Refraction artifacts were minimized by sound velocity profiles throughout the survey area to model the spatial and temporal variability of sound velocity structure of the water column. Changes in vessel draft due to fuel and water usage were not considered.
The RTK signal from repeater station located at Gay Head was not received by the survey vessel for several hours on several days between May 22 and May 29 2010 during USGS Field Activity 2010-004-FA aboard the M/V Megan T. Miller. Earlier attempts to interpolate tide values for missing times were not effective. Instead, USGS requested and received a zone tidal model from the National Oceanic and Atmospheric Administration in December of 2013. Tides were delivered to USGS on 10 Feb and applied only to lines L114F1-L200f1 and including Tie1-Tie10f2 (JD141-JD149). The zone tidal model used verified tides at six minute intervals from three NOAA Tide stations Newport, RI (#84526600), Woods Hole, MA (#8447930), and Nantucket MA, (#8449130). The NOAA Zone Definition File was loaded into HIPS (ver 8.1.6) and merged with Lines L114f1-L200f1.