Modelling centrifugal instability presently relies upon idealised model configurations. For cases in which realistic simulations exist, models are often coarse resolution. CIOP moves beyond this by examining output in a realistic configuration for a long duration (2 years) at high spatial resolution (<100 m after the project). Furthermore, the resulting dataset facilitates testing of future parameterizations.
These results above move beyond the state of the art in another way: by addressing a fundamental question not previously answered. Despite numerous studies that have attempted to explain this question, we have demonstrated that, at low Richardson numbers, anticyclonic and cyclonic curved fronts are more and less stable, respectively. Perhaps more importantly, they undergo centrifugal/symmetric instabilities in a manner different than previously understood. The wider societal implications are two-fold. While this has certainly helped better understand vortex formation in the Orkney Passage (explained below), it may also have an impact for ocean-atmosphere exchange. For example, vertical motion will be enhanced in curved cyclonic meanders due to centrifugal/symmetric instabilities, while vertical motion will be suppressed within curved anticyclonic fronts. Because meandering fronts are ubiquitous in the world ocean, it may have implications for tracer exchange between the deep ocean and atmosphere (e.g. biology). The applicant has been in communication with fellow scientists about this topic, encouraging use of these ideas in their research.
Abyssal flows will preferentially generate anticyclonic vorticity owing to the manner in which the mean flow moves past topography: the flow exits canyons with steep topography on the left, regardless of hemisphere. This generates anticyclonic vortices. If such anticyclonic (stable) vortices trap fluid, this will act as a bolus transport of dense waters. In the Orkney Passage, this water is climatically important: it is Weddell Sea Deep Water (WSDW), some of which originates from shelf waters around Antarctica. However, such dense waters reside in other ocean basins with important implications for transport of water masses. Thus, the finding that intense anticyclones are weakly stable is a significant result of this MSCA-IF.
In summary, the wider societal implications of these results are that it will help to improve understanding and parameterizations of centrifugal instability within global climate models. This includes tracer exchange in the upper ocean, as well as bolus transport of watermasses.
