Decadal Sea Ice Prediction in the West Antarctic Seas with Ocean and Sea Ice Initializations

Antarctic sea ice plays an important role in the formation of Antarctic Bottom Water that travels over global oceans and affects global climate. Here we demonstrate that decadal sea ice variability in the west Antarctic seas can be predicted with significant skills using a coupled general circulation model. We present three decadal reforecast experiments where only sea surface temperature, sea surface temperature and sea ice concentration, or sea surface temperature, sea ice concentration and subsurface ocean temperature and salinity are initialized with observations. We find that initializing all three components leads to the highest prediction skills of the sea ice concentration in the Amundsen-Bellingshausen Sea. This experiment captures decadal sea ice increase after the late 2000s, which is linked to anomalous sea ice advection from the Ross Sea and anomalous subsurface ocean cooling by the strengthened Antarctic Circumpolar Current. Skillful prediction of decadal sea ice variability benefits from combined ocean and sea ice initializations.