Effects of range-dependent sound speed on acoustic seaglider arrivals in the Canada Basin

Two seagliders equipped with temperature, conductivity and pressure sensors, acoustic recorders, and acoustic Doppler current profilers were deployed in the Canada Basin as part of a large scale acoustic tomography experiment in the summer of 2016 and 2017. The seagliders received transmissions from moored acoustic sources transmitting linear frequency modulated sweeps with 100 Hz bandwidth and center frequencies on the order of 250 Hz. Sources were moored at approximately 175 m depth within an acoustic duct (sometimes referred to at the Beaufort Duct), which is present in the Canada Basin due to Pacific Winter Water, enabling acoustic transmission to long ranges. Acoustic Seagliders recorded transmissions at ranges up to 480 km. The variability and stability of the acoustic duct with range was measured by temperature and salinity profiles recorded by the gliders as they transited between moored source locations. The range dependence of this duct will be explored through oceanographic measurements made in...