The sound speed anomaly of Baltic seawater

The effect of the anomalous chemical composition of Baltic seawater on the speed of sound relative to seawater with quasi-standard composition was quantified at atmospheric pressure and temperatures of 1 to 46 °C. Three modern oceanographic time-of-flight sensors were applied in a laboratory setup f...

Full description

Bibliographic Details
Published in:Ocean Science
Main Authors: C. von Rohden, S. Weinreben, F. Fehres
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2016
Subjects:
geo
Online Access:https://doi.org/10.5194/os-12-275-2016
http://www.ocean-sci.net/12/275/2016/os-12-275-2016.pdf
https://doaj.org/article/3272e7be7ae74b27baa39475147f4a4a
Description
Summary:The effect of the anomalous chemical composition of Baltic seawater on the speed of sound relative to seawater with quasi-standard composition was quantified at atmospheric pressure and temperatures of 1 to 46 °C. Three modern oceanographic time-of-flight sensors were applied in a laboratory setup for measuring the speed-of-sound difference δw in a pure water diluted sample of North Atlantic seawater and a sample of Baltic seawater of the same conductivity, i.e., the same practical salinity (SP = 7.766). The average δw amounts to 0.069 ± 0.014 m s−1, which is significantly larger than the resolution and reproducibility of the sensors and independent of temperature. This magnitude for the anomaly effect was verified with offshore measurements conducted at different sites in the Baltic Sea using one of the sensors. The results from both measurements show values up to 1 order of magnitude smaller than existing predictions based on chemical models.