The E3SMv1-Arctic Ocean and Sea-Ice Regionally Refined Model
The Arctic Ocean is changing rapidly as the Arctic climate system warms at a much faster pace than the rest of the world. Modeling these changes is important for process understanding and predictability purposes, and yet challenging due to the complex interactions and feedbacks across different Earth system components that govern the dynamics of polar regions. This work describes the first E3SM Arctic-focused configuration for the ocean and sea ice model components, which allows for an improved representation of Arctic processes while continuing to explicitly represent teleconnections between the Arctic and the mid- and low-latitudes.
Compared to standard low-resolution E3SM results, the Arctic regionally refined configuration of E3SM improves the ocean circulation, temperature, and salinity through the Arctic gateways. Other larger-scale properties, such as the characteristics of Atlantic Water and the strength of the Atlantic Meridional Overturning Circulation (AMOC), are also improved. These improvements come at a fraction of the computational cost that is necessary to run an E3SM configuration with high horizontal resolution everywhere on the globe. The results represent a key step towards a full Arctic regionally refined configuration, including refinement in the atmosphere, land, and hydrology components.
E3SM is a state-of-the-science Earth system model with the ability to focus horizontal resolution of its multiple components in specific areas. Regional resolution refinement is motivated by the need to explicitly resolve, rather than parameterize, relevant physics within the regions of refined resolution, while offering significant computational cost savings relative to the respective cost of configurations with high resolution everywhere on the globe. This work is focused on the first Arctic regionally refined E3SM configuration for the ocean and sea-ice components (E3SM-Arctic), while employing data-based atmosphere, land, and hydrology components. We find that E3SM-Arctic increases the realism of simulated Arctic Ocean and sea-ice conditions compared to a similar standard low-resolution E3SM simulation. Exchanges through the main Arctic gateways are greatly improved, and other aspects, such as the Arctic freshwater content variability and sea-ice trends, are also satisfactorily simulated. Overall, E3SM-Arctic offers an improved representation of the Arctic system at a fraction (15%) of the computational cost of comparable global high-resolution configurations, while permitting exchanges with the lower-latitude oceans that cannot be directly accounted for in Arctic regional models.