北极海冰与全球气候变化

·编者按·

北极海冰与全球气候变化

·编者按·

根据NASA与NSIDC（美国国家冰雪数据中心）的研究数据显示，今年冬季北极海冰覆盖面积，为有卫星记录以来的最小值（图1）。2016年3月24日，冬季北极海冰达到年度最大值，覆盖面积为1452万km2，但这却是自1979年有卫星记录以来的最小值，这个数值比1981年至2010年冬季北极最大海冰覆盖面积的平均值缩减了111.6万km2。之前北极海冰有记录以来的最小覆盖面积，发生在2015年2月15日，冬季北极海冰达到年度最大值，覆盖面积为1454万km2，也就是说2016年冬季海冰的覆盖面积比2015年少了2万km2。总体上来说，冬季北极海冰的覆盖面积每10年大约下降2.8%，远小于夏季北极海冰的缩小面积，但都反映了北极长期变暖的趋势。

图1　北极海冰覆盖情况（美国国家雪冰中心统计）

北极海冰（arctic sea ice）是指北极地区直接由海水冻结而成的咸水冰，亦包括进入海洋中的大陆冰川、冰山和冰岛等。长期以来，北冰洋由密集的海冰所覆盖，夏季北冰洋海冰面积仅占冬季面积的10%左右。自20世纪70年代以来，全球气温持续升高，而北极的增暖趋势是全球平均的2倍以上。据科学家预测，在不久的将来，将会出现夏季无冰的北冰洋。北极海冰消融以及北极增暖不仅影响北极地区的生态环境，而且通过复杂的反馈过程对北半球天气气候产生影响。

已有的研究表明，在冬季，北极可以影响我国的天气和气候。我国北方冬季普遍增暖和极端严寒天气都与北极的作用密不可分。北极变化改变了大气环流，对沙尘和雾霾的输送强度产生重要影响。春季和秋季是冷暖气团彼此交锋和消长时期，通常与锋区的活动和北方的干旱过程相联系。北极的可能影响还有很多方面，如对海上风暴、夏季酷热、秋季降雪的影响等，其中大部分尚未充分研究。

北极对我国气候的影响会导致一系列重大的社会经济影响。比如对主要产粮区气候的影响，直接威胁到我国的粮食安全。又如气候灾害的发生，对全国产生多种可能的灾害。对北极变化的深入研究是推动北极变化对我国气候影响研究的主要渠道，攻克一系列尚未解决的科学问题，为解决北极影响我国的过程和机理、提高气候预测精度和水平奠定坚实的基础，支持国家有关部门提出切实的措施和必要的对策，应对北极变化对我国气候的强烈影响。

本专题得到秦大河院士（中国气象局）、赵进平教授（中国海洋大学）、沈永平研究员（《冰川冻土》编辑部）、武炳义副研究员（中国科学院大气物理研究所）的大力支持。

·热点数据排行·

截至2016年3月4日，中国知网（CNKI）和Web of Science（WOS）的数据报告显示，以“北极海冰（Arctic sea ice）”为词条可以检索到的期刊文献分别为201条与7688条，本专题将相关数据按照：研究机构发文数、作者发文数、期刊发文数、被引用频次进行排行，结果如下。

研究机构发文数量排名（CNKI）

研究机构发文数量排名（WOS）

作者发文数量排名（CNKI）

作者发文数量排名（WOS）

期刊发文数量排名（CNKI）

期刊发文数量排名（WOS）

根据中国知网（CNKI）数据报告，以“北极海冰（Arctic sea ice）”为词条可以检索到的高被引论文排行结果如下。

国内数据库高被引论文排行

（数据来源：中国知网，检索时间：2016-03-04）

根据Web of Science统计数据，以“北极海冰（Arctic sea ice）”为词条可以检索到的高被引论文排行结果如下。

国外数据库高被引论文排行

·经典文献推荐·

基于Web of Science检索结果，利用Histcite软件选取LCS（Local Citation Score，本地引用次数）TOP 50文献作为节点进行分析，得到本领域推荐的经典文献如下。

本领域经典文献

来源出版物：Journal of Geophysical Research Atmospheres, 1989, 94(C10): 14485-14498

Recent decrease of sea level pressure in the central Arctic

Walsh, JE; Chapman, WL; Shy, TL

Abstract: Arctic sea level pressure data from the period of the Arctic Ocean Buoy Program show a significant decrease in the annual mean. In every calendar month, the annual mean is lower in the second half of the 1979-1994 period than in the first. The changes of the annual means are larger in the central Arctic than anywhere else in the Northern Hemisphere. The decreases are largest and statistically significant in the autumn and winter. The annual anomalies became negative relative to the 16-yr mean in the 1980s and have been negative in every year since 1988. Correspondingly, the mean anticyclone in the Arctic pressure field has weakened and the vorticity of the gradient wind held over the central Arctic Ocean has became more positive than at any time in the past several decades. The pressure decrease, which has been compensated by pressure increases over the subpolar oceans, implies that the wind forcing of sea ice contains an enhanced cyclonic component relative to earlier decades.

来源出版物：Journal of Climate, 1996, 9(2): 480-486

Thinning of the Arctic sea-ice cover

Rothrock, DA; Yu, Y; Maykut, GA; et al.

Abstract: Comparison of sea-ice draft data acquired on submarine cruises between 1993 and 1997 with similar data acquired between 1958 and 1976 indicates that the mean ice draft at the end of the melt season has decreasedby about 1.3 m in most of the deep water portion of the Arctic Ocean, from 3.1 m in 1958-1976 to 1.8 m in the 1990s. The decrease is greater in the central and eastern Arctic than in the Beaufort and Chukchi seas. Preliminary evidence is that the ice cover has continued to become thinner in some regions during the 1990s.

来源出版物：Geophysical Research Letters, 1999, 26(23): 3469-3472

Arctic sea ice extents, areas, and trends, 1978-1996

Parkinson, CL; Cavalieri, DJ; Gloersen, P; et al.

Abstract: Satellite passive-microwave data for November 1978 through December 1996 reveal marked seasonal, regional, and interannual variabilities, with an overall decreasing trend of −34300±3700 km2/yr(−2.8%/decade) in Arctic sea ice extents over the 18.2-year period. Decreases occur in all seasons and on a yearly average basis, although they are largest in spring and smallest in autumn. Regionally, the Kara and Barents Seas have the largest decreases, at −15200±1900 km2/yr(−10.5%/decade), followed by the Seas of Okhotsk and Japan, the Arctic Ocean, Greenland Sea, Hudson Bay, and Canadian Archipelago. The yearly average trends for the total, the Kara and Barents Seas, and the Seas of Okhotsk and Japan all have high statistical significance, with the null hypothesis of a 0 slope being rejected at a 99% confidence level. Regions showing increasing yearly average ice extents are Baffin Bay/Labrador Sea, the Gulf of St. Lawrence, and the Bering Sea, with only the increases in the Gulf of St. Lawrence being statistically significant at the 99% level. Hemispheric results for sea ice areas exhibit the same −2.8%/decade decrease as for ice extents and hence a lower absolute decrease(−29500±3800 km2/yr), with the ice-free area within the ice pack correspondingly decreasing at −4800±1600 km2/yr. Confidence levels for the trends in ice areas and ice-free water areas exceed 99% and 95%, respectively. Nonetheless, interannual variability is high, and, for instance, the Arctic Ocean ice extents have a positive trend 1990–1996, in spite of their negative trend for the time period as a whole.

来源出版物：Journal of Geophysical Research Oceans, 1999, 104(C9): 20837-20856

The Arctic’s rapidly shrinking sea ice cover: A research synthesis

Stroeve, Julienne C; Serreze, Mark C; Holland, Marika M; et al.

Abstract: The sequence of extreme September sea ice extent minima over the past decade suggests acceleration in the response of the Arctic sea ice cover to external forcing, hastening the ongoing transition towards a seasonally open Arctic Ocean. This reflects several mutually supporting processes. Because of the extensive open water in recent Septembers, ice cover in the following spring is increasingly dominated by thin, first-year ice(ice formed during the previous autumn and winter) that is vulnerable to melting out in summer. Thinner ice in spring in turn fosters a stronger summer ice-albedo feedback through earlier formation of open water areas. A thin ice cover is also more vulnerable to strong summer retreat under anomalous atmospheric forcing. Finally, general warming of the Arctic has reduced the likelihood of cold years that could bring about temporary recovery of the ice cover. Events leading to the September ice extent minima of recent years exemplify these processes.

来源出版物：Climatic Change, 2012, 110(3-4): 1005-1027

·推荐综述·

北极海冰减退引起的北极放大机理与全球气候效应

赵进平，史久新，王召民，李志军，黄菲

北极是地球的寒极，是北半球气候系统稳定的重要基础之一。长期以来，北冰洋由密集的海冰覆盖，夏季北冰洋海冰融化面积仅占冬季的10%左右。自从20世纪70年代以来，全球气温持续升高，全球变暖已经成为不争的事实。全球变暖对北极产生了持续的影响，导致北极逐渐变暖。21世纪以来，北极增暖的趋势是全球平均水平的2倍，被称为“北极放大”现象。

北极放大的原因之一是其下垫面主要是海洋。夏季海冰厚度和覆盖面积的减小直接导致海洋吸收太阳辐射能的增加，一方面加剧海冰的融化，一方面越来越多的开阔海面对大气产生异常加热，形成正反馈效应。在各种可能的反馈中，最为明确的正反馈是海冰—气温反馈（即冰雪反照率反馈）。这种加快的正反馈过程不仅会影响极区的气候变化，而且还会加剧北极对高纬气候的放大效应。由于更加温暖的寒极改变了地球热机的行为，对全球气候产生非常显著的影响。海冰和海洋的变化过程将会导致北极气候变化到达临界点（tipping point），产生强烈的全球效应。

本文根据国内外最新研究成果，归纳关于北极海冰减退引起的北极放大机理与全球气候效应有关的主要科学问题，从更广阔的视野看待北极的变化，指出需要重点开展的研究工作，促进多学科的交叉，推动北极科学的发展。

