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Steady rosette

Putting scientific equipment into Arctic waters —such as this conductivity-temperature-depth (CTD) rosette — requires an intricate balance of motion and timing. The shipboard CTD is made up of a set of small probes attached to a large metal rosette wheel. The rosette is lowered on a cable down to the seafloor, and a remotely operated device allows the water bottles to be closed selectively as the instrument ascends. Water sampling is often done at specific depths so scientists can learn what the physical properties of the water column are at that particular place and time. Small, low-powered CTD sensors are used on autonomous instruments like the moored profiler, gliders, profiling floats and AUVs .(Photo by Chris Linder, Woods Hole Oceanographic Institution)