The Southern Ocean Response to Momentum and Buoyancy Forcing Anomalies

We present results on the sensitivity of Southern Ocean dynamics and heat uptake to changes in surface forcing. We use an ocean-sea ice model (OGCM) at two different horizontal resolution and force it with selected forcing anomalies. The anomalous forcing applied is the Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) surface flux perturbations (Gregory et al, 2016). FAFMIP anomalies are the results of CMIP5 atmosphere-ocean general circulation models (AOGCM) under the scenario called 1pctCO2. We first obtained a suite of OGCM simulations that are qualitatively and quantitatively in agreement with AOGCMs under the FAFMIP protocol. Then, we investigated the relative role of each individual surface forcing anomalies (momentum, buoyancy, heat and freshwater) on the dynamics and sensitivity of the Antarctic Circumpolar Current, upper and lower Meridional Overturning Circulation and changes in ocean heat content. The analysis presented helps in understanding the control exerted on Southern Ocean dynamics by momentum and buoyancy changes.