1北极海冰快速变化的关键物理因素

北极海冰的变化与全球变暖几乎是同时发生的。20世纪70年代起，北极海冰覆盖范围呈不断减小的变化趋势，海冰厚度和海冰密集度也持续降低，北冰洋多年冰减少。海冰变化的早期主要是海冰厚度的变化，海冰覆盖率的变化并不显著，没有引起足够的注意。21世纪以来，海冰覆盖范围出现显著变化。2007年发生了北极海冰覆盖面积突然减少31%的事件，引起了北极科学界的高度关注。2012年，北极海冰又一次发生了骤减，海冰覆盖范围降到历史新低，是迄今观测到的最小海冰覆盖率。

最新的研究表明，2007年和2012年夏季北极海冰覆盖面积大幅度减少在过去1450年以来都是独一无二的。CMIPS模拟结果显示，在RCP8.5情景下，模式结果无一例外地表现出在未来20～40年会出现夏季无冰的北冰洋。海冰的减少被认为是北极放大现象的关键因素。海冰的减少不仅与气温升高有关，还受以下各种因素的影响：

1）随着北极气温的升高，海冰内部结构发生了微妙的变化。海冰吸收外界热量，冰晶体之间的卤水通道扩张，冰内部的固态、液态、气态成分比例不断发生变化。冰的结构体现为与以往不同的复合材料，冰的光学、热学、力学、电学、磁学等性质发生相应的变化。其中光学、热学性质的变化决定了海冰在生消过程中的热质平衡；力学性质变化决定了海冰在外界动力下的破碎过程，这些变化直接决定海冰快速变化过程因。

2）冰面融池是积雪融化的产物，迄今观测到夏季北极最大的融池覆盖率达到56%以上，对海冰的融化有不可忽视的影响。由于融池表面反照率低，融池水吸收的太阳短波辐射多，通过冲洗效应影响海冰的融化因，导致气—冰—海热力学结构发生变化，直接加快海冰的融化过程。近年来，通透的融池比例增大，海冰的大尺度应变特征也发生了变化，进而影响海冰的动力破碎过程。

3）积雪变化是海冰变化最重要的因素之一。如果春季积雪快速融化，会使海冰直接暴露在日光下，导致夏季海冰大量消融。如果春季积雪保留到夏季，会大幅削减到达海冰的太阳辐射，使大量海冰保存到下一年。由于积雪的观测手段很少，人们对积雪的了解很不充分。卫星遥感反演积雪信息主要是光学遥感和微波遥感两大类。光学遥感只能用于研究积雪的覆盖范围，而被动微波遥感可以反演0.5 m以下厚度的积雪。Markus等利用SSM/I微波辐射计数据反演积雪深度，与船测月平均积雪深度相比，相关系数为0.81，平均偏差为3.5 cm。美国国家冰雪数据中心（National Snow and Ice Data Center, NSIDC）发布了基于Aqua/AMSR-E数据反演的积雪深度产品。在北极，积雪深度反演的误差很大，尤其是对其准确性缺乏检验的手段。人们期待更准确的数据问世，以增加对积雪热力学作用的深入研究。

4）海冰的运动也是改变海冰特性的重要因素之一。北极海冰平均漂流场体现为穿极流和波弗特涡流2个主要特征。近年来随着海冰减少，北极海冰漂流速度增加，2004—2009年的冰速增大46%/10 a。北极中央区域冰速的变化被认为主要是由风场增强造成的，而北冰洋边缘海海冰加速则是由海冰变薄引起的。Wang等的研究表明，海冰漂流场变化的不仅是冰速，而且体现为漂流类型的变化。根据1978—2006年的漂流数据分析，海冰漂流可以分为4种主要流型：标准流型（38%），反气旋流型（15%）、气旋式流型（16%）以及反对称流型（15%）。这些流型表明，海冰的漂流有不同的辐聚辐散特征，对海冰的变化有多种影响。人们密切关注的是，当海冰进一步减退、密集度减小、冰厚变薄之后，海冰的漂流会有什么变化。

5）影响海冰漂流场变化的主要因素是大气环流的变化。海冰一方面受风应力的驱动而发生运动，另一方面又受到冰场内部的相互制约，二者并不完全一致，但有很高的相关性。北极涛动（The Aretie Oscillation, AO）指数是北极大气环流的重要指数。研究表明，当AO为正位相时，波弗特流涡较小，穿极流更靠近西北冰洋；而当AO为负位相时，波弗特流涡范围很大，穿极流向东北冰洋偏移。

综上所述，除了气温升高之外，海冰结构、冰面融池、冰面积雪和海冰运动构成了海冰融化的主要影响因素，其中大部分因素的作用还不清楚，有些参数的观测很困难，需要开发特殊的观测手段获取数据。在北极气温显著升高背景下，海冰内部结构发生了很大的变化，需要明确认识海冰结构的变化，并将其热力学特性的改变定量表达出来。北极的融池覆盖率升高会导致海冰迅速破碎，需要揭示融池本身的热力学特征及其对海冰的热力学和动力学过程的影响。北极的积雪在春季全部融化，是容易被忽视的因素，但事实上积雪的作用直接影响到夏季海冰的去留，需要深入揭示积雪与海冰变化的联系。此外，海冰厚度的变化、海冰的侧向融化和海冰漂移过程都是影响海冰变化的关键因素，相关的物理过程需要深入研究。

2北极海冰变化导致的主要海洋过程

事实上，北极的海洋变化是影响海冰变化的最重要因素之一。北极海冰范围和密集度减小使得冰间水道增加，穿过冰间水道进入海洋的太阳辐射能增加，导致海洋获得了更多的热量，是“北极放大”过程的主要能量来源。过去30年的海冰减退极大地改变了北冰洋上混合层的热收支。数值模拟的结果表明，北冰洋上层海洋在21世纪增暖能量的80%来自于海表面的热通量。北冰洋的海表面温度（Sea Surface Temperature, SST）从1995年左右开始出现升温，2000年之后更为突出，2007年夏季的SST距平高达5℃。在几乎全部被海冰覆盖的北极中央区，夏季海洋的上50 m层也有显著增温，混合层的温度能够高于冰点0.4℃。北极季节性无冰区面积年际差异很大，导致海—气间热通量发生较大的季节性和年际波动，对整个北冰洋热含量长期变化的贡献率接近1/3。北冰洋上层海洋增暖最重要的现象是次表层暖水的出现，后来国外将其称为近表层温度极大值(Near Surface Temperature Maximum)。次表层暖水发生在20～40 m深度范围内，温度在-0.5℃以上，是储存太阳辐射的一种特殊形式。1993—2009年，次表层暖水的温度上升了1.5℃。次表层暖水的热量释放会导致北极海冰提前融化和延后冻结，意味着季节性海冰区的范围正在扩大，对海洋热储存带来非常大的影响。计算表明，北冰洋夏季上层海洋变暖足以使冬季的海冰生长减少0.75 m，使秋季的结冰推迟2周至2个月。

虽然海洋在不断地增暖，但海洋实际增加的热含量并不多。海洋吸收的热量绝大多数通过湍流运动向上传输，这些热量被称为冰下海洋热通量。冰下海洋热通量有着显著的季节变化，冬季较小，在8月可以达到40～60 W/m2。在冰间水道中，海洋热通量会通过长波辐射、感热和潜热通量直接进入大气，成为影响大气热过程的主要因素，在北极放大过程中被称为“海洋强迫”。在海冰之下，海洋热通量中只有很少部分进入海冰，并通过海冰进入大气。以往认为穿过海冰的热通量为2 W/m2。后来的观测表明，这一数值被低估了近1倍。夏季到达冰下的海洋热通量远大于穿过海冰散热的热通量，导致大量热量在冰下积聚，直接造成海冰的底部融化，是海冰厚度减薄的主要因素。

海洋热通量的绝大部分能量来自太阳短波辐射，还有一部分来自海洋的热平流。海洋环流在2个方面导致海水热量的输运与再分配：一是将低纬度的暖水（太平洋水和大西洋水）输运到北冰洋；二是把北冰洋内部加热的水体重新分布，主要体现在表层环流对海洋热量的再分配。表层环流随风场变化，其细节结构还需要深入研究。通过白令海峡进入的太平洋入流，在夏季直接影响楚科奇海海冰融化，在冬季则成为保留在北极海冰之下的一个次表层海洋热源，对北冰洋太平洋扇区的海冰减退有重要贡献。实际上，太平洋水水层厚度只有几十米，入流流量只有1 Sv左右，携带的热量在融冰中很快耗尽，无法对北冰洋深处的海冰融化产生显著影响。真正影响大范围海冰的是开阔水域受到局地加热的水体，这些水体不断进入冰区加剧海冰融化。相比之下，来自弗莱姆海峡的大西洋入流水层厚度数百米，流量5 Sv以上，不仅深刻影响北冰洋中大西洋扇区的海冰，维系了大面积的冰间湖，而且通过对流潜沉到200 m以下，形成北极中层水，通过环极边界流输送到北冰洋各个海盆。北冰洋海盆区北极中层水的热量被盐跃层抑制不能上传，但在北冰洋边缘海域存在上升流，将暖水带到近表层海域，导致加拿大海盆外围的海冰大范围融化。

大西洋亚极地海区的强对流是全球热盐环流的主要动力，而北冰洋淡水含量变化是影响该海区对流和层化过程的重要因素。Proshutinsky等首次开展了针对北冰洋淡水含量的研究，此前并未引起关注的北冰洋淡水含量变化成为近年来的研究热点。北冰洋中心海区在20世纪呈现出咸化趋势，淡水以（239±270）km3/10 a的速度减少。但在20世纪末以来，淡水含量呈显著增加态势。到2010年，加拿大海盆淡水含量接近45800 km3，约占北冰洋淡水总量的60%，是北冰洋淡水的主要分布区域。研究发现，除2006年以外，2003—2008年夏季加拿大海盆淡水含量每年增加1 m以上厚度。夏季太平洋水的盐度范围已从1993年的变化为2008年的28～32。淡水含量的变化引起海面动力地形的改变，进而引起了环流的调整，改变着波弗特流涡的流型和密度结构。加拿大海盆中的淡水通过弗拉姆海峡和加拿大北极群岛进入北大西洋，引起了表面盐度降低和层化加强，成为影响北欧海和北大西洋对流过程以及全球海洋经向翻转环流的重要因素。

