CTD

Conductivity, Temperature and Depth

A Profiling CTD measures water parameters as it travels through the water, whether lowered over the side of a ship with a winch to take measurements of a vertical column of water or integrated with an autonomous vehicle or glider. Common to all Sea-Bird Profiling CTDs:

• Purposeful designs built to perform under the unique dynamic conditions found on varying measurement platforms

• Pumped and ducted constant flow for matched temperature and conductivity response

• Measurements are made on the same sample of water with a predictable delay and predictable flow effects

• Aligning and coordinating measurements done with software or (for some models) automatically


Profiling CTDs can also be deployed in many ways other than being lowered and raised from a ship. They can be integrated with an autonomous vehicle like an ROV (Remotely Operated Vehicle), a glider, or an Argo float that drifts with the currents. The type of vehicle and characteristics of its use dictates the CTD design that will provide the best data; CTDs are not one-size-fits-all instruments, if you are interested in good data. Because some of these CTDs are deployed for an extended period of time (3 to 5 years for an Argo float!), they are subject to fouling – the growth of marine organisms on and inside the sensors. Fouling is more common in warm surface waters. Sea-Bird uses EPA-approved anti-foulant devices to keep the inside of the sensors clean, so that fouling will not affect the measurements.

The SBE 911plus CTD is the primary oceanographic research tool used by the world’s leading institutions, providing 24 Hz sampling with an SBE 9plus CTD Unit and SBE 11plus V2 Deck Unit. The 911plus system provides real-time data collection over 10,000 meters of cable. The 911plus’ pump-controlled, T-C ducted flow minimizes salinity spiking caused by ship heave and allows for slow descent rates without slowing sensor responses, improving dynamic accuracy and resolving small scale structure in the water column. The 911plus supports numerous auxiliary sensors (dissolved oxygen, pH, turbidity, fluorescence, oil, PAR, nitrates, altimeter, etc.) with eight A/D channels.

Source: Seabird.com