Oxygen isotope water samples (seawater, sea ice, meltwater pools) collected on JR15006, March-April 2016.

This dataset consists of δ18O and salinity data from samples collected onboard the RRS James Clark Ross JR15006 cruise on behalf of the ORCHESTRA project during March-April 2016. Samples were collected from CTDs, the underway supply and ice/meltwater/shore water using small boats. The cruise consisted of the semi-annually repeated A23 hydrographic CTD section between the Weddell Sea and South Georgia, combined with the opportunistic request for 6 extra science days to take advantage of the newly installed oxygen isotope auto-analyser connected to the ship's underway system. The goal of this extension was to collect 'end member' samples of oxygen isotopes from freshwater input to the region in order to attribute the freshwater component of underway observations to various percentage contributions from (for e.g.) sea ice melt, precipitation, glacial outflow etc. In addition, oxygen isotopes were collected from CTDs on both A23 and in the vicinity of strong freshwater input, to establish the mixing between deep ocean interior values and local surface sources.