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) exerts substantial influences on variabilities in the atmospheric circulation and Antarctic climate. In this study, it is revealed that the intensity of SPCZ can change the Amundsen Sea sea ice during the austral autumn, which is significantly independent of the El Niño-Southern Oscillation (ENSO). Observational and numerical results suggest that the stronger-than-usual SPCZ can generate a poleward-propagating Rossby wave train along a great circle route and induce a reduced Amundsen Sea Low (ASL) near West Antarctica, which may somewhat offset the teleconnections exerted by ENSO. These noticeable changes in the strength and zonal extent of ASL robustly lead to a tripole response of sea-ice perturbations in the Ross, Amundsen, and Weddell Seas. We find that the wind-driven dynamical process determines the local sea-ice changes, while the thermodynamical process is trivial. This research underscores the need to consider the SPCZ variability for a comprehensive understanding of sea-ice changes in West Antarctica on the interannual time scale.