Depth contours derived from swath bathymetry data collected in Buzzards Bay by the U.S. Geological Survey and the National Oceanic and Atmospheric Administration offshore of Massachusetts in 2004, 2009, 2010, and 2011 (BB_5mCntr Esri Polyline Shapefile, Geographic, WGS84).

NOAA Hydrographic survey H11319: NOAA's National Ocean Service Hydrographic Surveys Specifications and Deliverables closely follow the International Hydrographic Organizations Standards for Hydrographic Surveys, Reference tests conducted in the summer 2004 showed that the NOAA Ship RUDE's sonar system exceeded the International Hydrographic Organization's "Special Order" specification. Position and attitude on the NOAA Ship Rude was measured using TSS POS/MV 320 and a Trimble DSM-212L DGPS receiver. A SeaBird SBE 19 SEACAT conductivity, temperature and depth (CTD) profiler was used to measure sound-velocity data. The tidal datum for survey H11319 is Mean Lower Low Water (MLLW). Tidal corrections were calculated using verified data from tidal station #8452660 at Newport, RI, and final corrected soundings (from a zoned tidal model) were referenced to MLLW (NOAA DAPR, 2004; NOAA DR, 2004). Refer to the NOAAShipRUDE2004 Data Acquisition and Processing Report (DAPR) and the Horizontal and Vertical Control Report in the Descriptive Report, for detailed equipment, vessel configuration and setting information. USGS field activities 2009-002-FA, 2010-004-FA and 2011-004-FA: Vertical accuracy of the raw data based on system specifications may approximate 1% of water depth, 0.10.4 meters within the survey area. However, overall vertical accuracies on the order of 50cm or more are assumed based on the following considerations: The Coda Octopus F180 Attitude and Positioning system was used to correct for vessel roll, pitch, heave, and yaw, which has a theoretical vertical accuracy of a few mm. Tidal offsets were corrected to MLLW using Real-Time Kinematic GPS (RTK-GPS) heights in post-processing (see process steps). Corrections were sent via cellular modem and VHF radio to the ship from the base station on land. The primary reference station is located at the USGS Marine Operations Facility (MOF) in Falmouth, MA. Field tests using submerged targets suggest that the vertical accuracy of the RTK-GPS tidal correction is less than 30cm. Refraction artifacts were minimized by acquiring a range of sound velocity profiles with a hand-casted Applied MicroSystems SV Plus sound velocimeter during survey 2009-002-FA and an ODIM MVP30 moving vessel profiler during surveys 2010-004-FA and 2011-004-FA. Sound velocity data are entered into the SWATHPlus acquisition software to model the sound velocity structure of the water column. Gridding algorithms and cell sizes for these data could introduce errors as great as 3m along the edges of the data, but gridding-induced errors are likely much smaller (less than 20cm) for most of the survey area. Changes in ship draft due to water and fuel usage were not considered.