Fine-resolution ocean emulator for the Greenland-Scotland Ridge

Exchange of water masses across the Greenland-Scotland ridge is an important part of the AMOC. The complicated bathymetry of the ridge is not properly resolved in standard CMIP models with around 1 degree resolution and this reduces confidence in simulated exchanges and their variability. Previously, a nested-domain approach with finer resolution in selected areas has been applied. Here, we perform a pilot study of the alternative approach of a fine-resolution ocean emulator. We use daily 3D salinity and temperature fields of the GLORYS reanalysis in original (target) and 4x reduced (input) resolution and demonstrate that a fine-resolution emulator consisting of a simple U-net architecture trained on 10 years of  input/target can be used to reconstruct the target field from the input fields outside the training period with a significant skill compared to simple interpolation. We apply temporal and spatial scrambling to assess input feature importance. Our study suggests that the fine resolution model in a nested setup can be replaced with an ocean emulator leading to substantial gains in overall execution speed.