东西伯利亚——波弗特海海冰多年代际变率及其与大西洋多年代际振荡的联系  

Multidecadal variability of sea ice in the East Siberia——Beaufort Sea region and its linkage with the Atlantic Multidecadal Oscillation

作　　者：刘莉 张文君[1] 刘超[1] LIU Li;ZHANG Wenjun;LIU Chao(Key Laboratory of Meteorological Disaster of Ministry of Education,Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing 210044,China)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心,南京210044

出　　处：《气象学报》2023年第1期137-151,共15页Acta Meteorologica Sinica

基　　金：国家自然科学基金项目(42088101、42125501)。

摘　　要：基于哈得来中心(Hadley Centre)逐月的海表温度、海冰密集度资料以及美国国家环境预报中心/国家大气研究中心(NCEP/NCAR)的大气环流再分析资料,分析了1950—2020年秋季(8—10月)东西伯利亚—波弗特海(East Siberian-Beaufort,EsCB)海冰年代际变化的时空特征,并阐述了大西洋多年代际振荡(Atlantic Multidecadal Oscillation,AMO)对EsCB海冰年代际变率的可能调制作用。结果表明,EsCB是秋季北极海冰年代际变化最主要的区域,该区海冰密集度年代际变率可占其异常总方差的40%以上。进一步研究发现,AMO对秋季EsCB海冰存在明显的调制作用,在AMO正位相,北大西洋正海温异常激发向极传播的大气罗斯贝波列,有利于北极中部出现高压异常,相应的大气绝热下沉运动使得对流层低层出现明显的升温,从而有利于EsCB海冰的融化。与此同时,地表升温和EsCB海冰消融会引起局地云量的增多、大气向下长波辐射增大,这反过来又使得地表气温升高,这种地表气温-云-长波辐射的正反馈过程有利于年代际海冰信号的长时间维持。耦合模式的北大西洋“起搏器”试验可以很好地再现观测中AMO调制EsCB秋季海冰的物理过程,进一步佐证了本研究的结论。This work investigates the spatial and temporal features of boreal autumn(August—October)East Siberian—Beaufort(EsCB)sea ice on decadal timescales during the period of 1950—2020 based on monthly Sea Surface Temperature(SST),Sea Ice Concentration(SIC)from the Hadley Center and atmospheric reanalysis dataset provided by the National Centers for Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR).The possible modulation effects of Atlantic Multidecadal Oscillation(AMO)on the EsCB sea ice are further elaborated.The EsCB sea displays the strongest decadal component of sea ice in the Arctic,accounting for more than 40%of the local total variance of SIC anomalies.Our further analyses show that the AMO exerts a prominent modulation on the EsCB sea ice.In the positive AMO phase,warm North Atlantic SST anomalies trigger poleward propagating atmospheric Rossby waves,favoring the establishment of an anomalous high over the central Arctic region.The corresponding adiabatic descending motion warms the lower troposphere and causes the EsCB sea ice to melt.The surface warming and EsCB sea ice melting can simultaneously give rise to an increase in local cloud amount and downward longwave radiation,which in turn increases the surface air temperature.This surface air temperature-cloud-longwave positive feedback is beneficial for the long-term maintenance of the decadal sea ice signal.The North Atlantic pacemaker experiments can realistically reproduce the observed physical process as shown above,which further supports our main conclusions.

关 键 词：北极海冰 东西伯利亚—波弗特海 大西洋多年代际振荡 年代际调制 

分 类 号：P46[天文地球—大气科学及气象学]