1.School of Atmospheric Sciences,Chengdu University of Information Technology;2.The Institute of Atmospheric Physics,Chinese Academy of Sciences
Strategic Project of Chinese Academy of Science (Grant XDA19070402)
Based on the sea ice data from 1979 to 2017, this work used linear regression and a linear baroclinic model to investigate the differences of Antarctic sea ice during two types of El Ni?o events (EP and CP) and its possible physical mechanisms. The results suggest that the amplitude and the spatial pattern of sea ice anomalies are different, although there are some similarities. The sea ice anomalies in the Ross Sea and Amundsen Sea in EP and CP event are negative, but they are stronger in the EP event than CP event. The sea ice anomalies in the Weddell Sea are positive, and they are stronger and northwestward in the EP event relative to the CP event. The difference of sea temperature anomalies intensity between EP and CP events is an important reason for the different amplitude of sea ice. The sea surface temperature anomalies are stronger in the EP event than the CP event, and force a Pacific-South America teleconnection pattern with a stronger high-pressure anomaly. Such atmospheric circulation leads to northeast wind anomaly in Ross Sea in the EP event, which transport sea ice to high latitudes and the sea ice decreases, and causes south wind anomaly in Weddell Sea, which accumulate sea ice on the northern Weddell Sea. Compared to the EP event, the Pacific-South America teleconnection anomaly forced by the CP event is weaker, which induced weaker sea ice anomalies. In fact, the positive anomaly of sea ice in Weddell Sea has appeared in previous November during the CP event, and strengthened due to the ice-albedo feedback in the following spring. Our results suggest that sea ice anomalies are stronger when the sea surface temperature anomalies in the tropical Pacific are stronger. It is different from that indicated in previous studies, but is more reasonable.