Natalie Cook
Master’s Thesis Defense
Ocean Engineering: Ocean Mapping
Monday, September 14, 2026, 12:00pm
Chase 130
Abstract
Measurements from swath mapping sonar systems must be corrected for acoustic refraction that results from variation in sound speed, which changes with water temperature, salinity, and depth. A Conductivity Temperature Depth (CTD) cast is usually taken every 2 to 4 hours to provide the vessel’s system the necessary measurements to accurately return the seafloor depth. However, conducting these casts often introduces operational delays and, when performed from uncrewed surface vehicles operating far from shore or shipboard support, carries inherent risks to the mission. An alternative to taking casts for physical water characteristics is the derivation of synthetic casts from the NOAA/National Ocean Service 3D forecast systems. Designed to predict storm surge, these operational forecast systems produce nowcasts that generate predictions of the present sea conditions as well as forecasts going multiple days into the future. While never identical to the real conditions, these nowcasts and forecast guidance can give input on physical ocean characteristics and how they can evolve over time. This study compares observed CTD casts in the Gulf of Maine to the spatially and temporally closest nowcast and forecast guidance from the 3D Surge and Tide Operational Forecast System (STOFS-3D-ATL) to determine whether the model-generated sound speed profiles can correct swath mapping sonar data for acoustic refraction in lieu of observed casts. This benefit of using STOFS-3D-ATL-derived casts is reduced cast frequency on uncrewed vessels to allow increased mapping coverage and to lessen risk of equipment malfunction.
Bio
Natalie Cook graduated from the University of New Hampshire where she earned her B.S. in Ocean Engineering. As an undergrad, Natalie spent time aboard NOAA Ship Thomas Jefferson where she learned all about hydrography and began to tailor her undergrad curriculum towards the field. She worked with CCOM's Autonomous Surface Vehicle (ASV) lab during the summers and decided to continue her education where her interests lie—in robotics and mapping. Currently, she is pursuing an M.S in Ocean Engineering: Ocean Mapping with the ASV team, and looks forward to learning more about applications of marine robotics for hydrography while working on her programming skills.
