Regional sea surface height (SSH) changes due to an abrupt weakening of the Atlantic meridional overturning circulation (AMOC) are simulated with a high- and low-resolution model. A rapid decrease of the AMOC in the high-resolution version induces shorter return times of several specific regional and coastal extremes in North Atlantic SSH than in the low-resolution version. This effect is caused by a change in main eddy pathways associated with a change in separation latitude of the Gulf Stream.

We analyzed the ability of the ECCO2 reanalysis to represent the hydrographic properties and variability of Antarctic Bottom Water in the Southern Ocean. After 2004, the opening of an oceanic polynya in the Weddell Sea sector and consequent intense dense water production leads to an unrealistic scenario. Even before 2004, bottom waters are warmer and less dense than expected, while the absolute volume transport and velocity estimates are underrepresented.

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.

Measured vertical mixing profiles are applied to a 1-D phytoplankton model. Results show that shifts in vertical mixing are able to induce a transition from an upper chlorophyll maximum to a deep one and vice versa. Furthermore, a clear correlation between the surface phytoplankton concentration and mixing-induced nutrient flux is found for nutrient-limited cases. This result suggests that characteristics of the vertical mixing could be determined from the surface phytoplankton concentration.