Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports<http://woodshole.er.usgs.gov/project-pages/coastal_mass/html/current_map.html>. This spatial dataset is from the Cape Ann and Salisbury Beach Massachusetts project area. They were collected in two separate surveys in 2004 and 2005 and cover approximately 325 square kilometers of the inner continental shelf. High resolution bathymetry and backscatter intensity were collected in 2004 and 2005. Seismic profile data, sediment samples and bottom photography were also collected in 2005.
U.S. Geological Survey, 2008, BATH_IS5m - 5 meter ArcRaster grid of swath bathymetry of inshore area of Cape Ann - Salisbury Beach Massachusetts survey area.: Open-File Report 2007-1373, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.This is part of the following larger work.Online Links:
Barnhardt, Walter A. , Andrews, Brian D. , Ackerman, Seth D. , Baldwin, Wayne E. , and Hein, Christopher J. , 2008, High-Resolution Geological Mapping of the Inner Continental Shelf: Cape Ann to Salisbury Beach, Massachusetts.: Open-File Report 2007-1373, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.Online Links:
This is a Raster data set. It contains the following raster data types:
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 5.001966
Ordinates (y-coordinates) are specified to the nearest 5.001966
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.
| Range of values | |
|---|---|
| Minimum: | -2.5 |
| Maximum: | -28.8 |
| Units: | meters |
508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
The purpose of these data is to establish high-resolution acoustic depth measurements of the seafloor for regional geologic framework investigations. These data cover 69 square kilometers of the near shore survey area between Cape Ann and Salisbury Beach, Massachusetts, in depths between 2m and 30m.
A patch test was conducted at the beginning of the survey in order to measure roll angle offsets. Roll angle offsets can have a strong effect on the accuracy of depth measurements. (The roll angle offset is the difference between the motion sensor vertical measurement and the nominal mount angle of the transducers (30 degrees)). The calculated roll angle offsets were stored within the SEA Swath Processor acquisition software.
Navigation: The USGS established a Real-Time Kinematic Global Positioning System (RTK-GPS) that provided horizontal (x and y) and vertical (z) positioning during the survey. The RTK-corrected GPS signal was sent to the ship once every second from a base station positioned on the roof of the Air Force Antenna Station (USAF/AFRC/SNHA) in Ipswich, Massachusetts. Shipboard navigation data (x, y, and z) were stored in Hypack, Inc. Hydrographic Survey Software (<http://www.hypack.com>) raw data files and used for positioning of geophysical instrumentation.
The offset between orthometric (NAVD88) and local chart datum (MLLW) as reported at the NOAA Tidal Station #8440452, Parker River National Wildlife Refuge, was applied to the RTK signal. This allows for elevations (z) received at the shipboard RTK antenna to be referenced to Mean Lower Low Water (MLLW) (that is, elevations are stored as distance of the RTK antenna above MLLW).
During post-processing, the distance of the RTK antenna above the water-line is removed from the stored RTK elevations. The resulting value is then applied to the bathymetric soundings, yielding data referenced to MLLW.
Person who carried out this activity:
508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
Person who carried out this activity:
508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
Person who carried out this activity:
508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
Person who carried out this activity:
508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
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, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.Online Links:
Ackerman, Seth D. , Butman, Bradford, Barnhardt, Walter A. , Danforth, William W. , and Crocker, James M. , 2006, High-Resolution Geologic Mapping of the Inner Continental Shelf: Boston Harbor and Approaches, Massachusetts: Open-File Report 2006-1008, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.Online Links:
These data were navigated using Real-Time Kinematic Global Positioning System (RTK-GPS) which provides horizontal positional accuracies (x and y) on the decimeter scale (<http://www.noaa.gov>; <http://www.nos.noaa.gov>; <http://www.ngs.noaa.gov>).
Vertical accuracy of the acquisition system may approximate 1% of water depth, 0.1-0.3 meters within the survey area. However, overall vertical accuracies of <= 0.5 m are assumed based on the following considerations. Ship motion was recorded with a TSS DMS 2-05 and used to correct for heave, pitch, roll and yaw. RTK-GPS was used to establish water-level heights relative to Mean Lower Low Water (MLLW), providing decimeter-scale accuracies. Refraction artifacts were minimized by acquiring a range of sound velocity profiles throughout the survey area to model the sound velocity structure of the water column. Fluctuations in the vessel draft due to fuel and water usage were not determined.
Soundings were processed and edited using CARIS HIPS (ver 6.1). Although the soundings were manually edited, small data spikes may exist at outer edges of some swaths. In addition, small gaps between adjacent survey lines may exist in depth less than 14 meters. Swath bathymetry was collected along additional offshore tie-lines for use with the seismic profiles and for cross-track depth comparison. Bathymetric data collected on these offshore tie lines are not included in this grid.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Intended scale of data is 1:25,000. Data are not intended for navigational use. 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.
508-548-8700 x2348 (voice)
bandrews@usgs.gov
Downloadable Data
Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. 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.
| Data format: | WinZip file containing the ArcRaster grid of swath bathymetric data collected in the near shore survey area of the Cape Ann to Salisbury Beach Survey Area. in format WinZip (version 9.0) ESRI Raster GRID format Size: 6.2 Mb |
|---|---|
| Network links: |
<https://pubs.usgs.gov/of/2007/1373/GIS/raster/bathymetry/bath_is5m.zip> |
| Media you can order: |
DVD-ROM
(Density 4.75
Gbytes)
(format UDF)
Note: None
|
These data are available as a ArcInfo 32-bit floating point binary grid in Environmental Systems Research Institute (ESRI) format. The grid consists of two folders, one with the "grid name", and one "info" folder. The two folders for each grid are compressed into one file using WinZip (ver. 9.0) software. To utilize these data, the user must have software capable of uncompressing the WinZip file and importing and viewing an ESRI ArcRaster grid. The two folders for each grid must be uncompressed to the same folder. If during the process of extracting multiple grids in WinZip format to the same folder, the user is prompted by WinZip software to "overwrite existing files" in the info folder select the "yes" option.
508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
