After a small hole is made in the ice (Using the Mora Ice Drill) this CTD is lowered from just under the ice to a depth of 300m at about 0.5 m/s, and samples conductivity, temperature and depth 4 times a second, and records this within the package, allowing the data to be downloaded later to the Onboard Sledge Computer. The measurements are made to a very high accuracy allowing temperature, for example, to be measured to less than 1/1000 of a degree C.

The conductivity, depth and temperature can be combined through a complicated equation based on lab experiments to derive salinity. Temperature and depth allow the water density to be determined. As the vertical CTD profiles are made across the Arctic Basin, the regional changes of these ocean properties will be analyzed. We can, for example, look at the heat available for melting ice, and compare that with high resolution regional ocean models.