Helicopter CTD – transportable CTD with autonomous winch

Fig. 1: A-frame with CTD and 5-l bottle. The support gear near the edge hosts the frame and spreads the mechanical forces. (Photo: Dr. Michael Schröder, AWI)

High resolution profiles of typical physical parameter of seawater such as temperature, conductivity/salinity, and pressure can only be measured in the water column, including the bottom boundary layer, by means of a single wire cable.

In ice covered regions this is only possible aboard a ship or from an ice floe.

The latter requires autonomous instrumentation able to handle long cable lengths to reach the bottom. In shelf areas of less than 500 m deep water but also for greater depth along the continental shelf break full-depth data acquisition needs a cable length of more than 1500 m.

Such self-sustaining system has the advantage of being independent from ship operations and gives a wider range for data collection not consuming expensive and rare ship time. This is even more important, when the ship is immoveable due to heavy ice conditions.

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