摘要
近几十年来,在全球变暖背景下,北极海冰不断减少,但南极海冰却在小幅增加。正当人们试图解释南极海冰这一"变暖悖论"时,2016年末南极海冰范围却突然跌破纪录,达到历史最低。其中,12月海冰减少范围最大,达到2.13×10^(6)km^(2),相对于1981–2010年的30年平均海冰范围减少了20.5%。这立即引起了科学界的极大关注,人们从大气环流、物理海洋和冰间湖等诸多方面,对其成因进行了大量研究,本文对这些工作进行了归纳总结。结果显示:在大气方面,主要的异常信号包括9–10月的纬向3波异常和11–12月的负位相南半球环状模以及气旋活动增加等,纬向3波大气环流受到热带太平洋和印度洋海温异常的调制,而南半球环状模异常主要是平流层极涡减弱下传导致;海洋方面,南大洋海温较常年偏暖,威德尔海出现了自1976年以来最大的冰间湖,对海冰减少起着不可忽视的作用。然而,当前的研究难以说明这一极端事件是由全球变暖或其他外部强迫主导,还是由气候系统内部变率产生,亦或者是两者的共同作用。对这些问题的回答直接关系到未来南极海冰趋势的预估,是亟待解决的科学问题和潜在的研究热点。
Along with the global warming,the sea ice in the Arctic decreased rapidly,however the sea ice in the Antarctic has experienced a weak expansion.While many researchers are studying the mechanisms for this paradox in the Antarctic,the sea ice extent(SIE)began a rapid decline in 2016 and reached a record low in austral spring2016.A rapid decrease of SIE anomaly occurred in December,with a 20.5%(2.13×10^(6)km^(2))reduction compared with the long-term(1981-2010)mean(10.41×10^(6)km^(2)).It attracted a lot of attentions and scientists have investigated the causes of its occurrence from various aspects,such as the atmosphere circulations,the thermal state of the ocean,the polynya and so on.Their main results are summarized in this review.On the atmospheric aspect,the general circulation signals include a zonal height anomalies chain with wave number three during September and October,a Southern Annular Mode anomaly during November and December,and intensified cyclonic activity.The atmospheric zonal wave number three is modulated by the sea surface temperature anomalies in the tropical Pacific and Indian Ocean,and the Southern Annular Mode anomaly is mainly a result of downward weakening stratospheric polar vortex.On the ocean aspect,the upper ocean temperature is warmer than normal,and there is a large polynya in the Weddell Sea,which has the greatest area in the period of 1976-2016.However,it is difficult to identify the relative contributions of the external forcings of the climate system,the internal variability of the climate system,or their collaborative roles.We hope the summary can be useful to improve the understanding of the changes of Antarctic sea ice and its origins.
作者
李双林
韩哲
刘娜
张超
蔡慧
Li Shuanglin;Han Zhe;Liu Na;Zhang Chao;Cai Hui(Department of Atmospheric Science,China University of Geosciences,Wuhan 430074,China;Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China)
出处
《海洋学报》
CAS
CSCD
北大核心
2021年第7期1-10,共10页
基金
中国科学院战略性先导专项“地球大数据科学工程”项目七之子任务“南极气候变化及其对东亚夏季气候的影响”(XDA19070402)。
