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/68b085a3d4be021f0facf2d5 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 backscatter mosaic is to measure the relative acoustic reflectance (backscatter) values of the seafloor. This mosaic provides information on the reflectivity of the seafloor surficial sediments in the vicinity of Horseshoe Shoal. 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 area. 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/fan_info.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 -70.48279341 -70.31008553 41.57910429 41.54220451 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 backscatter backscatter time-series Reson Teledyne T20-P ISO 19115 Topic Category geoscientificInformation imageryBaseMapsEarthCover USGS Thesaurus multibeam sonar sea-floor acoustic reflectivity marine geophysics marine geology geospatial datasets USGS Metadata Identifier USGS:68b085a3d4be021f0facf2d5 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. 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/68b085a3d4be021f0facf2d5?name=2023-001-FA_TeledyneSeaBat_T20P_Backscatter_1m_browse.jpg Thumbnail image of 1-m multibeam echosounder backscatter 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 raster mosaic represents processed dual-head Teledyne SeaBat T20-P multibeam echosounder (MBES) backscatter data gridded at 1-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 mosaic, 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 satellite 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). PROCESSING STEP 1: IMPORT GSF FILES INTO QPS FMGT SOFTWARE. 1) Create a new QPS FMGT (ver. 7.10.1) Project using the UTM 19, WGS 84 coordinate system. Processing parameters were set to use the "Reson SeaBat T20P Focused MBES". 2) Import each of the integrated GSF files containing data from both heads into the project by Julian day folder. All settings were checked for the "adjust" processing section in FMGT. 3) Filter settings used a flat Angle Varying Gain (AVG) algorithm and 300 AVG window size. The contact person for this and all subsequent processing steps below is Brian Andrews. The GSF files used as the source for the time series backscatter mosaic are published in this data release. The process steps used to create the GSF Files are explained in Processing Step 4 of the 2023-001-FA_TeledyneSeaBat_T20P_Bathymetry_MLLW_2m.tif metadata. 202412 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 PROCESSSING STEP 2: CREATE TIME SERIES BACKSCATTER MOSAIC AND EXPORT AS GEOTIFF. 1) Create a 1-meter resolution mosaic using the "Beam Time Series" and "Blend" options. 2) The mosaic was exported as an 8-bit grayscale geotiff at 1-m resolution. 202505 2023-001-FA_TeledyneT20P_Backscatter_1m.tif Raster Pixel 4099 14339 1 Universal Transverse Mercator 19N 0.9996 -69 0 500000 0 row and column 1.0 1.0 meters GCS_North_American_1983_2011 GRS_1980 6378137.000000 298.257222101 No data value is 0. 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 backscatter 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_Backscatter_1m.tif, the browse graphic 2023-001-FA_TeledyneT20P_Backscatter_1m_browse.jpg, and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file (2023-001-FA_TeledyneT20P_Backscatter_1m_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 FMGT (v. 7.11,1) 8-bit GeoTIFF file GeoTIFF file derived from MBES backscatter data collected by the U.S. Geological Survey - Woods Hole Coastal and Marine Science Center and the associated metadata. Use any zip decompression utility 42 https://www.sciencebase.gov/catalog/item/68b085a3d4be021f0facf2d5 https://www.sciencebase.gov/catalog/file/get/68b085a3d4be021f0facf2d5 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. none To utilize these data, the user must have software capable of viewing GeoTIFF 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