South Pacific Convergence Zone Impacts on the Autumn Sea Ice Changes in West Antarctica

As one of the strongest convection bands in the Southern Hemisphere, the South Pacific Convergence Zone (SPCZ) substantially influences the variabilities in the atmospheric circulation and Antarctic climate. In this study, it is revealed that the intensity of the SPCZ can change the characteristics of sea ice in the West Antarctica during austral autumn, which is significantly independent of the El Niño-Southern Oscillation (ENSO). Observational and numerical results suggest that a stronger-than-usual SPCZ can generate a poleward-propagating Rossby wave train along a great circular route and induce a weakening of the Amundsen Sea Low (ASL) near West Antarctica, which may somewhat offset the teleconnections exerted by ENSO. These changes in the strength and zonal extent of ASL is noticeable and robustly lead to a tripole response of sea-ice perturbations in the Ross, Amundsen, and Weddell Seas. We find that the wind-driven dynamical processes determine the local sea-ice changes, while the influence from thermodynamic processes is trivial. This research underscores the need to consider the SPCZ variability for a comprehensive understanding of sea-ice changes in West Antarctica on interannual timescales.