Global ocean and sea ice variability simulated in eddy-permitting climate models

Abstract. Ocean mesoscale eddies, which have a horizontal scale with an order of 100 km, play a prominent role in global ocean heat transport that regulates the Earth's climate. Most of climate models, however, cannot fully resolve the ocean mesoscale eddies because of the constraint of computational resources. To mitigate this shortcoming, we newly develop an eddy-permitting climate model, SINTEX-F3, which has the ocean resolution with the order of 25 km. Compared to other eddy-permitting climate models available from the CMIP6 HighResMIP, the SINTEX-F3 represents a cold bias in the mid-high latitudes and weaker El Niño-Southern Oscillation (ENSO). Despite the weaker ENSO, the SINTEX-F3 realistically reproduces other tropical climate phenomena such as the Indian Ocean Dipole and Atlantic Niño/Niña, indicating that these modes are less dependent on ENSO in the model. In the subtropical-midlatitudes, the SINTEX-F3 well captures mesoscale sea surface temperature and surface heat flux variability, particularly in the western and eastern boundary current regions. Furthermore, the SINTEX-F3 simulates the mean state and variability of sea ice in the Antarctic Sea more accurately than in the Arctic Sea, likely due to improvements in sea ice model physics and the increased ocean model resolution. While further efforts are needed to address the cold bias and the weaker ENSO representation, the SINTEX-F3 shows significant potential for simulating and predicting global ocean and sea ice variability at an eddy-permitting scale.