北冰洋常年存在的主盐跃层被称为永久性盐跃层。在北冰洋的中央区，特别是阿蒙森海盆和马可罗夫海盆，盐跃层的上部表现为温度保持在冰点附近，而盐度随深度显著增加的特殊温盐结构特征，被称为冷盐跃层。冷盐跃层的形成和变化一直是北冰洋研究的热点。在2000年前后，马可罗夫海盆的冷盐跃层经历了从消退到恢复的特殊变化，引起了广泛的关注。在加拿大海盆，由于太平洋水的汇入，盐跃层结构不同于冷盐跃层，而是表现为双跃层结构。近年的观测资料显示，在北冰洋次表层海水中还存在一个季节性盐跃层。夏季，随着海冰的消融，在20 m附近会出现一个低温低盐的盐跃层；秋季过后，该盐跃层会慢慢消失。这个次表层盐跃层是次表层暖水发生的必要条件。由于北冰洋存在多重的盐度跃层，每个盐跃层都会对垂直方向的热量传输起到抑制作用，下层的热量上不来，上层的热量下不去。因此，北冰洋有气候效应的水体实际上只有几十米厚。

北极的变化以海冰变化为主要特征，海洋的作用不那么直观。然而，海洋才是北极变化获取能量的关键因素，是太阳能的转换器和储存器。北极海洋的变化还有很多问题没有搞清楚，如北极上层海洋的温盐结构如何影响对太阳辐射的吸收？海洋内部能量如何在上层海洋中均匀化？海洋的能量如何在融冰和向大气传热之间进行分配？海洋储存的热量如何调控秋季的对流，延缓海冰的冻结？这些海洋过程对北极海冰变化是至关重要的，需要深入研究北极海冰减退引起的上层海洋热储存增加，北冰洋夏季热量储存的延迟释放及其对海冰的影响，北冰洋上层环流引起的热量平流输送与分配，北极上升流引起的中层水热量垂向输送，极地淡水含量的变化对海洋层化及动力高度变化的影响，北冰洋盐跃层结构变化及其对热量储存和转换的影响。

3北极正在发生的气候和天气变化

在过去30余年，北极的气温呈现持续增暖的趋势，21世纪以来北极的增暖幅度约为全球平均值的2倍，被称为“北极放大”现象。北极增暖的关键问题是热量从何而来。由于近年来太阳活动没有明显异常，北极增暖不是由地球之外的因素引起的，只能来源于地球系统内部。人们最早想到了可能是低纬度更多的热量进入了北极地区。然而，多年的观测结果表明，来自低纬度的热量确有变化，但对北极增暖的贡献不明显。因而，北极增暖的热量主要来自北极自身额外获得的能量。在太阳辐射强度基本保持不变的前提下，北极能量的增加与气候系统中的正反馈过程相联系。人们研究了各种可能的反馈过程，主要是冰雪反照率反馈（snow/ice-albedo feed-back）、水汽反馈（water vapor feedback）和云辐射反馈（cloud radiation feedback）3种。研究表明，水汽的作用并不构成正反馈，因为冰面的水汽总是处于饱和状态。云是直接影响太阳辐射的因素，其反馈作用最令人关注。云的反馈是很多反馈的组合，包括云分布、云中水含量、液滴大小、云温度、降雨、相变等多种过程引起的反馈网。1982—1999年卫星遥感得到的云数据表明，北极春季和夏季云量增大，而冬季云量减小。但是总体来看，云的变化并不是引起海冰减少的主要因素。研究表明，北极增暖的反馈主要是冰雪反照率反馈，即海冰减少导致海洋吸收热量的增加，这些热量释放给大气，引起气温增加。后来将这种反馈更为准确地称为海冰—气温反馈（ice temperature feedback）。

北极气温升高同时引起大气环流的复杂变化，通过对海面气压场（Sea Level Pressure, SLP）时间序列数据进行EOF分析，可以得到AO的空间分布和时间系数，后者称为北极涛动指数（Aretie Oscillation Index, AOI）。由于北极变暖，北极涛动的强度也显著下降，AOI在最近10年呈现弱的负位相。Zhao等网研究了北极涛动的空间变化，确定了北极涛动的空间变化指数。结果表明，1950年以来的北极涛动空间变化大体可分为3个阶段：1950—1970年是正位相阶段，代表全球变暖以前的情形；1970—1998年是负位相阶段，大体代表全球变暖但北极没有明显变暖的情形。1998年至今是正负位相不明显的阶段，代表北极变暖的阶段，表明北极涛动的影响范围变小。这段时间AO与北极海冰的变化趋势并不一致，二者之间的关系表现出明显的“退藕（decou-pled）”现象。

北极上空大气环流异常的优势模态除AO外，还存在偶极子型（Dipole Anomaly, DA）的东西半球振荡。最近的研究结果表明，2007年北极海冰急剧减少后AO的响应越来越弱，且更偏向于出现负位相，海冰与大气的藕合关系更多地体现在与DA的藕合相关上。Liu等的研究表明，最近几年北极海冰快速减少引起的大气环流异常响应并不是传统的AO模态，也不是稳定的DA模态，而是一种更为复杂的大气环流异常型，导致了近年来北半球极端降雪和严寒频发，但其复杂的影响途径仍需进一步的深入研究。近几十年，AO/NAO向负位相的转变表征了对流层西风带的减弱，这种大气环流的变化可以引起北半球大陆的变冷。大气环流主要模态的空间形态变化也会引起陆地变冷。研究表明，北极放大效应可加强大气环流的这些变化。

在北极增暖背景下，不仅大气环流发生异常，中尺度的气旋活动风暴轴向北移动，中纬度地区进入北极地区的气旋频率和强度增强，北极地区生成的气旋活动频率和强度也有增强的趋势。北极气旋活动的增强导致海冰迅速减少，引发更强烈的风暴潮画。

对大气而言，海洋的作用无比重要，是大气变化的主要能量来源，北极气候的变化机制被称为海洋强迫。在海洋强迫下，需要解决的科学问题很多，最重要的关键问题有：北极海冰快速减退条件下的气—冰—海藕合过程，海洋强迫对北极放大正反馈机制的贡献，北极天气尺度系统变化及其在北极放大过程中的作用，北极云雾对北极放大的负反馈作用。通过相关的研究，才能深入认识北极海—冰—气系统正在发生的变化。

4北极变化对北半球和中国气候的影响

北极气候的变化导致了北极能量新的平衡，北极作为寒极的性质发生了重大变化，受到影响的不仅是北极地区，而且对中纬度地区产生巨大影响，主要体现在风暴路径以及行星波及其能量传播。

已有研究表明，北半球大气环流对北极海冰异常的响应存在直接和间接2种。直接响应主要是北极局地的响应，引起春季积雪的减少并导致海冰减退。北极海冰对中国气候的影响可以通过大气环流异常的间接响应来实现。

经过多年的资料收集和思索，Overland等提出了北极变化与全球变化相互影响的机理，认为全球变暖启动了北极海冰的减少，进而发生海洋吸收热量增加和加热大气的正反馈过程，反过来影响全球变暖过程。具体而言，中高纬度大气罗斯贝波理论可以解释北极对中纬度影响的机制。随着北极变暖海冰融化，北极放大效应最主要的一个表现是北极寒极的变暖，热带与极区温差减小，导致罗斯贝波加深（振幅增大）和带状风减弱，进而引起罗斯贝波传播速度减慢，使得中纬度天气系统持续时间更长，造成中纬度极端天气事件增多，干旱、热浪、严寒等更为严重。罗斯贝波加深的最常见表现就是大气阻塞高压或西风槽的发展和加强。关于罗斯贝波的加深机理，以往的研究中主要有大气内部动力过程和非绝热加热等外部强迫2种观点，其中大气内部动力过程主要包括波流相互作用、共振理论、多平衡态理论、非线性孤立波理论、偶极子理论、天气尺度涡旋的激发以及天气尺度波与行星尺度波的非线性相互作用理论等几种理论，但这些理论基本上都是基于准地转近似理论框架，对于极区的强非线性效应的贡献考虑不足。由于极区地球自转效应增强，极区的涡旋特征类似于台风外围涡旋罗斯贝波的效应。因此，建立合适的极区非线性动力学模型来研究罗斯贝波加深的机理是一项不可或缺的工作。

我国学者指出AO/NAO能通过影响西伯利亚高压进而影响东亚冬季风，表明北极海冰快速消融后北半球中高纬度大气环流的异常响应已由原来的纬向型（0波结构的AO）向较高频的经向型（DA为1波定常波结构）过渡，大气优势模态对北极放大的响应表现出更复杂的异常环流型，大气对极区这种异常加热的响应可能会产生高纬度定常波的响应，可以向南形成几支稳定的气流通道引导冷空气南下，进而影响中纬度地区的气候变化。

通过大气再分析资料分析、海表温度资料分析以及大气环流数值模拟发现，北极秋季海冰减少可以引起高纬高压系统的发展，甚至有利于阻塞高压的发展与维持，这一机制可能是中国2008年1～2月出现严重的持续性冻雨的主要原因。在北极放大的背景下，欧亚大陆反气旋活动强度出现了明显的增强趋势，反气旋强度变化与欧亚中纬度地区的极端温度事件日数存在显著相关，其中与东亚

特别是我国东部地区关系尤为明显。我国大部分地区位于中纬度气候带，气候系统深受北极过程的影响。遥远的北极海冰的异常变化如何影响中国的气候变化，目前仍然是一个需要深入研究的问题。我们认为，北极影响我国气候的因素事实上是环球罗斯贝波的变异问题，不仅与北极问题有关，也与热带过程有关；不仅与中国过程有关，也与欧洲和北美的问题有关。北极变化对我国气候和天气的影响机理还很不清楚，需要深入研究大气对极区异常加热外强迫的定常波响应特征、极区涡旋罗斯贝波的动力特征及其在中高纬度罗斯贝波加深过程中的作用、高纬度罗斯贝波加深的非线性机理、北极放大过程对北极涛动长期变化的影响等。通过对这些过程的认识，搞清北极变化对我国气候变化和相关灾害性天气事件的影响方式。

