Support USGS
2007
W00486
Massachusetts
Massachusetts Coastline
Duxbury to Hull
2006-08-04
2007-05-02
ESD-PHB-19
US Geological Survey
Walter Barnhardt, Seth Ackerman, Brian Andrews, Wayne Baldwin
Interferometric
SEA
SwathPlus-M
Pacific Hydrographic Branch
meters
Any revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/.
Products created during office processing were generated in NAD83 UTM 19N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.
North American Datum 1983
Mean Lower Low Water
Discrete Zoning
Projected UTM 19
2019-11-21
CC BY (External Source Data)
CC-BY-4.0
https://creativecommons.org/licenses/by/4.0/
https://creativecommons.org/licenses/by/4.0/legalcode
This data is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0). Attribution is included in this report.
2019-11-21
Pacific Hydrographic Branch
Walter Barnhardt, Seth Ackerman, Brian Andrews, Wayne Baldwin
US Geological Survey
Woods Hole Coastal and Marine Science Center
PHB
The US Geological Survey (USGS) and the Massachusetts Office of Coastal Zone Management (CZM) cooperated to map approximately 200 km² of the Massachusetts inner continental shelf between Duxbury and Hull during three cruises between 2006 and 2007.
The USGS dataset includes interferometric sonar data gridded at 5m resolution. USGS performed an iterative interpolation process in order to create a more seamless grid without visible data gaps. For navigational charting purposes it is preferable to use un-interpolated surfaces that preserve data gaps, particularly over shallow areas. An un-interpolated surface (SouthShore_June23) was located in the USGS data. This un-interpolated surface was used to create archival and charting products under the W00486 label.
The original USGS surfaces included data from NOAA survey H10993. This data was removed from the bathymetric surfaces for archival but was utilized to review and evaluate the data for navigational charting purposes.
Navigation was based on a Real-Time Kinematic Global Positioning System (RT-GPS). The RT-corrected GS signal was sent to the ship from a base station established by USGS on land. Soundings were referenced to MLLW using orthometric to chart datum offsets obtained from NOAA Tidal Station #8446009 at Brant Rock Harbor, MA.
All survey systems and methods utilized during this survey were as described in USGS Open-File Report 2009–1072, "Geophysical and Sampling Data from the Inner Continental Shelf: Duxbury to Hull, Massachusetts".
During office review the USGS survey data was compared to other sources of overlapping data from the National Bathymetric Source (NBS). This comparison was used in two ways. First, it was found that W00486 is approximately 0.44 meters deeper than overlapping data, which indicates a systematic bias that is common for interferometric systems. To mitigate the systematic bias, a 0.44-meter vertical shift was applied to the data per Hydrographic Surveys Division's vertical shift policy. Secondly, the NBS comparison was used to estimate the vertical uncertainty of the USGS data. Through a statistical analysis, the reviewer determined that a calculated uncertainty layer of 2m + 5% of Depth would capture the 2-sigma standard deviation (95% confidence interval) of the difference values between the USGS data and overlapping source data in the NBS.
All data were reviewed for DTONs and none were identified in this survey.
US Geological Survey
https://pubs.usgs.gov/of/2009/1072/
The survey is partially adequate to supersede previous data.
This survey does not meet feature detection requirements and has numerous gaps in coverage. It is recommended to retain all charted features within the survey area.