Speed of Sound in Seawater Calculator

Compute the speed of sound in seawater from temperature, salinity, and depth using the Mackenzie equation.

Input

Enter water temperature, salinity, and depth to calculate the speed of sound in seawater with the Mackenzie equation.

Water temperature

degC

Seawater temperature. Typical range -2 to 30 degrees.

Salinity

per mille

Per mille. A typical open-ocean value is about 35.

Depth

Depth below the surface. Use 0 for the surface.

Speed of sound in seawater

1,506.692225m/s

Sound takes about 0.663706 seconds to travel 1 km.

Temperature contribution

+57.732225 m/s

Salinity contribution

0 m/s

Depth contribution

0 m/s

Sound speed is fundamental to sonar, depth sounding, and ocean acoustics. In the thermocline it changes with depth.

Uses the nine-term Mackenzie (1981) empirical equation to find the sound speed c from temperature T, salinity S, and depth D.
Approximate valid range: temperature -2 to 30 degrees Celsius, salinity 25 to 40, and depth 0 to 8000 meters.
Each contribution is computed from a baseline state (0 degrees, salinity 35, surface) by substituting temperature, then salinity, then depth in turn.
Salinity is expressed per mille (parts per thousand). A typical open-ocean value is about 35.
Sound speed underpins sonar, depth sounding, and ocean acoustic propagation. In the real ocean the thermocline makes sound speed vary with depth.

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