Stable water isotopes of seawater samples from the MOSAiC expedition 2019/2020.

Seawater samples for stable oxygen water isotopes (delta 18 O) were taken during leg 1-5 of the MOSAIC expedition either from the Ocean City (OC CTD) on the main MOSAiC ice floe or from the shipboard CTD (PS CTD). Analysis for delta 18 O where conducted at the Leibniz Laboratory (LLK, Kiel, Germany) with mass-spectroscopy, applying the CO2- water isotope equilibration technique on at least 2 sub-samples on a Finnigan gas bench II unit coupled to a Finnigan DeltaPlusXL. A subset of stations were analyzed at AWI and published separately as Mellat et al. 2023 (https://doi.org/10.1594/PANGAEA.958464).