Mesoscale variability of SOFAR group velocity in the northwest Pacific

Abstract

We present a ray-trace numerical study of the effects of mesoscale structure on the group velocity (defined as the average horizontal ray speed) of deep-refracted acoustic signals using data from a large-scale, near synoptic survey of the thermal structure in the upper 800 m of the Northwest Pacific ocean reported by Emery et al. [W. J. Emery, T. J. Reid, J. A. de Santo, R. N. Baer, and J. P. Dugan, J. Acoust. Soc. Am. 66, 831–841 (1979)]. A representative sample of twelve sound speed profiles (SSPs) from the survey show maximum variation of 10 m/s in the group velocity of a ray with a given J value, J being the phase integral, and illustrate how particular features in the SSPs cause local maxima in the group velocity as a function of J.