Pressure dependence of sound absorption in synthetic seawater at 0 °C

Measurements have been made of sound absorption in Lyman and Fleming seawater at 1 and 307 atm. Results for maximum absorption per wavelength (αλ)_max/10⁶ are 45.8 ± 0.4 at 1 atm and 28.9 ± 0.6 at 307 atm. The relaxation frequency of ∼39 kHz appears to be independent of pressure as had been observed earlier at 25 °C. Our results are in excellent agreement with the predictions of Francois and Garrison for 0 °C for both sound absorption and relaxation frequency. Based on these results together with the earlier ones at 25 °C reported by Hsu and Fisher [J. Acoust. Soc. Am. 74, 564–569 (1973)], we find a temperature dependence for both absorption and relaxation frequency different from that reported by Francois and Garrison. These differences will be discussed. The following equation represents our results for absorption (s = ± 0.8): (αλ)_max/10⁶ = 45.6 + 0.652(t/°C) − 0.0533(P/atm). [Work supportedby the Office of Naval Research, Code 400R.]