Agenda Session

Underwater gliders deliver sustained ocean measurements via low power consumption, allowing for broad spatial and temporal coverage. The suite of flight and science sensors carried by most gliders allow for a myriad of analyses. Highlighting a non-traditional use of the altimeter, a flight sensor, the compilation of single-beam soundings from repeated transects over multiple missions can be interpolated to produce a coarse map of the seafloor. In an initial comparison, the interpolated bathymetry created from glider soundings was often within 1 to 2 meters of the seafloor depths generated by a shipboard multibeam system for the study area. The multibeam data was reprojected to match the coarser resolution of the glider data. The method for processing and correcting the glider data is nearly finalized and Glider Derived Bathymetry (GDB) for a large portion of the Central West Florida Shelf (CWFS) has been interpolated to 100-meter resolution for consideration by coastal seabed mapping initiatives and as a tool to aid higher resolution mapping efforts. In addition to a standalone, reconnaissance product like GDB, gliders can directly contribute to traditional surveys by enhancing the sound field data collected in the vicinity of surface vessels mapping the seafloor with high-resolution multibeam echosounders. This scenario was tested on the CWFS in the fall of 2023, with two gliders sending near-real time sound speed profiles to a nearby research vessel acquiring high-resolution seafloor data. The method awaits further implementation on future projects. In the spring of 2025, the USF glider group coordinated with the Ocean Mapping division of Saildrone, who were tasked with mapping the Florida Middle Grounds on the West Florida Shelf. Co-locating a glider in the vicinity of two drones mapping in the target area coincided with acquiring model output data from the USF Ocean Circulation Lab. Preliminary comparisons have been made between in-situ glider sound speed profiles derived from CTD output and model sound speed profiles derived from modeled salinity, temperature and depth, extracted from the West Florida Coastal Ocean Model at specific nodes in the region of interest. This project asks the question:  how can physical oceanographic models alone, or in tandem with autonomous underwater vehicles, be used to augment the sound fields acquired for seafloor mapping? Bathymetry derived by or enhanced by non-traditional means will likely represent an increasing portion of seafloor products in the future. As for the role of gliders, specifically, the suite of sensors typically integrated within their payload designates these vehicles as value-added assets for subsea mapping and exploration.