Southern Ocean sea ice concentration budgets of five ocean-sea ice reanalyses

Abstract In this study, sea ice concentration (SIC) budgets were calculated for five ocean-sea reanalyses (CFSR, C-GLORSv7, GLORYS12v1, NEMO-EnKF and ORAS5), in the Southern Ocean compared with observations. Benefiting from assimilation of SIC, reanalysis products display a realistic representation extent as well area. However, when applying SIC budget diagnostics to decompose changes into contributions advection, divergence, thermodynamics, deformation data assimilation, we find that both atmospheric oceanic forcings model configurations are significant contributors on differences. For CFSR, primary source deviation other is stronger northward component velocity, which results advection divergence. Anomalous surface currents CFSR proposed be main cause velocity anomaly. Furthermore, twice mean thickness makes it more susceptible wind stresses under Coriolis forces, exacerbating drift ice. The GLORYS12v1 have some underestimation contribution divergence autumn, winter spring observations, but reasonable summer. ORAS5, although using same coupled forcing C-GLORSv7 has these two reanalyses. suggest future should focus improving modelling velocities, example through