CTD casts were performed at the Kamb Ice Stream site 3 borehole (-82.6285, -156.3046). These data target a major subglacial outlet river emerging from beneath the Kamb Ice Stream. These data were used to determine both the role of water beneath the ice sheets and the ice-ocean interactions that take place once this water emerges into the ice shelf cavity.
Four instruments were used for oceanographic profiling: two RBR Concerto CTDs that measure conductivity, temperature, and pressure, and two RBR Duets that measure temperature and pressure. The inductive salinity cells in the Concerto profilers were positioned at least 15 cm away from conductive material except during CTD casts 3 and 4, when the Concertos were placed inside the metal frames. A standard profiling technique was used for each CTD profile, with slow deployment through the upper part of the ice hole and the base of the ice shelf and descent to within ~3 m of the seafloor to allow equipment to equilibrate for a minimum of 15 minutes. To avoid the winch cable freezing into the ice hole, the cable was moved whenever the instruments were stationary for more than ~30 seconds to 1 minute. This was done either by nudging the winch up and down a very small amount or by manually leaning on the exposed winch cable between the pulley mast and the winch. After remaining at the seafloor for 15 minutes, the instruments were raised up into the base of the ice shelf briefly, and then lowered again to near the seafloor. This procedure was repeated using varying speeds until the end of the cast (‘jojo-ing’), attempting to not exceed a speed of ~0.5 m/s. The final CTD cast was operated for 24-hours to capture a full tidal cycle
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