A multi-platform observational campaign to investigate sea level, currents, and thermohaline properties near the shelf break was conducted SW of Spitsbergen in early autumn 2019. Using moored and mobile instruments, we captured variability on timescales between 12 hours and a few days with high spatial resolution. Sea level estimates revealed dominant semidiurnal tidal constituents, with amplitudes up to 84 cm. Acoustic Doppler current profiler and drifter data confirmed the presence of the West Spitsbergen Current along the slope but also highlighted weak SE-ward mean currents on the shelf. Tidal currents, particularly the M2 and K1 constituents, accounted for a large portion of velocity variance, with cross-shelf transport indicated by low-eccentricity tidal ellipses. Water column structure showed baroclinic tidal flows, with depth-dependent current variations and the presence of an internal tide. Drifter data confirmed enhanced near-surface variability, likely influenced by near-inertial motions. High-frequency thermohaline measurements from a Wirewalker profiler revealed a periodically varying mixed layer, pronounced internal tide signatures, and dynamic interactions between colder, fresher Arctic Water and warmer, saltier Atlantic Water across the polar front. Glider observations confirmed these thermohaline structures and further highlighted the spatial complexity induced by tidal modulation and fine-scale interleaving of the two water masses.
On the currents and water masses on the shelf break SW of Spitsbergen
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