Impact of salinity on predicted transmission loss

Often ocean sound speed profiles are estimated using a temperature profile measured, for example, with an expendable bathythermograph (XBT) combined with a database value for salinity. The prevalence of this approach is due to the added expense and limited availability of sensors that can simultaneously measure both temperature and salinity profiles, for example conductivity-temperature-depth (CTD) probes. When predicting acoustic performance of a sonar system, using the sound speed profile based only on measured temperature is not always sufficient. This study examines when and where the use of temperature-only profiles is adequate as well as potential improvements to typical sound speed profiles that can be made using limited conductivity measurements (i.e. measurement at a single depth or a small segment of the profile) or with database values based on oceanographic models or chosen based on matching the temperature profile rather than the geographically nearest value. The assessment of a profile's ade...