Nahant to Gloucester, 1m resolution Sidescan Sonar Mosaic (SS_MOS1M.TIF)
These data are high-resolution acoustic backscatter measurements of the seafloor offshore of Massachusetts, from Nahant to Gloucester. Approximately 127 km2 of the inner shelf were mapped in the nearshore region between the 10m and 40-m isobath.
Andrews, Brian D., 2005, Nahant to Gloucester, 1m resolution Sidescan Sonar Mosaic (SS_MOS1M.TIF): Open File Report 2005-1293, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.
Barnhardt, Walter A., Andrews, Brian D., and Butman, Bradford, 2006, High-Resolution Mapping of the Inner Continental Shelf: Nahant to Gloucester, Massachusetts: Open-File Report 2005-1293, U.S. Geological Survey, Reston, VA.
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 1.000000
Ordinates (y-coordinates) are specified to the nearest 1.000000
Planar coordinates are specified in meters
The horizontal datum used is D_WGS_1984.
The ellipsoid used is WGS_1984.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257224.
These data were collected under a cooperative agreement with the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center. High resolution bathymetry, backscatter intensity, and seismic profile data were collected over 127 km2 area covering a portion of the South Essex Ocean Sanctuary to characterize the surface and subsurface of the seafloor for regional geologic framework investigations.
Backscatter data were collected during two different surveys. Survey RAFA03007
began Monday, 22 Sep 2003 (JD267) and ended on Tuesday, 14 Oct 2003 (JD287). RAFA04002 began 17 Apr 2004 (JD 108) and ended on 2 May 2004 (JD123).
Sidescan data were acquired with Edgetech DF-1000, dual frequency towed sidescan sonar with average layback of
Collected with 150m range layback = 6 meters
Date: unknown (process 2 of 7)
raw .xtf data were processed and corrected for slant range corrections in XSONAR/SHOWIMAGE
Date: unknown (process 3 of 7)
the Xsonar files were mosaiced in Xsonar and then exported to PCI Geomatica as raw files
Date: unknown (process 4 of 7)
PCI Geomatica mosaiced individual line files and georeferenced to UTM Z 19
Date: unknown (process 5 of 7)
The positional accuracy of the final 1m resolution mosaic was increased by further georeferrencing (rubber sheeting) to the submetrix interferometric sonar backscatter mosaic. The interferometric data has higher order positional accuracy than the towed sidescan-sonar because the GPS antenna is mounted on top of the same pole as the interferometric sonar and there is no inacuracies from towfish layback. The rubber sheeting was calculated in ArcGIS with the Georefferencing.
Date: 18-Nov-2015 (process 6 of 7)
Edits to the metadata were made to fix any errors that MP v 2.9.30 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Online linkages were fixed (some needed to point to pubs.usgs.gov). None of the original process steps had process dates, so those were set to "unknown". Time period of content date format was fixed. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.
Person who carried out this activity:
U.S. Geological Survey
Attn: VeeAnn A. Cross
384 Woods Hole Rd.
Woods Hole, MA
508-548-8700 x2251 (voice)
Date: 20-Jul-2018 (process 7 of 7)
USGS Thesaurus keywords added to the keyword section.
Person who carried out this activity:
How accurate are the heights or depths?
The RTK corrected signal was sent from a USGS survey-specific base station at the lighthouse on Eastern Point Lighthouse. The base station occupied a DMA monument, however, the x, & y positions were calculated for that location using a 3 day average of 12 hour data sets using the Online Positioning User Service (OPUS, National Geodetic Survey) solution. Sidescan tow fish layback was 6 meters.
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
Although this data set has been used by the U.S. Geological Survey (USGS), no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
This image is available as a GeoTIFF image with an accompanying world file. To utilize this data, the user must have an image viewer, image processing or GIS software package capable of importing a GeoTIFF image.