The predictability of acoustic receptions on gliders in the Arctic

Abstract

Acoustic transmissions from shallow sources in the Arctic Ocean can propagate several hundred kilometers due to the presence of an Arctic acoustic duct. Receptions of these long-range transmissions are complex patterns of arrivals which are strongly dependent upon upper ocean sound-speed structure. In addition to measuring sound-speed parameters, gliders equipped with acoustic recorders can measure these arrivals and can complement moored receptions, providing data at many ranges with respect to the moored sources. There is a higher degree of uncertainty in glider position compared with moored receivers, but localization can be improved in post-processing with enhanced acoustic predictability. Two acoustic Seagliders were deployed for a short pilot study in late Summer 2016 in the vicinity of an array of acoustic tomography sources with frequencies on the order of 250 Hz in the Arctic Ocean in anticipation of a longer deployment in Summer 2017. Source receptions recorded on the gliders are compared with acoustic predictions based on sound-speed profiles generated from environmental data collected on the gliders themselves to begin to understand the predictability of transmissions received on gliders in an Arctic environment. Acoustic predictions are analyzed for receptions both within the acoustic duct and at depths exceeding the acoustic duct.