Both the Southern Annular Mode (SAM) and the El Niño Southern Oscillation (ENSO) are two critical factors contributing to the Antarctic sea ice variability, with strong correlation with each other. The impacts of combined ENSO and SAM on the Antarctic seasonal sea ice anomalies budget are assessed in this study by investigating sea ice concentration (SIC) observations and atmospheric reanalysis data. Based on the monthly ENSO–SAM standardized indices four special situations are selected, including LN/SAM+, LN/SAM-, EN/SAM+, and EN/SAM-. In phase events (LN/SAM+ & EN/SAM–) are characterized with distinct sea level pressure anomalies in the Amundsen Sea and a 850-hPa temperature dipole over the West Antarctic coastal oceans, while out of phase events (EN/SAM+ & LN/SAM–) with only pressure anomalies over the whole Antarctic and few temperature anomalies. All the four situations contribute to the similar spatial patterns of sea ice concentration anomalies with seasonal variations, presenting a dipole over the Atlantic and Pacific sectors. Sea ice dynamic and thermodynamic budget analyses are conducted to determine the leading processes involving the sea ice anomalies. The results show that thermodynamic processes dominate in summer and spring, due to the increased short-wave radiation fluxes and the ice-albedo feedback. Dynamic processes have larger contributions in autumn and winter than other seasons, with advection causes sea ice anomalies at the ice edge and divergence works in the inner ice pack. Meanwhile, sensible and latent heat fluxes result in the thermodynamically sea ice anomalies.
Both the Southern Annular Mode (SAM) and the El Niño Southern Oscillation (ENSO) are two critical factors contributing to the Antarctic sea ice variability, with strong correlation with each other. The impacts of combined ENSO and SAM on the Antarctic seasonal sea ice anomalies budget are assessed in this study by investigating sea ice concentration (SIC) observations and atmospheric reanalysis data. Based on the monthly ENSO–SAM standardized indices four special situations are selected, including LN/SAM+, LN/SAM-, EN/SAM+, and EN/SAM-. In phase events (LN/SAM+ & EN/SAM–) are characterized with distinct sea level pressure anomalies in the Amundsen Sea and a 850-hPa temperature dipole over the West Antarctic coastal oceans, while out of phase events (EN/SAM+ & LN/SAM–) with only pressure anomalies over the whole Antarctic and few temperature anomalies. All the four situations contribute to the similar spatial patterns of sea ice concentration anomalies with seasonal variations, presenting a dipole over the Atlantic and Pacific sectors. Sea ice dynamic and thermodynamic budget analyses are conducted to determine the leading processes involving the sea ice anomalies. The results show that thermodynamic processes dominate in summer and spring, due to the increased short-wave radiation fluxes and the ice-albedo feedback. Dynamic processes have larger contributions in autumn and winter than other seasons, with advection causes sea ice anomalies at the ice edge and divergence works in the inner ice pack. Meanwhile, sensible and latent heat fluxes result in the thermodynamically sea ice anomalies.

Antarctic,Sea ice,Thermodynmic,Dynamic