秋季北极海冰与欧亚冬季气温在年代际和年际尺度上的不同联系  

Decadal/interannual linking between autumn Arctic sea ice and following winter Eurasian air temperature

作　　者：何金海[1] 武丰民[1] 祁莉[1] 

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,南京210044

出　　处：《地球物理学报》2015年第4期1089-1102,共14页Chinese Journal of Geophysics

基　　金：国家重点基础研究发展计划(973计划)(2013CB430202);国家自然科学基金项目(41475086);长江学者和创新团队发展计划(PCSIRT);江苏高校优势学科建设工程项目(PAPD);江苏省青蓝工程创新团队项目资助

摘　　要：北极海冰的急剧消融在近年来欧亚大陆频发的低温事件中扮演着关键角色.秋季北极海冰的偏少对应着冬季欧亚大陆的低温天气,然而二者的联系在年代际和年际两种时间尺度上存在显著区别.本文运用1979—2012年哈德莱中心第一套海冰覆盖率(HadISST1)、欧洲中心(ERA_Interim)的2m温度、风场、海平面气压场、高度场等资料,分别研究了年代际和年际时间尺度上前期秋季北极海冰与欧亚冬季气温的联系.结果表明,欧亚和北极地区(0°—160°E,15°N—90°N)的冬季气温具有显著的年代际和年际变化.在年代际尺度上,温度异常分布在21世纪初由北极冷-大陆暖转为北极暖-大陆冷.这一年代际转折与前期秋季整个北极地区的海冰年代际减少联系密切.秋季北极全区海冰年代际偏少对应冬季欧亚大陆中高纬地区的高压异常,有利于北大西洋的暖湿气流北上和北极的冷空气南侵,造成北极暖-大陆冷的温度分布;在年际时间尺度上,温度异常分布主要由第一模态的年际变化部分和第二模态组成,且第一模态包含的年际变率信号也存在显著的年代际变化.年际尺度上全区北极海冰对欧亚冬季气温的影响远不及位于北冰洋西南边缘的巴伦支海、喀拉海和拉普捷夫海西部(30°E—120°E,75°N—85°N)的关键区海冰影响显著.关键区内海冰的偏少会引发冬季的北大西洋涛动负位相,导致北大西洋吹往欧亚大陆的暖湿气流减弱和欧亚大陆中高纬地区的气温偏低.The rapid reduction of Arctic sea ice plays a critical role in the recent cold winter extremes over Eurasian continent. Although the autumn Arctic sea ice with low concentration is related to anomalously cold Eurasian winters, the linking between them are significantly different on the decadal and interannual timescales. The winter surface air temperature （SAT） from 1979 to 2012 over Eurasia and Arctic （EAA） is investigated. Its decadal and interannual timescalessignals were extracted to study their relationships with the Arctic sea ice. The atmospheric circulation is also analyzed to study the potential mechanism. This study is based on Hadley Centre% sea ice dataset （HADISST1） and European Center for Medium-Range Weather Forecast （ECMWF） Re-Analysis （ERA-Interim） atmospheric data from 1979 through 2012. We utilize empirical orthogonal function （EOF） analysis （based on the correlation matrix） to extract the leading modes of the winter 2-m temperature over EAA （0°-160°E,15°N--90°N）. The decadal and interannual variations for winter SAT are separated by Gussian filtration as well as other statistic methods like the linear regression and the wavelet analysis. We have these results. （1） The winter SAT of EAA has remarkabe interannual and decadal variations. On the decadal timescale, the leading pattern changed from cold-Arctic and warm- Eurasia to warm-Arctic and cold-Eurasia. The interannual variation mainly includes the interannual signal in the first and second modes. The dominant interannual cycle in the first mode is shortened from 4~7 years to 2~4 years since 2004. （2） The decadal shift is closely related to the reduction of sea ice over the whole Arctic. A strong anticyclonic anomaly was generated over the mid- and high-latitude Eurasian continent together with the decadal decreasing of the whole Arctic sea ice. It favorably drove northward warm moist flow from North Atlantic into Arctic as well as southward cold flow from Arctic into mid- and high-latitude of Eura

关 键 词：秋季北极海冰 冬季欧亚低温 年代际 年际 

分 类 号：P731[天文地球—海洋科学] P461