Abstract:

This data is the boundary polygon for the high-resolution bathymetric measurements of the seafloor from Boston Harbor and the harbor approaches, Massachusetts. Approximately 170 km² of sidescan sonar and bathymetric data were collected by the National Oceanic and Atmospheric Administration (NOAA) Ship Whiting in 2000 and 2001 and reprocessed and gridded by the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS).

Purpose:

The geophysical dataset were collected by the National Oceanic and Atmospheric Administration (NOAA) National Ocean Service (NOS) branch as part of their periodic hydrographic mapping for nautical charting. The raw datasets were provided by NOAA to the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS) in Woods Hole, MA as part of a cooperative agreement to provide high resolution bathymetry and backscatter intensity maps and digital GIS information for resource management, scientific research, industry and the public.

Currentness reference:

ground condition

Use constraints:

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.

Address:

384 Woods Hole Rd.

Logical consistency report:

No additional checks for topological consistency were performed on this data.

Horizontal positional accuracy report:

All of the NOAA survey vessels were equipped with Trimble DSM212L Differential Global Positioning System (DGPS) receivers.  Launch 1005, which collected all of the multibeam bathymetry, was also equipped with a TSS POS/MV Model 320 (Position and Orientation System for Marine Vessels).  Standard bathymetric processing, including tide corrections, soundings accuracy, and quality control were done by the NOAA Office of Coast Survey.

Vertical positional accuracy report:

Tidal datum for this project is Mean Lower Low Water (MLLW).  The tide station at Boston, MA (844-3970) was the control for the vertical datum.

Source contribution:

The original geophysical data for this project were collected during four hydrographic surveys conducted by NOAA NOS in 2000 and 2001 on the NOAA Ship Whiting and its launches 1005/1014.  Multibeam bathymetric data were acquired with a Reson SeaBat 8101 and sidescan sonar backscatter data were acquired with Edgetech model 272-T (100 kHz) or the Klein T-5500 (455 kHz) sonar systems.

Process description:

A hull-mounted Reson SeaBat 8101 acquired the shallow-water multibeam data for all four surveys.  The Reson 8101 was operated at a frequency of 240 kHz and a maximum speed of 6 knots.  The system is designed for operation in water depths of 5 to 125 m, and has a horizontal range of 75 to 500 m that depends on water depth.  Each time the system fires or "pings", it collects 101 individual soundings in a swath oriented perpendicular to the vessel track.  Acquisition was monitored in real time with the ISIS software (version 5.29) and recorded to XTF format.  NOAA Office of Coast Survey converted the XTF data to CARIS HDCS (Hydrographic Data Cleaning System) format, then processed and tide-corrected the data with CARIS HIPS (Hydrographic Information Processing System) software. The CARIS HIPS database was transferred to the USGS/CZM in 2004 for use in this project.

Process description:

Tide-corrected multibeam soundings were exported from CARIS HIPS at a 2-meter grid interval for each of the survey areas and reformatted for input into the Swathed processing software (University of New Brunswick Ocean Mapping Group).   The soundings were gridded using the weigh_grid routine creating 2-meter bathymetry grids.  The OMG grid format (.r4) was converted to ASCII raster format.

Address:

c/o U.S. Geological Survey

Address:

384 Woods Hole Rd.

Process description:

The ASCII raster format files were each imported to ArcGIS 9.0 using ArcToolbox ("ASCII to Raster") and then merged to create a master grid of multibeam bathymetry.

Address:

c/o U.S. Geological Survey

Address:

384 Woods Hole Rd.

Process description:

In ArcMap (Spatial Analyst -> Raster Calculator) evaluated the expression "bh_2mmbbath > -32" the resulting was a temporary file 'calculation' with value = 1 where the multibeam data exists.  In ArcMap (Spatial Analyst -> Convert -> Raster to Features) the temp grid 'Calculation' was converted to a polygon shapefile (Input raster: Calculation, Field: Value, Output geometry type: Polygon).

Address:

c/o U.S. Geological Survey

Address:

384 Woods Hole Rd.

*Attribute definition:

Internal feature number.

*Attribute definition source:

ESRI

*Attribute definition:

Feature geometry.

*Attribute definition source:

ESRI

Attribute definition:

Multibeam area id number

Attribute definition:

Area of feature in meters squared.

*Attribute definition source:

ESRI

Address:

c/o U.S. Geological Survey

Address:

384 Woods Hole Rd.

Distribution liability:

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.

Format specification:

ESRI Polygon Shapefile

Address:

c/o U.S. Geological Survey

Address:

384 Woods Hole Rd.

multibeambathybnds: Multibeam Bathymetry Boundaries from Boston Harbor and Approaches
	Data format: Shapefile File or table name: multibeambathybnds Coordinate system: Universal Transverse Mercator Theme keywords: U.S. Geological Survey, USGS, Coastal and Marine Geology Program, CMGP, Woods Hole Science Center, WHSC, Massachusetts Office of Coastal Zone Management, CZM, Seafloor, Marine Geology, ESRI Shapefile, field activity serial number RAFA04019, Multibeam, Bathymetry, Reson SeaBat 8101, Reson, Topography, National Oceanic and Atmospheric Administration, NOAA, National Ocean Service, NOS, NOAA Ship Whiting, Hydrographic Survey, 32-bit floating point, oceans and estuaries, elevation, boundaries
Abstract: This data is the boundary polygon for the high-resolution bathymetric measurements of the seafloor from Boston Harbor and the harbor approaches, Massachusetts. Approximately 170 km² of sidescan sonar and bathymetric data were collected by the National Oceanic and Atmospheric Administration (NOAA) Ship Whiting in 2000 and 2001 and reprocessed and gridded by the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS).

FGDC and ESRI Metadata: