Helicopter CTD – transportable CTD with autonomous winch

Therefore AWI decided to develop a special device, which can be carried by a helicopter (type BO-105) as outside payload to ice floes. The operation radius around the ship is up to 100 km. The only requirements are stable ice floes more than 0.5-m thick and some open leads around to lower the instrument. The latter saves drilling devices and thus space and weight during the air lift.

Fig. 2: Flying with the total pay load. To shelter the system all components are covered by a tarpaulin. 
(Photo: Dr. Michael Schröder, AWI)



Fig. 3: Dropping off the system at the edge of an ice floe.
(Photo: Dr. Michael Schröder, AWI)

The latter saves drilling devices and thus space and weight during the air lift. The rack consists of a special lift-off frame, which combines two aluminum sledges, carrying the generator and the mobile winch. The whole system weighs 525 kg.

The instrument rack includes a CTD-probe, an altimeter, and up to two 5-liter bottles, which can be fixed to the cable and closed by a messenger. This allows for tracer sampling in the bottom layer.

The CTD probe is a Seabird 911 plus with double sensor pairs for temperature and salinity to achieve the same accuracies as the ship system.

After intensive flight tests in Bremerhaven, this equipment was first used successfully during the international drift experiment ISPOL (2004-2005) in the western Weddell Sea. Here, the outflow of very cold shelf waters from the Larsen ice shelf into the deep basin of the Weddell Sea was observed (https://www.researchgate.net/publication/222531875_The_ISPOL_drift_experiment)

Fig. 4: 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)

Fig. 5: Helo-CTD with A-frame in measuring mode.
(Photo: Dr. Michael Schröder, AWI)

Fig. 6: Fully assembled measuring system, consisting of a tent, a winch, and an A-frame. Inside the tent a laptop computer samples the data while the CTD-probe descend. The A-frame can be lifted up and down to move the instrument over the ice floe edge.

It can be dismantled into 4 pieces of 1.2 m length each. The generator is located in the back (not seen on the picture).
(Photo: Dr. Michael Schröder, AWI)

Fig. 7: Complete helo-CTD-station seen from above the air.
(Photo: Dr. Michael Schröder, AWI)