Impact of model resolution on North Atlantic heat transport and Arctic sea ice

Doroteaciro Iovino1, David Docquier2, Jeremy P Grist3, Malcolm J Roberts4, Christopher Roberts5, Tido Semmler6, Leandro Ponsoni2, Francois E Massonnet7, Dmitry Sidorenko8, Dmitry Sein6, Alessio Bellucci9 and Thierry Fichefet7, (1)Euro-Mediterranean Center on Climate Change, Ocean Modeling and Data Assimilation Division, Bologna, Italy, (2)UCLouvain, Louvain-la-Neuve, Belgium, (3)National Oceanography Centre, Southampton, United Kingdom, (4)Met Office Hadley center for Climate Change, Exeter, United Kingdom, (5)ECMWF, Reading, United Kingdom, (6)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany, (7)Université Catholique de Louvain, Georges Lemaître Centre for Earth and Climate Research, Earth and Life Institute, Louvain-La-Neuve, Belgium, (8)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research, Bremerhaven, Germany, (9)Euro-Mediterranean Center on Climate Change, Climate Simulations and Predictions Division, Bologna, Italy
Arctic sea-ice area and volume have substantially decreased since the beginning of the satellite era. The enhanced oceanic heat transport (OHT) from the North Atlantic into the Arctic Ocean has contributed to the sea ice loss.

Increasing the horizontal resolution of general circulation models (GCMs) improves their ability in representing the complex interplay of processes at high latitudes. The impact of model resolution on Arctic sea ice and Atlantic OHT is investigated by using five different state-of-the-art coupled GCMs (and 12 model configurations), which include dynamic representations of the ocean, atmosphere and sea ice. The models participate in the High Resolution Model Intercomparison Project (HighResMIP) of the Coupled Model Intercomparison Project Phase 6 (CMIP6).

Model results covering the 1950–2014 period, are compared to a suite of observational datasets. In the models studied, a finer ocean resolution drives lower Arctic sea-ice area and volume, generally enhances Atlantic OHT, and largely improves the representation of ocean surface characteristics, such as sea-surface temperature (SST) and velocity fields.

The model results highlight a clear anticorrelation at interannual time scales between Arctic sea ice (area and volume) and Atlantic OHT north of 60N. However, the strength of this relationship is not systematically impacted by model resolution. The higher the latitude used to compute OHT, the stronger the relationship between sea-ice area/volume and OHT. In Barents/Kara Sea and Greenland–Iceland–Norwegian Seas, the sea ice is more strongly connected to the Atlantic OHT compared to other Arctic regions.