5讨论

当北极快速变化展现在人们面前的时候，科学界受到极大的震撼，所有的科学家都没有预测出北极的快速变化，所有的模式都没有能模拟出海冰的快速减退。人们发现，对北极海冰、海洋和大气过程的理解还没有真正深入到海冰变化的物理实质。最近5年的时间里，一些科学家反思了北极研究的现状和问题，认为还是应该从大的科学问题着眼，从具体的物理过程入手，重新认识变化了的北极。科学界将北极海冰变化的原因归结于全球气候变化和在北极发生的各种正反馈，认为是这些正反馈导致海洋吸收了更多的热量，加强了气—冰—海之间的相互作用，引起海冰的进一步减退。已有的研究表明，这种研究思路是正确的。然而认识这些正反馈却并不容易，因为北极发生的主要正反馈都涉及到海洋和海冰变化的物理过程，而这些过程的大部分并没有搞清楚，甚至知之甚少。因此，近年来关于北极变化正反馈的研究进展并不大。在深入研究北极发生的物理过程，尤其要研究北极变暖之后各种变性的物理过程和新产生的物理过程，探索北极变化的物理实质。研究基础的物理过程，只靠同化数据和再分析数据是不够的，需要有针对性地开展大规模现场观测，获得北极变化过程的实测数据，才能真正反映和认识这些物理过程。

与此同时，北极变化对我国气候的影响也逐步显现。已有的研究表明，在冬季，北极的变化通过大气环流影响我国北方的气候。我国北方冬季普遍增暖和极端严寒天气都与北极的作用密不可分。北极变化改变了大气环流，对沙尘和雾霾的输送方向产生重要影响。春季和秋季是冷暖气团消长时期，通常与锋区的活动和北方的干旱过程相联系。初步研究表明，我国2008年和2011年南方的大规模冻雨与北极海冰的变化密切相关，而且同时发生的北方干旱导致华北主要产粮区冬小麦大幅度减产。北极的可能影响还有很多，如对海上风暴、夏季酷热、秋季降雪的影响等，其中大部分尚未充分研究。

北极对我国气候的影响会产生重大的社会影响。首先是对主要产粮区气候的影响，直接威胁到我国的粮食安全。其次是气候灾害的发生，对全国产生多种可能的灾害。对北极变化的深入研究是推动北极变化对我国气候影响研究的主要渠道，攻克一系列尚未解决的科学问题，为解决北极影响我国的过程和机理、提高气候预测精度和水平奠定坚实的基础，支持国家有关部门提出切实的措施和必要的对策，应对北极变化对我国气候的强烈影响。

【作者单位：中国海洋大学；南京信息工程大学；大连理工大学】

（摘自《地球科学进展》2015年第9期）

·高被引论文摘要·

被引频次：110

IPCC第一工作组第五次评估报告对全球气候变化认知的最新科学要点

沈永平，王国亚

2013年9月27日，在瑞典首都斯德哥尔摩，联合国政府间气候变化专门委员会第一工作组第五次评估报告《Climate Change 2013: The Physical Science Basis》决策者摘要（Summary for Policymakers, SPM）发布，随后于9月30日公布了报告全文。报告指出，全球气候系统变暖的事实是毋庸置疑的，自1950年以来，气候系统观测到的许多变化是过去几十年甚至近千年以来史无前例的。全球几乎所有地区都经历了升温过程，变暖体现在地球表面气温和海洋温度的上升、海平面的上升、格陵兰和南极冰盖消融和冰川退缩、极端气候事件频率的增加等方面。全球地表持续升温，1880—2012年全球平均温度己升高0.85℃[0.65～1.06℃]；过去30 a，每10 a地表温度的增暖幅度高于1850年以来的任何时期。在北半球，1983—2012年可能是最近1400 a来气温最高的30 a。特别是1971—2010年间海洋变暖所吸收热量占地球气候系统热能储量的90%以上，海洋上层（0～700 m）己经变暖。与此同时，1979—2012年北极海冰面积每10 a以3.5%～4.1%的速度减少；自20世纪80年代初以来，大多数地区多年冻土层的温度己升高。全球气候变化是由自然影响因素和人为影响因素共同作用形成的，但对于1950年以来观测到的变化，人为因素极有可能是显著和主要的影响因素。目前，大气中温室气体浓度持续显著上升，CO2、CH4和N2O等温室气体的浓度己上升到过去800 ka来的最高水平，人类使用化石燃料和土地利用变化是温室气体浓度上升的主要原因。在人为影响因素中，向大气排放CO2的长期积累是主要因素，但非CO2温室气体的贡献也十分显著。控制全球升温的目标与控制温室气体排放的目标有关，但由此推断的长期排放目标和排放空间数值在科学上存在着很大的不确定性。

IPCC WGI AR5；气候变化；未来变化；温室气体；关键结论

来源出版物：冰川冻土, 2013, 35(5): 1068-1076

被引频次：91

IPCC第五次评估报告第一工作组报告的亮点结论

秦大河，Thomas Stocker

摘要：IPCC第五次评估报告（AR5）第一工作组（WGI）报告的亮点结论，是过去7年全世界气候变化科学研究成果凝练出来的精华。20世纪50年代以来全球气候变暖的一半以上是人类活动造成的。1971年以来人为排放温室气体产生热量的93%进入了海洋，海洋还吸收了大约30%人为排放的CO2，导致海表水pH值下降了0.1，等等。采用全球耦合模式比较计划第五阶段（CMIP5）的模式，预估未来全球气候变暖仍将持续，21世纪末全球平均地表温度在1986—2005年的基础上将升高0.3～4.8℃。限制气候变化需要大幅度持续减少温室气体排放。如果将1861—1880年以来的人为CO2累积排放控制在1000 Gt C，那么人类有超过66%的可能性把未来升温幅度控制在2℃以内（相对于1861—1880年）。

关键词：气候变化；温室气体；IPCC AR5；WGI

来源出版物：气候变化研究进展, 2014, 10(1): 1-6

被引频次：39

北极海冰对大气环流与气候影响的观测分析和试验研究

黄士松，杨修群，谢倩

摘要：文主要根据1953—1977年资料，从观测分析和数值试验两方面研究了北极海冰覆盖面积异常对全球的大气环流和气候、特别是对中国气候的影响，发现北极海冰的影响可与中东赤道太平洋海温异常的影响相比拟，甚或可以超过，指出在气候和长期天气预报研究工作中，极冰变异及其影响需要很好重视。

关键词：北极海冰；大气环流；数值试验

来源出版物：海洋学报, 1992, 14(6): 32-46

被引频次：34

秋—冬季节北极海冰对冬季西伯利亚高压的影响

武炳义，苏京志，张人禾

摘要：冬季西伯利亚高压强度与前期秋到冬季北冰洋东部、欧亚大陆北部边缘海区海冰密集度呈现显著的负相关关系。研究结果显示，秋冬季北冰洋海冰密集度与同期海表温度异常可导致冬季西伯利亚高压与欧亚大陆中高纬度及东亚的地表气温异常。数值试验结果进一步证实该结论，并且所有的数值试验结果一致表明，较低的海冰密集度能导致欧亚大陆中高纬度地表温度负异常。本文提出了一种机制来解释秋冬季北极海冰密集度和冬季西伯利亚高压的联系。9月份海冰密集度为预测冬季西伯利亚高压提供了一个潜在的前期信号，而若由单纯的热带海温异常则不能预测冬季西伯利亚高压强度。在近20 a来（1990—2009年）冬季西伯利亚高压呈现增强的趋势，并伴随着亚洲大陆中高纬度地表温度的降温趋势，从而导致近年来东亚严冬频发。最后，讨论了冬季西伯利亚高压和地表气温短期趋势的成因。

关键词：北极海冰；西伯利亚高压；东亚气候；严冬频发

来源出版物：科学通报, 2011, 56(27): 2335-2343

被引频次：34

近30 a北极海冰异常变化趋势

张璐，张占海，李群，等

摘要：在过去30 a间，北极气候发生了前所未有的异常变化，北极海冰变化更是经历了令人瞩目的、从平缓到突变的缩减过程，因此，北冰洋及其海冰的研究得到广泛的重视。综述当前国内外有关北极海冰快速变化的研究工作，对这些大气的现场观测和卫星遥感资料的分析，以及一些全球和区域气候模拟的结果，基本上一致地指出了近30 a来北极海冰的快速衰减趋势，尤其是夏季北极海冰正以每10 a超过10%的变化幅度快速减少。从海冰的基本物理特征、与大气海洋相互作用的物理过程、及其对全球和北极气候变化的响应和反馈机制，研究形成这种快速变化的因子——海表面气温增暖，太平洋与大西洋入流的热盐性质变化，以及大气环流模态的影响等。

关键词：北极；海冰范围；突变；气候

来源出版物：极地研究, 2009, 21(4): 344-352

被引频次：34

北极海冰变化的时间和空间型

汪代维，杨修群

摘要：利用44 a（1951—1994年）北极海冰密度逐月资料，分析提出了一种与北极冰自然季节变化相吻合的分季法，并根据这种分季法，使用EOF分解，揭示了北极各季海冰面积异常的特征空间型及其对应的时间变化尺度。结果表明：1）北极冰面积异常变化的关键区，冬季（2—4月）主要位于北大西洋一侧的格陵兰海、巴伦支海和戴维斯海峡以及北太平洋一侧的鄂霍次克海和白令海，夏季（8—10月）则主要限于从喀拉海、东西伯利亚海、楚科奇海到波佛特海的纬向带状区域内，格陵兰海和巴伦支海是北极海冰面积异常变化的最重要区域；2）春（5—7月）、秋（11月—次年1月）季各主要海区海冰面积异常基本呈同相变化，夏季东西伯利亚海、楚科奇海、波佛特海一带海冰面积异常和喀拉海呈反相变化，而冬季巴伦支海、格陵兰海海冰面积异常和戴维斯海峡、拉布拉多海、白令海、鄂霍次克海的海冰变化呈反相变化；3）北极冰总面积过去44 a来确实经历了一种趋势性的减少，并且叠加在这种趋势变化之上的是年代尺度变化，其中春季（5—7月）海冰面积异常变化对年平均北极冰总面积异常变化作出了主要贡献；4）位于北太平洋一侧极冰面积异常型基本具有半年的持续性，而位于北大西洋一侧极冰面积异常型具有半年至一年的持续性。

关键词：北极海冰；长期趋势；年代尺度变化；持续性

来源出版物：气象学报, 2002, 60(2): 129-138

被引频次：30

北极海冰的厚度和面积变化对大气环流影响的数值模拟

武炳义，黄荣辉，高登义

摘要：文中利用中国科学院大气物理研究所设计的两层大气环流模式，模拟研究了北极海冰厚度和面积变化对大气环流的影响，尤其是对东亚区域气候变化的影响。模式中海冰厚度处理趋于合理分布吗，导致东亚冬、夏季风偏强，使冬季西伯利亚高压和冰岛低压的模拟结果更趋合理；另一方面，海冰厚度变化可以激发出跨越欧亚大陆的行星波传播，在低纬度地区，该行星波由西太平洋向东太平洋地区传播；海冰厚度变化对低纬度地区的对流活动也有影响。冬季北极巴伦支海海冰变化对后期大气环流也有显著的影响。数值模拟结果表明：冬季巴伦支海海冰偏多（少）时，春季（4—6月）北太平洋中部海平面气压升高（降低），阿留申低压减弱（加深），有利于春季白令海海冰偏少（多）；而夏季，亚洲大陆热低压加深（减弱），500 hPa西太平洋副热带高压位置偏北（南）、强度偏强（弱），东亚夏季风易偏强（弱）。

