CTDs

CTDs measure how the electrical conductivity and temperature of the water column changes relative to depth. Conductivity and temperature information is valuable because the speed of sound in seawater can be derived from these variables. This is used to correct devices that use sound underwater. CTD data can also be used to calculate water density. Oceanographers use CTDs to study the physical properties of water which can help them understand currents, mixing, biological processes and other phenomena. For this reason they are one of the most common instruments used by marine scientists.

CTDs may be deployed by itself, attached to a submersible, or as part of a larger metal water sampling array known as a rosette, or carousel. Multiple water sampling bottles are often attached to the rosette to collect water at different depths of the cast.

For commercially available CTDs click here.

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