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, CABATH5M - 5 meter ArcRaster Bathymetric grid of both the inshore and offshore area of Cape Ann - Salisbury Beach 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 5.000000
Ordinates (y-coordinates) are specified to the nearest 5.000000
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.
| Range of values | |
|---|---|
| Minimum: | -2.9 |
| Maximum: | -91.37 |
| Units: | meters |
508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
The purpose of this grid is to provide a merged bathymetric dataset of the nearshore and offshore survey areas that covers 100 percent of the seafloor inside the Cape Ann to Salisbury Beach survey areas.
1) Calculated new grid by selecting all areas in bath_is5m with a depth less than 14m deep using ESRI ArcInfo Workstation (ver 9.2 ) Grid Module Syntax= EXT14M = select((bath5mfinal), 'value > -14')
2) Converted the temporary grid of depth less than 14 meters to a point feature class using the "Raster to Point" tool (ArcGIS ArcToolbox ver. 9.2).
3) Create empty TIN using "Create TIN" tool, then add x,y,z point feature class using the "Edit TIN" tool (ArcGIS ArcToolbox ver. 9.2). Creating a TIN from the points filled in the gaps between lines.
4) Created a polygon feature class to use as a hard clip boundary and then added to the TIN with the "Edit TIN" Tool (ArcGIS ArcToolbox ver. 9.2).
5) Converted the TIN back to a 10 meter resolution grid (nn10mfil) using "Tin to Raster" Tool (ArcGIS ArcToolbox ver 9.2) using the natural neighbors and 10 m cell size option. A 10m cell size was used to further smooth the data.
6) Mosaicked the 5m inshore grid (bath_is5m with gaps) with the 10m inshore grid (<14m with no gaps) into a new 5m grid (bath_is5mInt) covering the near shore survey area. Used the "Mosaic To New Raster" tool (ArcGIS ArcToolbox ver. 9.2) with the following parameters: Input Rasters: nn10mfil, bath_is5m Output Raster: is5m_merge Cellsize: 5
Mosaic Method: First- This option means the output cell value of the overlapping areas will be the value from the first raster in the list (bath_is5m). Where the two grids do not overlap (the gaps) the nn10mfil values we used.
Person who carried out this activity:
508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@usgs.gov
Data sources produced in this process:
Count: 131,668 Min: -4.23 meters Max 2.77 meters Mean: -0.24 meters Standard Deviation: 0.177 meters
The offshore data (SAIC RESON 8101) is 0.24 meters shallower than the USGS inshore data. A correction factor of 0.24 meters was added to the inshore data so that the mosaicked bathymetric grid would not have a big depth difference along the area of overlap.
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
Data sources produced in this process:
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:
The horizontal accuracy of this merged grid varies, based on the accuracy of the input grids. The data in "bath_is5m" was collected using a Real-Time Kinematic GPS signal from a USGS base station established for the survey. The data in "bath_os5m" was collected using the Differential Global Positioning System signal from the U.S. Coast Guard.
The mean depth differences between nearshore (USGS) survey and the offshore (SAIC) data is 0.24 meters. The data from the two surveys overlap 150-200 meters along there common boundary. In the area of overlap, the offshore data is 0.24 meters (mean) shallower. These differences can be can be attributed to the use of differing tidal models for the two surveys. SAIC utilized a zoned tidal model provided by NOAA, whereas the USGS used kinematic water level heights recorded in real time aboard the R/V Connecticut A zoned tidal model is based on a compilation of historical water level heights, which take into account extreme highs and lows, and is generally very accurate. However, water level heights at the time of data collection are influenced by local wind and wave setup conditions that are not taken into account by the zoned tidal model. The kinematic water level heights recorded by the USGS aboard the R/V Connecticut reflect these local variations due to wind and wave setup and thus could account for the observed differences in the bathymetric surfaces generated by SAIC and the USGS.
Survey lines run for cross line junction analysis are not included in this grid.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Data are not intended for navigational use. The intended scale of these data is 1:25,000. 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 Cape Ann to Salisbury Beach Survey Area. in format ESRI Grid (version ArcGIS 9.2) ESRI Raster GRID format Size: 92.370 |
|---|---|
| Network links: |
<https://pubs.usgs.gov/of/2007/1373/GIS/raster/bathymetry/cabath5m.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
