Woods Hole Science Center
A GIS Library of Multibeam Data for Massachusetts Bay and the Stellwagen Bank National Marine Sanctuary, Offshore of Boston, Massachusetts, USGS DS 99; Version 1.0
Images and grids of bathymetry, shaded relief bathymetry, and backscatter intensity data from the multibeam surveys may be viewed in an ArcMap project. The ArcMap project file is stored in the massbay_gis directory. In order to view and manipulate the gridded data sets in this project the Spatial Analyst extension must be loaded. ESRI (www.esri.com) supports Windows 95/98/NT/2000/XP and UNIX systems. The ArcMap project is only available from the DVD version of this publication.
All views within the project files are projected in a Mercator coordinate system (Spheroid GRS80, Central meridian -70.31666666667, Latitude of true scale 41.65, False easting 0, False northing 0, Map units in meters). All raster image and grid data are also in Mercator projection. All point and vector data are stored in decimal degrees.
The multibeam data east of 70° 36' W have been corrected from earlier editions for an omission in the initial processing that did not project the data on a sphere. All data has also been shifted from previous editions 1/2 grid cell to the northwest to correct a gridding error. The multibeam bathymetric data were corrected for tidal elevation during the survey using sea level measured at the NOAA Boston tide gage. Further processing to correct for the spatial and temporal changes in tidal elevation across the survey area may be undertaken at a future date.
There are two data frames in the (ArcMap) project:
Massachusetts Bay shows the data used to make the 1:125,000 scale map of Massachusetts Bay. These data also cover the area of the 1:25,000 scale maps of Quadrangles 1-18 and the 1:60,000 scale maps of the Stellwagen Bank National Marine Sanctuary.
The Massachusetts Bay map also uses onshore topography from the U.S. Geological Survey Digital Elevation Model (DEM) at a resolution of 30 m/pixel.
Western Massachusetts Bay Map Quadrangle 1-3 shows the multibeam data (at 6 m resolution) used to make the three 1:25,000 scale western Massachusetts Bay Quadrangle maps.
Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S. Government.