关键词：北极海冰；厚度；东亚季风；巴伦支海；数值模拟

来源出版物：气象学报, 2001, 59(4): 414-428

被引频次：27

宁夏春季沙尘暴与北极海冰之间的遥相关关系

杨建玲，何金海，赵光平

摘要：根据宁夏沙尘暴发生次数资料、北极海冰密集度资料和NCEP/NCAR再分析500、850 hPa高度场、风场资料，得出了宁夏春季沙尘暴发生次数的变化规律及其与北极海冰面积之间的年代际和年际相关关系，发现宁夏春季沙尘暴发生次数与欧亚大陆北部的喀拉海、巴伦支海和格陵兰海冰面积之间存在较显著的年代际、年际相关关系。通过合成和相关分析知，宁夏春季沙尘暴偏多、偏少状况有明显不同的环流背景场，秋季格陵兰海冰异常变化通过影响其后一段时间的大气环流背景场，从而对宁夏沙尘暴产生影响。初步得出当格陵兰海秋季海冰面积增（减小），次年春季蒙古至西伯利亚一带500、850 hPa高压场降低（升高），风场有明显的气旋性（反气旋性）特点，在宁夏至新疆一带西风明显偏强（偏弱），说明冷空气活动次数偏多（少），对应宁夏春季沙尘暴发生次数偏多（少）。通过海冰将全球气候变暖和宁夏（我国北方）沙尘暴总减少趋势联系起来，初次提出在环境总体恶化情况下，我国沙尘暴发生次数总体趋于减少，很可能是全球气候变暖所致。

关键词：北极海冰；宁夏；沙尘暴；遥相关

来源出版物：南京气象学院学报, 2003, 26(3): 296-307

被引频次：27

南、北极海冰的长期变化趋势及其与大气环流的联系

赵玉春，孙照渤，王叶红

摘要：采用南、北极海冰面积指数1°×1°经纬度格点资料及海平面气压资料，运用多种统计方法，研究了南、北极海冰的长期变化趋势、突变特征及其与大气环流的联系，发现近年来南极冬、春、秋季海冰逐渐减少，夏季海冰逐渐增加；北极春、夏、秋季海冰均不同程度地减少，冬季海冰变化趋势不明显；南、北极各季海冰的年际变化均存在一定的突发性，大气环流在海冰突变年前后有显著的差异。

关键词：海冰；突变；大气环流

来源出版物：南京气象学院学报, 2001, 24(1): 119-126

被引频次：27

与北大西洋接壤的北极海冰和年际气候变化

武炳义，黄荣辉，高登义

摘要：冬季与北大西洋接壤的北极海冰面积变化与北大西洋区域气候变化有着非常密切的联系。当冬季北大西洋涛动指数处于异常偏高（低）时期，冰岛低涡加深（减弱）位置偏北（南），北大西洋副热带高压也偏强（弱），并且位置也偏北（南），导致中纬度纬向西风偏强（弱），受其影响中纬度北大西洋海温升高（降低），因而增强（减弱）暖洋流向高纬度区域输送，流入巴伦支海的北大西洋海水增多（减少），致使巴伦支海南部混合层水温偏高（偏低）；同时，大气温度场分布也表明，欧洲北部及其相邻的北极区域增暖（变冷）以及巴芬湾、戴维斯海峡附近区域气温降低（升高），致使喀拉海、巴伦支海海冰减少（增多）以及巴芬湾、戴维斯海峡海冰增加（减少）。

关键词：冬季；北大西洋涛动；海冰面积

来源出版物：科学通报, 2000, 45(18): 1993-1998

被引频次：3034

Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century

Rayner, NA; Parker, DE; Horton, EB; et al.

Abstract: We present the Met Office Hadley Centre’s sea ice and sea surface temperature(SST) data set, HadISST1, and the nighttime marine air temperature(NMAT) data set, HadMAT1. HadISST1 replaces the global sea ice and sea surface temperature(GISST) data sets and is a unique combination of monthly globally complete fields of SST and sea ice concentration on a 1degrees latitude-longitude grid from 1871. The companion HadMAT1 runs monthly from 1856 on a 5 degrees latitude-longitude grid and incorporates new corrections for the effect on NMAT of increasing deck(and hence measurement) heights. HadISST1 and HadMAT1 temperatures are reconstructed using a two-stage reducedspace optimal interpolation procedure, followed by superposition of quality-improved gridded observations onto the reconstructions to restore local detail. The sea ice fields are made more homogeneous by compensating satellite microwave-based sea ice concentrations for theimpact of surface melt effects on retrievals in the Arctic and for algorithm deficiencies in the Antarctic and by making the historical in situ concentrations consistent with the satellite data. SSTs near sea ice are estimated using statistical relationships between SST and sea ice concentration. HadISST1 compares well with other published analyses, capturing trends in global, hemispheric, and regional SST well, containing SST fields with more uniform variance through time and better month-to-month persistence than those in GISST. HadMAT1 is more consistent with SST and with collocated land surface air temperatures than previous NMAT data sets.

来源出版物：Journal of Geophysical Research-Atmospheres, 2003, 108(D14): 1063-1082

被引频次：772

The role of sea ice and other fresh water in the Arctic circulation

Aagaard K; Carmack EC

Abstract: Salinity stratification is critical to the vertical circulation of the high-latitude ocean. We here examine the control of the vertical circulation in the northern seas, and the potential for altering it, by considering the budgets and storage of fresh water in the Arctic Ocean and in the convective regions to the south. We find that the presentday Greenland and Iceland seas, and probably also the Labrador Sea, are rather delicately poised with respect to their ability to sustain convection. Small variations in the fresh water supplied to the convective gyres from the Arctic Ocean via the East Greenland Current can alter or stop the convection in what may be a modern analog to the halocline catastrophes proposed for the distant past. The North Atlantic salinity anomaly of the 1960s and 1970s is a recent example; it must have had its origin in an increased fresh water discharge from the Arctic Ocean. Similarly, the freshening and cooling of the deep North Atlantic in recent years is a likely manifestation of the increased transfer of fresh water from the Arctic Ocean into the convective gyres. Finally, we note that because of the temperature dependence of compressibility, a slight salinity stratification in the convective gyres is required to efficiently ventilate the deep ocean.

来源出版物：Journal of Geophysical Research Atmospheres, 1989, 94(C10): 14485-14498

被引频次：611

Accelerated decline in the Arctic Sea ice cover

Comiso, Josefino C; Parkinson, Claire L; Gersten, Robert; et al.

Abstract: Satellite data reveal unusually low Arctic sea ice coverage during the summer of 2007, caused in part by anomalously high temperatures and southerly winds. The extent and area of the ice cover reached minima on 14 September 2007 at 4.1×106km2and 3.6×106km2, respectively. These are 24% and 27% lower than the previous record lows, both reached on 21 September 2005, and 37% and 38% less than the climatological averages. Acceleration in the decline is evident as the extent and area trends of the entire ice cover(seasonal and perennial ice) have shifted from about -2.2% and -3.0% per decade in 1979 1996 to about -10.1% and -10.7% per decade in the last 10 years. The latter trends are now comparable to the high negative trends of -10.2% and -11.4% per decade for the perennial ice extent and area, 1979-2007.

来源出版物：Geophysical Research Letters, 2008, 35(1): L01703

被引频次：568

Thinning of the Arctic sea-ice cover

Rothrock, DA; Yu, Y; Maykut, GA; et al.

Abstract: Comparison of sea-ice draft data acquired on submarine cruises between 1993 and 1997 with similar data acquired between 1958 and 1976 indicates that the mean ice draft at the end of the melt season has decreased by about 1.3 m in most of the deep water portion of the Arctic Ocean, from 3.1 m in 1958-1976 to 1.8 m in the 1990s. The decrease is greater in the central and eastern Arctic than in the Beaufort and Chukchi seas. Preliminary evidence is that the ice cover has continued to become thinner in some regions during the 1990s.

来源出版物：Geophysical Research Letters, 1999, 26(23): 3469-3472

被引频次：542

Arctic sea ice decline: Faster than forecast

Stroeve, Julienne; Holland, Marika M; Meier, Walt; et al.

Abstract: From 1953 to 2006, Arctic sea ice extent at the end of the melt season in September has declined sharply. All models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report(IPCC AR4) show declining Arctic ice cover over this period. However, depending on the time window for analysis, none or veryfew individual model simulations show trends comparable to observations. If the multi-model ensemble mean time series provides a true representation of forced change by greenhouse gas(GHG) loading, 33%-38% of the observed September trend from 1953-2006 is externally forced, growing to 47%-57% from 1979-2006. Given evidence that as a group, the models underestimate the GHG response, the externally forced component may be larger. While both observed and modeled Antarctic winter trends are small, comparisons for summer are confounded by generally poor model performance.

来源出版物：Geophysical Research Letters, 2007, 34(9): L09501

被引频次：382

Arctic sea ice extents, areas, and trends, 1978-1996

Parkinson, CL; Cavalieri, DJ; Gloersen, P; et al.

Abstract: Satellite passive-microwave data for November 1978 through December 1996 reveal marked seasonal, regional, and interannual variabilities, with an overall decreasing trend of −34300±3700 km2/yr(−2.8%/decade) in Arctic sea ice extents over the 18.2-year period. Decreases occur in all seasons and on a yearly average basis, although they are largest in spring and smallest in autumn. Regionally, the Kara and Barents Seas have the largest decreases, at −15200±1900 km2/yr(−10.5%/decade), followed by the Seas of Okhotsk and Japan, the Arctic Ocean, Greenland Sea, Hudson Bay, and Canadian Archipelago. The yearly average trends for the total, the Kara and Barents Seas, and the Seas of Okhotsk and Japan all have high statistical significance, with the null hypothesis of a 0 slope being rejected at a 99% confidence level. Regions showing increasing yearly average ice extents are Baffin Bay/Labrador Sea, the Gulf of St. Lawrence, and the Bering Sea, with only the increases in the Gulf of St. Lawrence being statistically significant at the 99% level. Hemispheric results for sea ice areas exhibit the same −2.8%/decade decrease as for ice extents and hence a lower absolute decrease(−29500±3800 km2/yr), with the ice-free area within the ice pack correspondingly decreasing at −4800±1600 km2/yr. Confidence levels for the trends in ice areas and ice-free water areas exceed 99% and 95%, respectively. Nonetheless, interannual variability is high, and, for instance, the Arctic Ocean ice extents have a positive trend 1990–1996, in spite of their negative trend for the time period as a whole.

