Physical oceanography data from a Seaglider mission north of Svalbard, late fall 2018

The data are collected using a Kongsberg Seaglider in the Arctic Ocean, north of Svalbard in late fall 2018. Quality-controlled, 1-decibar vertically interpolated observations of the water column temperature and salinity in the upper 1000 m, and the depth-average currents (DAC) are provided. The data set is collected as a part of the Nansen Legacy project, funded by the Research Council of Norway (project number 276730). The Seaglider (sg564) was deployed from the RV Kronprins Haakon on 17 September 2018 with a mission planned to collect multiple transects across the warm Atlantic Water boundary current north of Svalbard. Sea ice was avoided. A total of 377 dives (754 profiles) were performed before recovery on 11 November 2018. The Seaglider operated between surface and 1000 m depth, sampling conductivity and temperature on both dives and climbs at a sampling rate of 10 s in the upper 200 m, 20 s between 200 m and 600 m, and 30 s below 600 m. The vertical velocity was normally close to 10 cm/s. The Seaglider was equipped with a Paine strain-gauge pressure sensor, a SBE CT Sail and an Aanderaa dissolved oxygen sensor. Oxygen data are not calibrated, hence not submitted. The data set was processed using the University of East Anglia Seaglider toolbox (http://www.byqueste.com/toolbox.html). Hard limits on salinity and temperature were applied to exclude obvious outliers and data gaps were then linearly interpolated. Outputs from the toolbox are separated into dive and climb profiles, organized starting from the surface, and vertically interpolated at a regular 1-db interval. Each data point in the profile also has the corresponding time and position. Temperature at ITS-90 scale and salinity at the practical salinity scale are submitted for archiving. Processed practical salinity and temperature are accurate to 0.01 and 0.001C, respectively, and DAC is accurate to 0.01 m/s. Data spikes above three standard deviations, for each pressure level over all profiles, were removed during post-processing. Finally, a salinity offset of +0.005 was applied after comparing the deep part of the Seaglider dives (750 m to 1000 m) to nearby CTD profiles (within 7 days and 15 km) collected from the RV Kronprins Haakon (cruise KH2018709). No correction on temperature was necessary.