Further evidence that the sound-speed algorithm of Del Grosso is more accurate than that of Chen and Millero Available to Purchase

Estimates of the bottom depth of the ocean at 11 sites were determined by combining round-trip acoustic travel time measurements made by inverted echo sounders on the ocean bottom with sound-speed profiles determined from simultaneously measured temperature and salinity profiles. These depths were converted into pressures and were compared to independently measured bottom pressures to determine the accuracy of the algorithms used to calculate the sound-speed profile. The sound-speed algorithms tested were those derived by Del Grosso [J. Acoust. Soc. Am. 56, 1084–1091 (1974)] and by Chen and Millero [J. Acoust. Soc. Am. 62, 1129–1135 (1977)], as well as the corrected version of Chen and Millero’s algorithm recently published by Millero and Li [J. Acoust. Soc. Am. 95, 2757–2759 (1994)]. The results of this study agree with the results from recent acoustic tomography experiments which indicate that the algorithm of Del Grosso for the speed of sound in seawater is more accurate than the currently accepted standard algorithm of Chen and Millero. Del Grosso’s algorithm also produces more accurate results than those from the Millero and Li correction to the Chen and Millero algorithm.