This dataset comprises of data from stainless steel and titanium CTD casts and towfish, results of a nutrient addition incubation experiment, and underway meteorological, hydrographic, and navigational data. The CTD casts and towfish were sampled for biogeochemical properties: nitrate + nitrite, silicate, phosphate, nitrite, d18O, dissolved oxygen, chlorophyll-a, particulate carbon, carbon fixation rates and oxygen isotopes. The CTD casts also comprise of downcast sensor profile data and upcast sensor data at time of bottle firing: temperature, salinity, density, dissolved oxygen, optical backscatter, beam transmittance and attenuation, upward photosynthetically active radiation (PAR), and chlorophyll-a fluorescence. The underway sensor data are sea surface hydrography (temperature and salinity), optical (chlorophyll-a fluorescence, transmission) and meteorological (wind speed and direction, air temperature, air pressure, relative humidity PAR, TIR). The nutrient addition experiments were sampled for Nitrate+nitrite, phosphate, silicate, chlorophyll a, and Fv:Fm after addition of nitrate, phosphate, and/or iron chloride. All of the data were collected during cruise DY167 (GEOTRACES cruise GApr19) in July-August 2023 from Southampton up to the Norwegian and Barents Seas and cover the relatively warm Atlantic Water inflow, fresher water on the Spitzbergen Bank, coastal/glacial outflow around Svalbard, and Arctic water around sea ice. These data were collected to better determine how temperature, light, nutrients, and iron control the distribution and activity of nitrogen fixing organisms in the Arctic Ocean. This dataset was generated by the National Oceanography Centre (NOC), the University of Liverpool (UoL), and the University of Southampton, under Natural Environment Research Council (NERC) Discovery Science grant "Nitrogen fixation in the Arctic Ocean", N-ARC (grant numbers NE/T000570/1 and NE/T001240/1).
