# Speed of sound in sea water (UNESCO equation)

## Description

The speed of sound is the distance travelled per unit of time by a sound wave propagating through an elastic medium. The speed of sound in seawater depends on pressure , temperature (a change of 1 °C ~ 4 m/s), and salinity (a change of 1‰ ~ 1 m/s). Empirical equations have been derived to accurately calculate sound speed from these variables. One of them with reasonable accuracy for the world’s oceans often known as UNESCO equation is due to Chen and Millero (1977)

Related formulas## Variables

c_{SeaWater} | Speed of sound (dimensionless) |

C_{W} | Empirical coefficient (must be precalculated) (dimensionless) |

A_{TP} | Empirical coefficient (must be precalculated) (dimensionless) |

S | Salinity in Practical Salinity Units - ppt (dimensionless) |

B_{TP} | Empirical coefficient (must be precalculated) (dimensionless) |

D_{TP} | Empirical coefficient (must be precalculated) (dimensionless) |