Roles of Arctic sea ice and the preceding summer Arctic atmospheric circulation anomalies in the at-mospheric circulations anomalies of 2011/2012 and 2015/2016 winters
Using the NCEP/NCAR re-analysis data (re-analysis I),the ERA-Interim re-analysis data,and Hadley Center Arc-tic sea ice concentration data,main characteristics of atmospheric circulation anomalies in the winters of 2011/2012 and 2015/2016 were investigated based on diagnostic analysis and numerical simulations,and the possible causes were revealed.The re-sults indicate that although sea surface temperature anomalies in the tropical Pacific in the two winters corresponded to a weak La Ni~na and a strong El Ni~no event respectively and were distinctly different,the Siberian high was very strong in both win-ters,ranking the highest and the 5th highest since 1979,respectively.Autumn Arctic sea ice loss is a major reason that causes strong Siberian high in both winters.More important,anticyclonic surface winds in the preceding summer season over the Arc-tic Ocean and higher than normal air temperatures in the mid-and low-troposphere aloft strengthen the negative feedback of Arctic sea ice loss on the winter atmospheric variability,which further enhances the Siberian high and thereby favors the occur-rence of extreme cold events in East Asia.Apparently the dynamic and thermal dynamic conditions of summer Arctic atmos-pheric circulation not only influence Arctic sea ice in the summer and autumn,but also modulate the effects of Arctic sea ice loss on winter atmospheric variability.The strong El Ni~no event in the winter of 2015/2016 couldn't offset effects of Arctic sea ice loss and atmospheric circulation anomalies on the winter atmospheric variability over East Asia.
国家科技期刊平台
NSTL
万方数据
维普
