Eddying Arctic Ocean

Project Rationale
Continuous sea ice retreat impacts mesoscale/sub-mesoscale ocean dynamics in the Arctic Ocean, mixing and ventilation, bio-geochemistry and ocean carbon uptake. Evolution of the Arctic eddy field in the future will have important consequences for atmosphere-ocean interactions, affecting regional and global climate. Observations show a decrease in eddy horizontal size in the less compact ice – Marginal Ice Zone (MIZ) [1], which suggest changes in the eddy energy field, in freshwater and heat transports in the future Arctic as sea ice declines [2]. The relationship between the horizontal size of eddies and the depth they can penetrate is not known. “Tall” eddies can extend from the halocline up to ~3000 m, providing ventilation of the deep ocean [3]. With recent advances in modelling and satellite techniques it is now possible to make a detailed assessment of eddy statistics in the open ocean and under sea ice to examine changes in eddy dynamics. The project will address the impact of sea ice decline on eddies, and on the emerging mechanisms and feedbacks which can affect ocean stratification and ventilation and further accelerate sea ice decline. This will inform development of the next generation of the high-resolution climate models.

Methodology
The project will focus on the analysis of the output from a state-of-the-art high-resolution ocean-sea ice model NEMO-1/12 degree (1) coupled to the high-resolution UK Metoffice atmospheric model and (2) forced with atmospheric reanalysis. The model simulations will be analysed to generate eddy statistics for open ocean and MIZ regions in the Arctic. Comparison will be made with satellite observations for surface eddies and with the mooring data for halocline and deep eddies in different Arctic regions. The links established in the FAMOS project between the NOC and the Woods Hole Oceanographic Institution (Prof Proshutinsky), Yale University (Prof Timmermans) and Dr Kozlov (Satellite Oceanography Laboratory, Russian State Hydrometeorological University) will assist with this task. The model simulations will be used to calculate eddy transports and relate these to multi-decadal changes in heat and freshwater content in the Arctic. Eddy generation “hotspots” at the steep topography along the continental Arctic shelf and mid-oceanic ridges and eddy dissipation in the ocean interior along with effect of sea ice-ocean coupling on eddy energy will be examined. Finally, assessment of the existing sub-grid scale eddy parameterisations will be conducted, based on the high-resolution model results and data to inform coarse resolution climate models.

Training
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the National Oceanography Centre Southampton. Specific training will Include access to a range of high-level courses taught at the University of Southampton, training in state-of-the-art ocean modelling and analysis of the high-resolution model output. The student will join the UK’s most active large-scale ocean modelling group and through a variety of ongoing national and international projects at NOC will have opportunities to participate in marine research at sea and became engaged with the international community of Arctic researchers. This will help develop strong communication and team-working skills and equip the student for future employment in the fields of Oceanography and Climate Modelling.