Articles | Volume 10, issue 6
Research article
28 Nov 2014
Research article |  | 28 Nov 2014

The Rossby radius in the Arctic Ocean

A. J. G. Nurser and S. Bacon

Abstract. The first (and second) baroclinic deformation (or Rossby) radii are presented north of ~60° N, focusing on deep basins and shelf seas in the high Arctic Ocean, the Nordic seas, Baffin Bay, Hudson Bay and the Canadian Arctic Archipelago, derived from climatological ocean data. In the high Arctic Ocean, the first Rossby radius increases from ~5 km in the Nansen Basin to ~15 km in the central Canadian Basin. In the shelf seas and elsewhere, values are low (1–7 km), reflecting weak density stratification, shallow water, or both. Seasonality strongly impacts the Rossby radius only in shallow seas, where winter homogenization of the water column can reduce it to below 1 km. Greater detail is seen in the output from an ice–ocean general circulation model, of higher resolution than the climatology. To assess the impact of secular variability, 10 years (2003–2012) of hydrographic stations along 150° W in the Beaufort Gyre are also analysed. The first-mode Rossby radius increases over this period by ~20%. Finally, we review the observed scales of Arctic Ocean eddies.

Short summary
Knowledge of the size of the Rossby radius is important, because it is the horizontal scale of boundary currents, eddies and fronts in fluids on a rotating planet. We find that, in the deep basins of the Arctic Ocean, the Rossby radius is around 10km, but in the shallow shelf seas, it can be less than 1km. This presents a challenge to measurements and models alike.