Towards an improved Southern Ocean in the Earth System Model, CSIR VR-ESM

Abstract

The Southern Ocean is a key region for global carbon exchange, in which both physical and biological mechanisms drive carbon between the atmosphere and the surface ocean and ocean interior. Our research shows that the spatial scales of the surface ocean dynamics in the Southern Ocean are important in driving these exchanges, scales from mesoscale O (10-100km. down to submesoscale O (1km.. We consider the representation of these processes in our configuration of an Earth System Model (ESM.,the CSIR Variable Resolution Earth System Model (VR-ESM..ESMs consist of multiple individual, interacting numerical models each representing different system components such as the atmosphere, land and ocean, all simulating hundreds of years of earth/climate evolution. We thus have to balance out model complexity with available computational power (CPUs and wall time. which is provided by the CHPC, Centre for High Performance Computing. Mesoscale and submesoscale processes therefore can either be explicitly resolved by the model grid resolution or represented by a parametrization. Typically, the ocean component of ESMs run at mesoscale-permitting to mesoscale-resolving grid resolutions, resolving the submesoscale is still only possible for localised regional runs. We use the numerical model NEMO in a regional South Atlantic-Southern Ocean configuration as an experimental platform to inform ESM design choices for a better representation of the Southern Ocean. Through model sensitivity studies with NEMO’s ocean, ice and biogeochemistry components and understanding the surface ocean-biogeochemistry dynamics, the model solution is improved while also optimizing the model with consideration to computational power. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.