Every sonar system, underwater survey, and subsea operation depends on knowing how fast sound travels through the water — and that number is never constant.
The speed of sound in seawater changes with depth, mainly because of temperature, and also salinity and pressure. This change with depth is the sound speed profile (SSP), a basic input for almost every underwater acoustic system.
The SSP keeps changing with time, weather, and location, sometimes within the same day.
Two profiles measured one day apart at the same site.
Sound speed is an input to most work on and under the water.
Sonars convert echo travel time into range and depth using sound speed. A wrong sound speed means wrong positions.
Sound speed affects streamer positioning and the accuracy of seismic images.
Acoustic positioning for vessels, ROVs, and subsea work depends on accurate sound speed.
Sound speed is closely tied to temperature, making it useful data for ocean and climate studies.
A wrong sound speed can move where a system thinks something is.
Targets appear blurred or in the wrong place.
Neighbouring survey lines disagree, creating false ridges and steps that need cleanup or re-survey.
Sound bends through water layers. With the wrong profile, that bending is misjudged and images are misaligned.
Positioning accuracy drops as the water changes and sound speed data goes out of date.
Sound speed needs to be measured often, not once per survey. Today's tools either stop the vessel, cost a lot, or are single-use.
Atlantic Echo is built to provide frequent, underway sound speed data without that cost and disruption.