Surface Drifter Observations From the Arctic Ocean's Beaufort Sea: Evidence for Submesoscale Dynamics

Abstract

AbstractPosition and velocity data are analyzed from a release of surface ocean drifters in the Arctic Ocean's Beaufort Sea in ice‐free conditions. Position information is returned at sufficiently high frequency to allow for the investigation of surface‐ocean flows ranging from around 0.5 km in lateral scale (submesoscale, SM, flows) to flows that are tens of kilometers in horizontal extent. Lagrangian statistics from the drifter release are analyzed in conjunction with Eulerian (ship‐based) measurements of surface ocean temperature and salinity. Results show dynamics that are largely consistent with flows at similar scales in the midlatitude oceans. Horizontal wavenumber k spectra of density in the surface ocean scale as , consistent with energetic SM flows. Lagrangian drifters indicate local dispersion in the surface ocean layer at horizontal scales smaller than 10 km, which confirms the presence of active submesoscale dynamics. Features at these scales give rise to lateral diffusivities (in the range 1–103 m2 s−1) of similar range to values inferred in the midlatitudes. Velocity structure functions present an energy‐cascade inertial range at submesoscales with indication of a transition to a forward energy cascade at scales smaller than 1 km confirming the transition to 3‐D turbulence. The active SM flow‐field drives enhanced lateral and vertical fluxes in the Arctic Ocean mixed layer, which has first‐order implications to the transport of heat, sea‐ice floes, nutrients, and contaminants.