2011-03-09 09:47:05

The CTD Rosette. The CTD is an electronic instrument used in oceanography to collect water samples and record salinity (by measuring conductivity), temperature, and depth (by measuring pressure). The instrument is lowered on a hydrowire from the ship. Each cylinder (Niskin bottles) has lids at both ends. They are sent down open, and triggered to close electronically at the depth that water needs to be collected. This way, water can be sampled at many different depths throughout the water column.