来源出版物：Journal of Geophysical Research Oceans, 1999, 104(C9): 20837-20856

被引频次：374

Response of sea ice to the Arctic oscillation

Rigor, IG; Wallace, JM; Colony, RL

Abstract: Data collected by the International Arctic Buoy Programme from 1979 to 1998 are analyzed to obtain statistics of sea level pressure(SLP) and sea ice motion(SIM). The annual and seasonal mean fields agree with those obtained in previous studies of Arctic climatology. The data show a 3-hPa decrease in decadal mean SLP over the central Arctic Ocean between 1979-1988 and 1989-1998. This decrease in SLP drives a cyclonic trend in SIM, which resembles the structure of the Arctic Oscillation(AO). Regression maps of SIM during the wintertime(January-March) AO index show 1) an increase in ice advection away from the coast of the East Siberian and Laptev Seas, which should have the effect of producing more new thin ice in the coastal flaw leads; 2) a decrease in ice advection from the western Arctic into the eastern Arctic; and 3) a slight increase in ice advection out of the Arctic through Fram Strait. Taken together, these changes suggest that at least part of the thinning of sea ice recently observed over the Arctic Ocean can be attributed to the trend in the AO toward the high-index polarity. Rigor et al. showed that year-to-year variations in the wintertime AO imprint a distinctive signature on surface air temperature(SAT) anomalies over the Arctic, which is reflected in the spatial pattern of temperature change from the 1980s to the 1990s. Here it is shown that the memory of the wintertime AO persists through most of the subsequent year: spring and autumn SAT and summertime sea ice concentration are all strongly correlated with the AO index for the previous winter. It is hypothesized that these delayed responses reflect the dynamical influence of the AO on the thickness of the wintertime sea ice, whose persistent “footprint” is reflected in the heat fluxes during the subsequent spring, in the extent of open water during the subsequent summer, and the heat liberated in the freezing of the open water during the subsequent autumn.

来源出版物：Journal of Climate, 2002, 15(18): 2648-2663

被引频次：350

Two circulation regimes of the wind driven Arctic Ocean

Proshutinsky, AY; Johnson, MA

Abstract: The major goal of this paper is to demonstratethe existence in the Arctic Ocean of two regimes of wind-forced circulation. We simulated the vertically averaged currents, sea level heights, and ice drift in the Arctic Ocean from 1946 to 1993 using a two-dimensional, wind-forced, barotropic model that includes frictional coupling between the ocean and ice. The model has a spatial resolution of 55.5 km and is driven by winds, river runoff, and an imposed but realistic sea level slept: Between the Pacific and the Atlantic Oceans. There is a good agreement between velocities from observed buoy motions and velocities of modeled ice drift even though the model lacks Ocean baroclinicity and ice thermodynamics. The results indicate that wind-driven motion in the central Arctic alternates between anticyclonic and cyclonic circulation, with each regime persisting for 5-7 years, based upon our analysis of the modeled sea level and ice motion. Anticyclonic wind-driven motion in the central Arctic appeared during 1946-1952, 1958-1963, 1972-1979, and 1984-1988, and cyclonic motion appeared during 1953-1957, 1964-1971, 1980-1983, and 1989-1993. Shifts from one regime to another are forced by changes in the location and intensity of the Icelandic low and the Siberian high. The two regimes may help explain the significant, basin-scale changes ih the Arctic’s temperature and salinity structure observed recently; the Great Salinity Anomaly; and the variability of ice conditions iii the Arctic Ocean.

来源出版物：Journal of Geophysical Research-Oceans, 1997, 102(C6): 12493-12514

被引频次：325

The central role of diminishing sea ice in recent Arctic temperature amplification

Screen, James A; Simmonds, Ian

Abstract: The rise in Arctic near-surface air temperatures has been almost twice as large as the global average in recent decades-a feature known as ‘Arctic amplification’. Increased concentrations of atmospheric greenhouse gases have driven Arctic and global average warming; however, the underlying causes of Arctic amplification remain uncertain. The roles of reductions in snow and sea ice cover and changes in atmospheric and oceanic circulation, cloud cover and water vapour are still matters of debate. A better understanding of the processes responsible for the recent amplified warming is essential for assessing the likelihood, and impacts, of future rapid Arctic warming and sea ice loss. Here we show that the Arctic warming is strongest at the surface during most of the year and is primarily consistent with reductions in sea ice cover. Changes in cloud cover, in contrast, have not contributed strongly to recent warming. Increases in atmospheric water vapour content, partly in response to reduced sea ice cover, may have enhanced warming in the lower part of the atmosphere during summer and early autumn. We conclude that diminishing sea ice has had a leading role in recent Arctic temperature amplification. The findings reinforce suggestions that strong positive ice-temperature feedbacks have emerged in the Arctic, increasing the chances of further rapid warming and sea ice loss, and will probably affect polar ecosystems, ice-sheet mass balance and human activities in the Arctic.

来源出版物：Nature, 2010, 464(7293): 1334-1337

被引频次：325

Future abrupt reductions in the summer Arctic sea ice

Holland, Marika M; Bitz, Cecilia M; Tremblay, Bruno

Abstract: We examine the trajectory of Arctic summer sea ice in seven projections from the Community Climate System Model and find that abrupt reductions are a common feature of these 21st century simulations. These events have decreasing September ice extent trends that are typically 4 times larger than comparable observed trends. One event exhibits a decrease from 6 million km2to 2 million km2in a decade, reaching near ice-free September conditions by 2040. In the simulations, ice retreat accelerates as thinning increases the open water formation efficiency for a given melt rate and the ice-albedo feedback increases shortwave absorption. The retreat is abrupt when ocean heat transport to the Arctic is rapidly increasing. Analysis from multiple climate models and three forcing scenarios indicates that abrupt reductions occur in simulations from over 50% of the models and suggests that reductions in future greenhouse gas emissions moderate the likelihood of these events.

来源出版物：Geophysical Research Letters, 2006, 33(23): L23503

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北极海域渔业资源开发现状及对策

焦敏，陈新军，高郭平

摘要：随着全球变暖，北极海冰覆盖面积逐年减少。在全球海洋渔业资源衰退的大背景下，北极渔业资源的开发和合理利用备受世界各国关注，越来越多的国际组织和科学家开始对北极渔业进行探索研究。由于北极地区环境恶劣，海洋鱼类的种类和资源量相比其他地区较少，但随着北极海冰的融化，北极渔业资源开发和利用成为可能，北极潜在的未充分开发利用的渔业资源正吸引着有关国家的高度关注。为此，本文通过收集国内外相关文献，对北极渔业种类、资源状况及其开发现状进行了分析，同时提出了中国参与北极渔业资源开发和利用的对策与建议。

关键词：北极海域；渔业资源；捕捞量；发展对策

来源出版物：极地研究, 2015, 27(2): 219-227

北极海冰减退引起的北极放大机理与全球气候效应

赵进平，史久新，王召民

摘要：自20世纪70年代以来，全球气温持续增高，对北极产生了深刻的影响。21世纪以来，北极的气温变化是全球平均水平的2倍，被称为“北极放大”现象。北极海冰覆盖范围呈不断减小的趋势，2012年北极海冰已经不足原来的40%，如此大幅度的减退是过去1450 a以来独有的现象。科学家预测，不久的将来，将会出现夏季无冰的北冰洋。全球变暖背景下北极内部发生的正反馈过程是北极放大现象的关键，不仅使极区的气候发生显著变化，而且对全球气候产生非常显著的影响，导致很多极端天气气候现象的发生。北极科学的重要使命之一是揭示这些正反馈过程背后的机理。北极放大有关的重大科学问题主要与气—冰—海相互作用有关，海冰是北极放大中最活跃的因素，要明确海冰结构的变化，充分考虑融池、侧向融化、积雪和海冰漂移等因素，将海冰热力学特性的改变定量表达出来。海洋是北极变化获取能量的关键因素，是太阳能的转换器和储存器，要认识海洋热通量背后的能量分配问题，即能量储存与释放的联系机理，认识淡水和跃层结构变化对海气耦合的影响。全面认识北极气候系统的变化是研究北极放大的最终目的，要揭示气—冰—海相互作用过程、北极海洋与大气之间反馈的机理、北极变化过程中的气旋和阻塞过程、北极云雾对北极变化的影响。在对北极海冰、海洋和气候深入研究的基础上，重点研究极地涡旋罗斯贝波的核心作用，以及罗斯贝波变异的物理过程，深入研究北极变化对我国气候影响的主要渠道、关键过程和理。关键词：北极放大；海洋强迫；海冰；气候变化；气—冰—海相互作用

来源出版物：地球科学进展, 2015, 30(9): 985-995

联系邮箱：赵进平，jpzhao@ouc.edu.cn

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

何金海，武丰民，祁莉

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2 m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。

关键词：秋季北极海冰；冬季欧亚低温；年代际；年际

来源出版物：地球物理学报, 2015, 58(4): 1089-1102

联系邮箱：武丰民，wfm_nuist@163.com

北极海冰的年代际转型与中国冻雨年代际变化的关系

牛璐，黄菲，周晓

摘要：基于1961—2013年HadISST海冰密集度资料，定义了北极海冰的季节性融冰指数，结果显示近几十年来北极季节性融冰范围呈显著的上升趋势，并分别在20世纪70年代末和90年代中期存在显著的年代际转型，相应地，中国冻雨发生频数总体上呈现出显著的减少趋势，但也存在显著的年代际转型。在20世纪70年代末之前，北极季节性融冰范围较小但显著增长，中国冻雨频数年际变化振幅较大，且主要受巴伦支海、喀拉海海冰的影响；20世纪70年代末至90年代中期北极季节性融冰范围维持振荡特征，没有显著的线性趋势，中国冻雨频数变化振幅减小，与北极海冰相关较弱，主要相关因子为北大西洋及北太平洋海表温度变化；而90年代中期以后，北极海冰融化加快，特别是2007年以后，季节性融冰范围大大增加，而中国冻雨频数处于低发时段，其变化与太平洋扇区海冰及堪察加半岛附近海温呈显著负相关，季节性融冰的显著区域也从东西伯利亚海逆时针旋转向波弗特海-加拿大群岛北部扩张，同时向北极中央区扩张。不同年代影响冻雨的海温或海冰关键海区不同，产生特定的大气环流异常响应，进而影响到我国冻雨。

