Classification of Barents Sea water masses from cruise DY167 (RRS Discovery) in July-August 2023 using Optimum Multiparameter (OMP) analysis

These data files provide the results of an Optimum Multiparameter (OMP) analysis applied to water samples collected from the Barents Sea during research cruise DY167 in July-August 2023 on the RRS Discovery. By solving a set of overdetermined linear equations an OMP analysis estimates the relative contributions of different water masses within a water sample. Here, we consider five water-mass endmembers: Atlantic water (AW), warm Atlantic water (wAW), Arctic water (ArW), warm Arctic water (wArW), and a glacier-influenced water mass (GW). Each end-member was defined using six hydrographic and biogeochemical tracers: conservative temperature (CT), absolute salinity (SA), silicate (Si), nitrate + nitrite (NN) alongside the meteoric (Fmet) and sea-ice melt fractions (Fsim) of seawater derived from oxygen isotope analysis. A total of 122 samples with all 6 tracers were used in the OMP. Of these, 94 samples were collected between 5 and 360 m depth from a stainless steel CTD rosette (Mahaffey 2026a) and 28 samples were collected from a trace-metal free FISH towed behind the ship at an average depth of 3 m (Mahaffey 2026b). References: Mahaffey C.; Fisher B.J.; Wrightson L.; Hopkins J.; Arrowsmith C.; Sanders R.N.C.; Meredith M.P.; Barton B.I.; Henderson P.; Rynders S.(2026a). Stainless Steel CTD water column samples (macronutrients, chlorophyll-a, particulate carbon, C-fixation, d18O) and upcast sensor measurements (temperature, salinity, oxygen, optical backscatter, beam transmittance and attenuation, PAR, fluorescence) from cruise DY167 (GApr19), July-August 2023. NERC EDS British Oceanographic Data Centre NOC. doi:10.5285/48e39c93-2405-99f3-e063-7086abc003fa Mahaffey C.; Norman L.; Fisher B.J.; Wrightson L.; Lohan M.; Hawley R.; Flanagan O.; Hopkins J.; Rynders S.; Arrowsmith C.; Sanders R.N.C.; Meredith M.P. (2026b). Underway biogeochemical samples data (macronutrients, chlorophyll-a, dissolved trace elements, particulate carbon, carbon fixation, d18O) and water mass fractions from a towfish at 3 m in the Norwegian and Barents Sea on cruise DY167 (GApr19), July-August 2023. NERC EDS British Oceanographic Data Centre NOC. doi:10.5285/48d50e6a-e137-e1e3-e063-7086abc09a72