The West Spitsbergen Current as seen by SOFAR floats during the ARCTEMIZ 88 Experiment: Statistics, differential kinematic properties, and potential vorticity balance

Abstract

SOFAR Floats were launched at 300 m depth in the West Spitsbergen Current (WSC) in September 1988. This Lagrangian data set is used to compute statistical parameters; to produce local maps of mean velocity, kinetic energy, and eddy kinetic energy; and to study dispersion and diffusion in the WSC. Despite the limited number of float trajectories, the values obtained for the diffusivities, order 1.0 × 107 cm2 s−1, are close to those found in other regions of the Atlantic Ocean. The Molinari and Kirwan [1975] method is used to compute the differential kinematic properties (divergence, vorticity, shear, and stretching). The conservation of potential vorticity in the region of the Yermak Plateau is not correctly verified; this is mainly due to the jet structure of the WSC and the shape of the cluster, leading to a biased estimate of the relative vorticity. However, the results (based only on five float trajectories over 30 days) are encouraging and not inconsistent with the properties of the West Spitsbergen Current. The existence of a new eastward branch of the WSC, passing just over the top of the Yermak Plateau, is confirmed.