关键词：冻雨；季节性融冰；年代际转型；大气环流异常；海温

来源出版物：海洋学报, 2015, 37(11): 105-117

联系邮箱：黄菲，huangf@mail.ouc.edu.cn

中部型El Nino与北极海冰变化的联系

左涛，陈锦年，王凡

摘要：采用统计方法，分析了热带太平洋SSTA与北极海冰之间的联系。结果表明：北极海冰从20世纪80年代初由正距平转换为负距平，以-1.5%速率/10 a快速消融。尽管冬季海冰也出现减少趋势，但最大海冰减少出现在夏秋季，9月为1年中海冰减少最快的月份。相关分析发现，北极海冰的快速减少与热带太平洋海温变化存在密切联系，赤道中西部SSTA与北极海冰的关系更明显。Nino 4区域SSTA变化与北极海冰存在时滞3 a左右的最佳相关，6—10月SSTA对北极海冰影响最显著。通过分析，初步认为Nino4区域SSTA主要通过影响北半球中纬度气压场和经向环流场，进而影响AO变化，最终对北极海冰产生影响。

关键词：北极海冰密集度；快速消融；中部型El Nino；AO

来源出版物：海洋湖沼通报, 2015(3): 1-13

北半球夏季中高纬度大气阻塞对北极海冰变化的影响

肖贻青，黄斌，刁一娜

摘要：利用NCEP/NCAR再分析逐日500 hPa高度场资料，对北半球夏季中高纬度大气阻塞特征进行统计分析，发现大气阻塞活动频率高的地区主要集中在白令海峡区域、鄂霍次克海区域、欧亚大陆区域及格陵兰区域。而通过NSIDC提供的卫星观测资料发现近30年夏季海冰容易减少的区域正好对应阻塞活动北部的高纬度地区。分别通过对以上4个区域有阻塞发生相对没有阻塞发生时的500 hPa位势高度场、地面温度场、850 hPa经向瞬变热通量输送和平流输送等异常变化场进行对比分析，结果发现夏季中高纬度阻塞频率的增加对海冰的减少有显著影响，主要体现在阻塞的发生发展可通过增加高纬度地面温度、对极地的热量输送和暖平流输送来加快海冰的融化。这种阻塞引起的热力作用在鄂霍次克海和欧亚大陆区域效果更为显著。

关键词：北极海冰；北极增暖；阻塞

来源出版物：极地研究, 2015, 27(4): 364-378

联系邮箱：肖贻青，xxyyqq1222@163.com

累积海冰密集度及其在认识北极海冰快速变化的作用

王维波，赵进平

摘要：为定量分析北冰洋海冰密集度年际差异，提出并采用累积海冰密集度（ASIC）概念。利用SSMR/SSMI的分辨率为25 km的海冰密集度数据，分别研究了1979—2011年北极海冰在融冰期（4—9月）和结冰期（10月至翌年3月）的变化过程以及2个冰期内ASIC的区域差异。研究发现，在1979—1989年、1989—1999年和1999—2009年期间，融冰期海冰发生明显变化的范围都远远大于结冰期海冰发生明显变化的范围。1998—2010年，融冰期内发生加速融化的海区并没有都出现结冰期冰量减小的现象。在此期间融冰期ASIC减小，结冰期ASIC也减小的海域仅集中在楚克奇海、新地岛北部海域以及格陵兰岛东西海岸。融冰期ASIC减小，而结冰期ASIC无明显变化的海域包括波弗特海、东西伯利亚海、拉普捷夫海和喀拉海。这些区域与局地陆地径流侵入的海域重合。研究发现，在这些区域，融冰期ASIC减少是陆地径流增大加速海冰融化引起的。在结冰期，陆地径流加速海水结冰的作用消除融冰期海水吸收大量太阳辐射能后发生推迟结冰的现象，使得ASIC无明显变化。融冰期ASIC减小，而结冰期ASIC增大的区域只有白令海。研究结果证明累积海冰密集度能够去除海冰高频变化而只表现低频变化，能够描述海冰的年际变化特征。同时由于海冰变化与海洋中其他物理参数存在显著关系，变T的ASIC可以更加方便地描述次表层叶绿素最大值层深度的变化。

关键词：海冰变化；陆地径流；北冰洋

来源出版物：地球科学进展, 2014, 29(6): 713-722

联系邮箱：王维波，wbwang@live.com

北极海冰消融及其对欧亚冬季低温影响的研究进展

武丰民，何金海，祁莉

摘要：21世纪以来北极气候系统正在发生着剧烈变化。北极海冰史无前例的急剧消融是其中最重要的指示和衡量标志。北极海冰的急剧消融与北极气温升高紧密联系，在近年来欧亚大陆频发的冬季低温事件中也扮演着关键角色。首先介绍了北极海冰的季节特征及近年来的消融现状，并从动力学和热力学2个方面总结了海冰急剧消融的可能原因。阐述了北极增温的季节特点及其与北极海冰消融的关系。分析了北极海冰消融与欧亚大陆冷冬频发的联系及其可能机理。基于对以上研究进展的总结，提出了该研究领域尚需解决的几个问题，为相关研究提供参考。

关键词：北极增幅；大气环流异常；欧亚冷冬

来源出版物：地球科学进展, 2014, 29(8): 913-921

联系邮箱：何金海，hejhnew@nuist.edu.cn

秋季北极海冰对中国冬季气温的影响

谢永坤，刘玉芝，黄建平

摘要：利用海冰资料、中国地面气候资料、环流特征量资料及NCEP/NCAR再分析资料，研究了秋季北极海冰变化对中国冬季平均气温、日气温变率以及异常低温天气的影响。分析结果表明，秋季北极海冰异常偏多年中国冬季常为暖冬；异常偏少年中国冬季常为冷冬，且异常低温天气出现频率更高，常发生低温灾害事件。秋季北极海冰通过影响后期的北半球极涡、东亚冬季风和西伯利亚高压进而影响中国冬季的平均气温，且通过影响冬季异常强西伯利亚高压的出现频次，影响中国冬季异常低温天气的发生频次。合成分析结果表明，秋季北极海冰异常偏少年的冬季，中国以北亚欧大陆高纬度的偏北风较强，且中国及其以北的中高纬度地区空气异常偏冷，导致极地和高纬度的冷空气易向南爆发,造成中国冬季气温偏低，异常低温天气频发。

关键词：北极海冰；冬季气温；日气温变率；异常低温天气

来源出版物：气象学报, 2014, 72(4): 703-710

中国近50年寒潮冷空气的时空特征及其与北极海冰的关系

朱晨玉，黄菲，石运昊，等

摘要：利用中国具有较长时间序列的527个站点1961—2010年的日平均温度观测资料，美国国家环境预报中心和国家大气研究中心（NCEP/NCAR）再分析资料以及伊利莱诺斯大学的海冰密集度资料，分析了我国近50年来寒潮的时空变化及与其相联系的海冰和大气环流异常的关系。结果表明，中国寒潮冷空气活动频数存在两个主要模态，第一模态表现在中国北方冷空气活动频数呈年代际减少趋势，1980年之前寒潮冷空气频数偏多，1990年后寒潮冷空气频数偏少；第二模态表现为我国南方冷空气频数的年际振荡特征。第一模态寒潮冷空气频数的减少主要与全球变暖有关，北极海冰的减少使得1980年代后期北极涛动加强，并激发出欧亚遥相关波列进而影响我国的寒潮冷空气活动。第二模态则与近些年来夏季北极海冰的快速融化以及北极大气出现偶极子型环流异常有关，通过激发跨极型和类欧亚遥相关波列影响到后冬的中国南方寒潮冷空气活动增多。

关键词：寒潮；海冰；全球变暖；AO；EU；遥相关型；偶极子异常

来源出版物：中国海洋大学学报（自然科学版）, 2014, 44(12): 12-20

联系邮箱：黄菲，Huangf@ouc.edu.cn

北半球冰盖融化与北半球低温暴雪的相关性

杨冬红，杨学祥

摘要：2006—2013年北半球频遭低温暴雪袭击。引力模型的计算结果表明：北极冰盖大量融化导致北极地区海平面和大气等位面的大幅度下降，压力变化迫使北极地区冷水和冷空气流向北半球中低纬度地区。太平洋海温下降导致全球变暖停止。极地冰盖融化后全球海平面都将上升，这是一个错误的观点。最新模型研究表明，如果格林兰冰盖融化可导致其附近海平面将下降100 m，北苏格兰的海平面将下降3 m，冰岛周围海平面将下降10 m，南美部分地区海平面将上升10 m。冰盖融化导致地表巨量物质转移，改变了地球内外重力场，地球内核南移100 m，北极和南极海平面分别下降和上升7 cm。在海平面附近，大气等位面的变化幅度与海平面变化幅度非常接近。近期北极海冰和冰盖的融化只是最新模型的一个缩影。北极大量冷水和冷空气在下降等位面的压力下流过北半球中低纬度地区，导致北半球频遭低温暴雪袭击。在“全球变暖间断”现象持续了长达16 a之后，科学家正全力探究“全球变暖间断”现象背后的深层次原因.最新研究指出，1997—1998年赤道太平洋进入一个持续很久的低温状态，抑制了全球变暖的速度。海水温度的波动被称作拉马德雷现象（PDO），这种现象是解开“间断”谜团的关键。

