Development of MITgcm ECCO-Downscaled Amundsen-Bellingshausen Sea Regional Simulation
Nakayama, Y., Hyogo, S., Lin, Y., Yat-sen, S., Park, T., Poinelli, M., Sathiyamohan, G., Zhang, H., and Dutrieux, P. (2026)
Presented at:
Ocean Sciences Meeting 2026Abstract
The Amundsen and Bellingshausen Seas (ABS) are among the most rapidly changing regions in the Southern Ocean, playing a critical role in Antarctic ice shelf mass loss and global sea-level rise. Several ocean models have been developed to understand these changes, revealing complex interactions between ocean circulation, sea ice, and ice shelf melt. However, differences in model configurations and parameter choices, along with the need for thorough evaluation, often limit their accessibility to the wider multidisciplinary community. Here, we present a high-resolution regional ocean model configuration based on the MITgcm, downscaled from the global ECCO LLC270 ocean state estimate and further optimized with regional observations. The model is rigorously evaluated against existing datasets, capturing key hydrographic features, sea-ice characteristics, and ice-shelf conditions, with a focus on mean state, as well as seasonal and interannual variability. Simulated temperature–salinity profiles and water-mass distributions closely match CTD and mooring observations. Sea-ice concentration and extent agree well with satellite data, including realistic representation of polynya formation and seasonal–spatial variability. Ice-shelf basal melt rates fall within observational ranges and reproduce spatial patterns consistent with known ocean access pathways beneath the shelves The configuration also incorporates passive tracers for surface water, ice-shelf meltwater, and Circumpolar Deep Water, as well as Lagrangian particle tracking, enabling studies of water-mass transformation and tracer pathways. We make the model code, configuration, evaluation diagnostics, passive-tracer outputs, and sensitivity simulations openly available, enabling the broader scientific community—including researchers beyond physical ocean modeling—to advance data interpretation, test hypotheses, and plan future observations in the ABS region.
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