Seminar: Dr. Carolina Dufour

Please join us as we welcome Dr. Carolina Dufour from the department of Atmospheric and Oceanic Sciences at Princeton University for her seminar titled "On the role of the ocean mesoscale in the meridional circulation of the Southern Ocean".Refreshments will be served.

Abstract

The Southern Ocean plays a crucial role in the climate system by taking up and redis-tributing heat and carbon at the global scale. Because the Southern Ocean is one of the most under-sampled regions of the global ocean, questions still remain regarding the merid-ional circulation and its response to climate change. One important player in the Southern Ocean circulation is the transport eff?ected by transient mesoscale eddies. These eddies, which are ubiquitous features of the order of 10 to 100 km, oppose the wind-driven circulation and transport physical and biogeochemical tracers. However, due to their relatively small size and high-temporal variability, transient mesoscale eddies are challenging to observe and model.

In this seminar, we will investigate the role of transient mesoscale eddies in the Southern Ocean meridional circulation using ocean models at eddying resolution. We will ?first examine how the transport e?ffected by transient mesoscale eddies contributes to reduce the intensi?-fication of the meridional overturning circulation driven by increasing westerly winds. We will then explore the role played by transient mesoscale eddies in transporting heat and biogeo-chemical tracers across the intense fronts of the Southern Ocean. While in both cases transient mesoscale eddies are found to play an important role in compensating the wind-driven circulation and transporting tracers, another important player, stationary meanders, emerges from our analyses. Stationary meanders are particularly vigorous in the Southern Ocean due to the intense Antarctic Circumpolar Current intersecting with numerous major topographic obstacles along its path around Antarctica. Our results highlight the complementarity of stationary meanders and transient eddies in the compensation of the wind-driven circulation and transport of climate-relevant tracers. Moreover, the importance of stationary meanders, or in other words, the importance of the inter- and intra-basin variability of the circulation, provides a new picture of the Southern Ocean circulation that departs from the traditional two-dimensional zonally-averaged view.