资源环境科技发展态势分析平台

Unlike the rapid decline of Arctic sea ice in the warming climate, Antarctic sea-ice extent exhibits a modest positive trend in the period of near four decades. In recent years, the fluctuation in Antarctic sea ice has been strengthened, including a decrease toward the lowest sea-ice extent in February 2011 for the period of 1978-2016 and a strong rebound in the summer of 2012. The sea-ice recovery mainly occurs in the Weddell Sea, Bellingshausen Sea, Amundsen Sea, southern Ross Sea, and the eastern Somov Sea. This study offers a new mechanism for this summertime sea-ice rebound. We demonstrate that cloud-fraction anomalies in winter 2011 contributed to the positive Antarctic sea-ice anomaly in summer 2012. The results show that the negative cloud-fraction anomalies in winter 2011 related to the large-scale atmospheric circulation resulted in a substantial negative surface-radiation budget, which cooled the surface and promoted more sea-ice growth. The sea-ice growth anomalies due to the negative cloud forcing propagated by sea-ice motion vectors from September 2011 to January 2012. The distribution of the sea-ice anomalies corresponded well with the sea-ice concentration anomalies in February 2012 in the Weddell Sea and eastern Somov Sea. Thus, negative cloud-fraction anomalies in winter can play a vital role in the following summer sea-ice distribution.