) multibeam processing software. Data collected along sonar calibration lines and cross lines used for data quality checks are not included in this grid, however, the trackline navigation for all lines are included in the 2023-001-FA_TeledyneT20P_Tracklines.shp shapefile included in this publication. 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). Vertical accuracy of the raw data based on system specifications may be approximately 1 percent of water depth (ranging from 0.026 to 0.15 meters based on the water depth range of 2.6 to approximately 15.5 meters MLLW within the survey area). The Applanix Wavemaster POS MV Attitude and Positioning system, used to correct for vessel roll, pitch, heave, and yaw, has a theoretical vertical accuracy of a few mm. Post-Processed Kinematic (PPK) GPS height corrections (from Applanix POSPac smoothed best estimate of trajectory (SBET) files) were used to reference soundings to the World Geodetic System 1984 (WGS 84) ellipsoid and remove water level fluctuations during the survey. Forty-six sound speed profiles acquired with AML-3LGR or Minos X CTDSV sound velocity profilers were used during processing to minimize acoustic refraction artifacts in the bathymetry data. Cross line and junction analysis was calculated using lines 20230610_172229,20230610_182756,20230610_185120,20230611_123336,20230611_143500. The mean difference between the crosslines and overlapping soundings was -0.022 meters, which meets IHO s-44 Order 1 standards. Additionally, uncertainty associated with the vertical transformation of the bathymetric grid from the WGS 84 ellipsoidal heights to the Mean Lower Low Water tidal datum is 0.1134124 meters as calculated by the VDatum tool (v. 4.7.1). U.S. Geological Survey Unpublished Material digital data disc 20230601 20230611 ground condition RAW Teledyne T20-P MULTIBEAM ECHOSOUNDER FILES 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 (both heads) s7k file. The s7k line files were created by the Teledyne UI using the following naming convention: YYYYMMDD_HHMMSS. 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. raw MBES data in Teledyne .s7k format 202306 2023-001-FA_TeledyneT20P_Bathymetry_2m_Draft U.S. Geological Survey Brian Andrews Geographer mailing and physical address

384 Woods Hole Rd.

Woods Hole MA 02543-1598 508-548-8700 x2348 508-457-2310 bandrews@usgs.gov 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. 3) A new 2-m resolution dynamic surface was created. Additional editing was conducted using the Swath and 3D editors to minimize inconsistencies and artifacts, and the dynamic surface was recomputed to reflect the changes. Finally, a new 2-m Static Surface was created using the Weighted Moving Average method and a Weighting Diameter of 1 cell. 202311 2023-001-FA_TeledyneT20P_2m_WGS84 PROCESSSING STEP 3: EXPORT AND TRANSFORM TO MLLW TIDAL DATUM. The static surface was exported as 2-m per pixel ASCII file referenced to UTM Zone 19N, WGS 84 and WGS 84 ellipsoidal heights, but the desired vertical datum of the final bathymetric surface is the MLLW tidal datum. The National Oceanic and Atmospheric Administration's Vertical Datum Transformation tool (VDatum v. 4.7.1) was used for the transformation. The process required transformation of the horizontal and vertical reference frames from UTM Zone 19, WGS 84 (ITRF 2008) and WGS 84 ellipsoidal heights to UTM Zone 19, NAD83_2011, MLLW (meters) using the GEIOD18 geoid model. The resulting ASCII raster was opened in ArcGIS Pro (v. 3.0) and then exported as a 32-bit floating point GeoTIFF (2023-001-FA_TeledyneT20P_Bathymetry_2m.tif.) using the "Data Export" tool. 20240103 2023-001-FA_TeledyneSeaBat_T20P_Bathymetry_MLLW_2m.tif PROCESSSING STEP 4: EXPORT PROCESSED LINE FILES TO GENERIC SENSOR FORMAT (GSF) The final processed line files were exported from Qimera *qpd format to GSF (v.3.1.0) for three purposes: 1) Time series backscatter processing for use in FMGT, 2)Internal USGS Archiving, 2) Sharing the processed line files in a common format for use in the public domain. Using Qimera (v.2.7.4) select lines in each julian day, Export to Raw Sonar files- GSF. The GSF export options "Include User Additional Soundings", "Include raw backscatter imagery", and "Flag all filtered soundings as manual edits" were selected. The output file is in the format 2023001-YYYYMMDD_HHMMSS.gsf. Where 2023001 is the USGS Field Activity Number (2023-003-FA) and remaining digits are the year/month/day_ hour/minutes/seconds of the start of the line. The vertical reference system for GSF files is WGS 84 Ellipsoidal heights in meters. 202504 2023001_YYYYMMDD_HHMMSS Raster Pixel 1916 6219 1 Universal Transverse Mercator 19N 0.9996 -69 0 500000 0 row and column 2.0 2.0 meters GCS_North_American_1983_2011 GRS_1980 6378137.000000 298.257222101 Mean Lower Low Water (MLLW) 0.1 meters Explicit depth coordinate included with horizontal coordinates Data values represent depths referenced to the Mean Lower Low Water (MLLW) tidal datum. Depth range is -2.66 to -15.499 meters. U.S. Geological Survey U.S. Geological Survey - ScienceBase mailing and physical address

Denver Federal Center

Building 810

Mail Stop 302

Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov Multibeam bathymetric data collected in Nantucket Sound Massachusetts in the vicinity of Horseshoe Shoal during USGS Field Activity 2023-001-FA using a dual-head Teledyne T20-P multibeam echosounder: includes the GeoTIFF image 2023-001-FA_TeledyneT20P_Bathymetry_2m.tif, the individual multibeam echo sounder line files in GSF format and the browse graphic 2023-001-FA_TeledyneT20P_Bathymetry_2m_browse.jpg, the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file (2023-001-FA_TeledyneT20P_Bathymetry_2m_meta.xml). Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. GeoTIFF ArcGIS Pro (v. 3.0) 32-bit GeoTIFF file GeoTIFF file derived from MBES bathymetry data collected by the U.S. Geological Survey - Woods Hole Coastal and Marine Science Center and the associated metadata. Use any zip decompression utility 16.3 https://www.sciencebase.gov/catalog/item/68b08577d4be021f0facf2d2 https://www.sciencebase.gov/catalog/file/get/68b08577d4be021f0facf2d2 https://doi.org/10.5066/P14NWTX8 The first link is to the page containing the data, the second link downloads all data available from the page as a zip file, and the third link is to the publication landing page. Generic Sensor Format GSF (v. 3.1.0) Generic Sensor Format GSF files derived from MBES bathymetry data collected by the U.S. Geological Survey - Woods Hole Coastal and Marine Science Center and the associated metadata. 2023-001-FA_GSF.zip 36000 https://www.sciencebase.gov/catalog/item/68b08577d4be021f0facf2d2 https://www.sciencebase.gov/catalog/file/get/68b08577d4be021f0facf2d2 https://doi.org/10.5066/P14NWTX8 GSF files are in 8 separate folders in one zip file. The first link is to the page containing the data, the second link downloads all data available from the page as a zip file, and the third link is to the publication landing page. none To utilize these data, the user must have software capable of uncompressing the zip file and viewing GSF files. 20260521 U.S. Geological Survey Brian Andrews Geographer mailing and physical address

384 Woods Hole Rd.

Woods Hole MA 02543-1598 508-548-8700 x2348 508-457-2310 whsc_data_contact@usgs.gov The metadata contact email address is a generic address in the event the person is no longer with the USGS. FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time