U.S. Geological Survey, 2003, Sea Floor Topography and Backscatter Intensity of the Historic Area Remediation Site: U.S. Geological Survey, Woods Hole, MA.This is part of the following larger work.Online Links:
Butman, Bradford, Gutierrez, Benjamin T., ten Brink, Marilyn Buchholtz, Schwab, William C., Blackwood, Dann S., Mecray, Ellen L., and Middleton, Tammie J., 2003, Photographs of the Sea Floor Offshore of New York and New Jersey: U.S. Geological Survey Open-File Report of01-470, U.S. Geological Survey, Woods Hole, MA.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 3
Ordinates (y-coordinates) are specified to the nearest 3
Planar coordinates are specified in meters
The ellipsoid used is World Geodetic System 84.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257.
The multibeam observations in the HARS were originally published in Butman and others (2002), U.S. Geological Survey Open-File Report 00-503 (see cross-reference citation). These data have been reprocessed to correct for an error in the software that projected the data on a sphere rather than on the WGS84 ellipsoid, and to stretch the backscatter intensity and shaded relief images the same as the Hudson Shelf Valley images.
U. S. Geological Survey
c/o Bradford Butman
Oceanographer
384 Woods Hole Rd
Woods Hole, MA 02543-1598
USA
508.548.8700x2212 (voice)
508-457-2309 (FAX)
bbutman@usgs.gov
- Hours_of_Service: 8 a.m. - 5 p.m.
These data are included in this publication to provide bathymetry and backscatter intensity of the sea floor for maps showing the locations of images and samples obtained in the New York Bight.
(A.) Demultiplex, or unravel, the acquired Simrad data files using RT to generate separate files containing navigation, depth soundings, sidescan sonar backscatter values, and sound velocity information.
(B.) Automatically reject bad data (autoRejectSoundings). For the multibeam soundings, reject data outside expected depth ranges (operator's decision based on nautical chart data); for navigation data, reject fixes with poor GPS statistics.
(C.) Edit the navigation data on-screen using jview to remove undesirable points, including turns at the ends of survey lines.
(D.) Edit the multibeam soundings on-screen using swathed to remove individual anomalous soundings.
(E). Merge tidal information and the corrected navigation back (mergetide and mergenav) into the data files. Tidal information was obtained from the NOAA tide server using tide station 8531680 located at Sandy Hook, //www.co-ops.nos.noaa.gov/) Final tidal corrections were made in the lab using a different procedure (see below).
(F.) Map the bathymetric soundings from each processed data file onto a Mercator grid using weigh_grid with node spacings and scale selected by the operator.
(G.) Map the extracted sidescan sonar backscatter values onto a digital mosaic using mos2 in the Mercator projection at a scale selected by the user.
(H.) Using addSUN, generate bathymetric raster files using the mapped grid node information to depict the depth information in a shaded relief Mercator map. A Mercator projection allows individual map areas to be joined edge to edge when creating a composite image. The shaded relief images were generated using a sun elevation angle of 45 degrees from an azimuth of 0 degrees, and a vertical exaggeration of four times to emphasize sea floor features.
(I.) Generate a false colored image using mix_ci by combining the bathymetric and backscatter raster mosaics into a single image, also in the Mercator projection.
(2) Data processing and analysis in the lab included:
(A.) Removing sound refraction artifacts from the data (using the refraction tool in swathed) due to insufficient sound velocity profile information and varying water masses within the study area.
(B.) The measured elevations were adjusted for fluctuations in sea level during the survey by subtracting tidal elevations predicted by a tidal model and low-frequency sea level observed at the National Oceanic and Atmospheric Administration Sandy Hook tide station located at 40 degrees 28 minutes N., 74 degrees 0.6 minutes W. The tidal model utilized 9 constituents derived from a 4-month bottom pressure record obtained at Station A, located at 40 degrees 23.4 minutes N., 73 degrees 47.1 minutes W. in 38 m water depth about 2.7 km east of the HARS, during the winter of 1999-2000. An estimate of the error due to sea level remaining in the multibeam observations after the sea level correction is about 3 cm.
(C.) Two corrections have been made to the HARS multibeam data as published in Butman and others (2002). (1) The backscatter intensity data between 180-220 was stretched to 0-255 (The data published in 2002 between 180-225 was stretched to 0-255). The shaded relief data between 150-200 was stretched to 0-255 (as in the 2002 data). Aging of the multibeam transducer and software changes implemented to correct the near-nadir response make the backscatter intensity observed in 1996, 1998, and 2000 not directly comparable. Further work is needed to match the backscatter intensities between the 1996, 1998 and 2000 surveys. (2) The data were also reprocessed to correct for an error in the UNB software that projected the data on a sphere rather than on the WGS84 ellipsoid. The horizontal error in placement of the data published by Butman and others (2002) was 0 in the northwestern corner of the HARS, and reached about 12 m in the southeastern corner.
All mapped files are in the Mercator projection, having a central longitude of -75 degrees West, a latitude of true scale of 40 degrees north and the horizontal datum is WGS84. The vertical datum is mean lower low water.
Person who carried out this activity:
William Danforth
U.S. Geological Survey
Operational Geologist
384 Woods Hole Road
Woods Hole, MA 02543-1598
USA
508.548.8700x2274 (voice)
508.457.2310 (FAX)
bdanforth@usgs.gov
- Hours_of_Service: 8 a.m. to 5 p.m. EST
No attributes are associated with these data.
These data were navigated with a Differential Global Positioning System (DGPS); they are accurate to +/- 3 meters, horizontally.
These data have been corrected for vessel motion (roll, pitch, heave, yaw) and tidal offsets, and referenced to mean lower low water. The theoretical vertical resolution of the Simrad EM-1000 multibeam echosounder is 1 % of water depth; roughly 30 - 50 cm within the study area. However, the working vertical resolution of the system, is roughly +/- 50 cm.
These data are complete. No further processing and/or modifications will be made to these data.
These data are logically consistent.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints: This information is not for navigational purposes.
Bradford Butman
U.S. Geological Survey
Oceanographer
384 Woods Hole Road
Woods Hole, Massachusetts 02543-1598
USA
508.548.8700x2212 (voice)
508.457.2309 (FAX)
bbutman@usgs.gov
- Hours_of_Service: 8 a.m. to 5 p.m. EST
These data were prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Although all data have been used by the 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.
U.S. Geological Survey Information Services
Box 25286 Denver Federal Center
Denver, Colorado 80225-0046
USA
303.202.4700 (voice)
303.202.4188 (FAX)
- Hours_of_Service: 8 a.m. to 5 p.m. Mountain Time
These data were prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Although all data have been used by the 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.
Brad Butman
U.S. Geological Survey
Oceanographer
384 Woods Hole Road
Woods Hole, MA 02543-1598
508-457-2212 (voice)