关键词：冰盖；海平面；潮汐；地震；低温

来源出版物：地球物理学进展, 2014, 29(2): 610-615

北冰洋中心区海冰漂流与大气过程

卞林根，王继志，孙玉龙，等

摘要：利用北冰洋中心区漂流自动气象站（DAWS）2012 年9月—2013年2月的观测数据，分析了北极点周围海冰漂流轨迹和速度及相关大气过程。结果显示，北冰洋中心区海冰具有不稳定漂流过程。2012年9月1日—2013年1月6日，DAWS所在海冰从西向西北方向漂流，2013年1 月6日以后稳定地向东南方向漂流，平均移速为0.06 m/s，最大达到0.4 m/s。海冰漂流方向的突变和加速与穿极气旋和急流的影响有关。净辐射常出现短期突变过程，导致海冰从大气吸收能量，减缓了海冰的辐射冷却。爆发性增温过程的最大幅度达到30℃，是由强穿极气旋和伴随的暖湿气流向北极中心区输送引起，这种现象在中低纬度十分罕见。增温过程的作用是高空大气向冰面输送热量，导致海冰破裂，海冰硬度的脆变，减缓海冰厚度的增长，这种过程可能是北极海冰面积和厚度减少重要过程。

关键词：北冰洋；漂流自动气象站；海冰运动；爆发性增温；穿极气旋

来源出版物：海洋学报（中文版）, 2014, 36(10): 48-55

Effects of arctic sea ice decline on weather and climate: A review

Timo Vihma

Abstract: The areal extent, concentration and thickness of sea ice in the Arctic Ocean and adjacent seas have strongly decreased during the recent decades, but cold, snow-rich winters have been common over mid-latitude land areas since 2005. A review is presented on studies addressing the local and remote effects of the sea ice decline on weather and climate. It is evident that the reduction in sea ice cover has increased the heat flux from the ocean to atmosphere in autumn and early winter. This has locally increased air temperature, moisture, and cloud cover and reduced the static stability in the lower troposphere. Several studies based on observations, atmospheric reanalyses, and model experiments suggest that the sea ice decline, together with increased snow cover in Eurasia, favours circulation patterns resembling the negative phase of the North Atlantic Oscillation and Arctic Oscillation. The suggested largescale pressure patterns include a high over Eurasia, which favours cold winters in Europe and northeastern Eurasia. A high over the western and a low over the eastern North America have also been suggested, favouring advection of Arctic air masses to North America. Mid-latitude winter weather is, however, affected by several other factors, which generate a large inter-annual variability and often mask the effects of sea ice decline. In addition, the small sample of years with a large sea ice loss makes it difficult to distinguish the effects directly attributable to sea ice conditions. Several studies suggest that, with advancing global warming, cold winters in mid-latitude continents will no longer be common during the second half of the twenty-first century. Recent studies have also suggested causal links between the sea ice decline and summer precipitation in Europe, the Mediterranean, and East Asia.

Keywords: arctic; climate change; mid-latitude weather; sea ice; snow; winter weather

来源出版物：Surv Geophys, 2014, 35: 1175-1214

Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: A review

R. Döscher; T. Vihma; E. Maksimovich

Abstract: Sea ice is the central component and most sensitive indicator of the Arctic climate system. Both the depletion and areal decline of the Arctic sea ice cover, observed since the 1970s, have accelerated since the millennium. While the relationship of global warming to sea ice reduction is evident and underpinned statistically, it is the connecting mechanisms that are explored in detail in this review. Sea ice erodes both from the top and the bottom. Atmospheric, oceanic and sea ice processes interact in nonlinear ways on various scales. Feedback mechanisms lead to an Arctic amplification of the global warming system: the amplification is both supported by the ice depletion and, at the same time, accelerates ice reduction. Knowledge of the mechanisms of sea ice decline grew during the 1990s and deepened when the acceleration became clear in the early 2000s. Record minimum summer sea ice extents in 2002, 2005, 2007 and 2012 provide additional information on the mechanisms. This article reviews recent progress in understanding the sea ice decline. Processes are revisited from atmospheric, oceanic and sea ice perspectives. There is strong evidence that decisive atmospheric changes are the major driver of sea ice change. Feedbacks due to reduced ice concentration, surface albedo, and ice thickness allow for additional local atmospheric and oceanic influences and self-supporting feedbacks. Large-scale ocean influences on Arctic Ocean hydrology and circulation are highly evident. Northward heat fluxes in the ocean are clearly impacting the ice margins, especially in the Atlantic sector of the Arctic. There is little indication of a direct and decisive influence of the warming ocean on the overall sea ice cover, due to an isolating layer of cold and fresh water underneath the sea ice.

来源出版物：Atmospheric Chemistry and Physics, 2014, 14: 13571–13600

Role of Arctic sea ice in global atmospheric circulation: A review

Dagmar Budikova

Abstract: Formed by the freezing of sea water, sea ice defines the character of the marine Arctic. The principal purpose of this review is to synthesize the published efforts that document the potential impact of Arctic sea ice on remote climates. The emphasis is on atmospheric processes and the resulting modifications in surface conditions such as air temperature, precipitation patterns, and storm track behavior at interannual timescales across the middle and low latitudes of the Northern hemisphere during cool months. Addressed also are the theoretical, methodological, and logistical challenges facing the current observational and modeling studies that aim to improve our awareness of the role that Arctic sea ice plays in the definition of global climate. Moving towards an improved understanding of the role that polar sea ice plays in shaping the global climate is a subject of timely importance as the Arctic environment is currently undergoing rapid change with little slowing down forecasted for the future.

来源出版物：Global and Planetary Change, 2009, 68: 149–163

Winter weather patterns over northern eurasia and arctic sea ice loss

Bingyi Wu; Dörthe Handorf; Klaus Dethloff; et al.

Abstract: Using the NCEP/NCAR and Japanese(JRA-25) re-analysis winter daily(Dec. 1 to Feb. 28) data for the period 1979 to 2012, this paper reveals the leading pattern of winter daily 850 hPa wind variability over northern Eurasia from a dynamic perspective. The results show that the leading pattern accounts for 18% of the total anomalous kinetic energy and consists of two sub-patterns: the dipole and the tripole wind patterns. The dipole wind pattern does not exhibit any apparent trend. The tripole wind pattern, however, has displayed significant trends since the late 1980s. The negative phase of the tripole wind pattern corresponds to an anomalous anticyclone over northern Eurasia during winter, as well as two anomalous cyclones respectively occurring over southern Europe and in the mid-high latitudes of East Asia. These anomalous cyclones in turn lead to enhanced winter precipitation in these two regions, as well as negative surface temperature anomalies over the mid-high latitudes of Asia. The intensity of the tripole wind pattern and the frequency of its extreme negative phase are significantly correlated with autumn Arctic sea ice anomalies. Simulation experiments further demonstrate that the winter atmospheric response to Arctic sea ice decrease is dynamically consistent with the observed trend in the tripole wind pattern over the past 24 winters, which is one of causes of the observed wintersurface air temperature decline trend over Central and East Asia. The results of this study also imply that East Asia may experience more frequent and/or intense winter extreme weather events in association with the loss of Arctic sea ice.

Keywords: extreme weather event; tripole wind pattern; autumn sea ice decline; cold winter

来源出版物：Monthly Weather Review, 2013, 141: 3786-3800

On the relationship between winter sea ice and summer atmospheric circulation over eurasia

Bingyi Wu; Renhe Zhang; Rosanne D’Arrigo; et al.

Abstract: Using the NCEP/NCAR and JRA-25 re-analysis data, this paper investigates the association between winter sea ice concentration(SIC) in Baffin Bay southward to the eastern coast of Newfoundland, and the ensuing summer atmospheric circulation over the mid-high latitudes of Eurasia. It is found that winter SIC anomalies are significantly correlated with the ensuing summer 500 hPa height anomalies that dynamically correspond to the Eurasian pattern of 850 hPa wind variability and significantly influence summer rainfall variability over northern Eurasia. Spring atmospheric circulation anomalies south of Newfoundland, associated with persistent winter-spring SIC and a horseshoe-like pattern of sea surface temperature(SST) anomalies in the North Atlantic, act as a bridge linking winter SIC and the ensuing summer atmospheric circulation anomalies over northern Eurasia. Indeed, this study only reveals the association based on observations and simple simulation experiments with SIC forcing. The more precise mechanism for this linkage needs to be addressed in future work using numerical simulations with SIC and SST as the external forcings. Our results have the following implication: Winter SIC west of Greenland is a possible precursor for summer atmospheric circulation and rainfall anomalies over northern Eurasia.

来源出版物：Journal of Climate, 2013, 26: 5523-5536

Fast atmospheric response to a sudden thinning of Arctic sea ice

Semmler, Tido; Jung, Thomas; Serrar, Soumia

Abstract: In order to understand the influence of a thinner Arctic sea ice on the wintertime atmosphere, idealized ensemble experiments with increased sea ice surface temperature have been carried out with the Integrated Forecast System of the European Centre for Medium-Range Weather Forecasts. The focus is on the fast atmospheric response to a sudden “thinning” of Arctic sea ice to disentangle the role of various different processes. We found that boundary layer turbulence is the most important process that distributes anomalous heat vertically. Anomalous longwave radiation plays an important role within the first few days before temperatures in the lower troposphere had time to adjust. The dynamic response tends to balance that due to boundary layer turbulence while cloud processes and convection play only a minor role. Overall the response of the atmospheric large-scale circulation is relatively small with up to 2 hPa in the mean sea level pressure during the first 15 days; the quasiequilibrium response reached in the second and third month of the integration is about twice as large. During the first few days the response tends to be baroclinic in the whole Arctic. Already after a few days an anti-cyclonic equivalent-barotropic response develops over north-western Siberia and north-eastern Europe. The structure resembles very much that of the atmospheric equilibrium response indicating that fast tropospheric processes such as fewer quasi-barotropic cyclones entering this continental area are key opposed to slower processes such as those involving, for example, stratosphere-troposphere interaction.

Keywords: Arctic sea ice; Arctic boundary layer; atmospheric circulation; numerical modelling

来源出版物：Climate Dynamics, 2016, 46(3-4): 1015-1025

Investigation of the atmospheric mechanisms related to the autumn sea ice and winter circulation link in the Northern Hemisphere

King, Martin P; Hell, Momme; Keenlyside, Noel

Keywords: The relationship of Barents-Kara sea ice concentration in October and November with atmospheric circulation in the subsequent winter is examined using reanalysis and observational data. The analyses are performed on data with the 5-year running means removed to reduce the potential effects of slowly-varying external driving factors, such as global warming. We show that positive(negative) Barents-Kara sea ice concentration anomaly in autumn is associated with a positive(negative) North Atlantic Oscillation-like(NAO) pattern with lags of up to 3 months. The month-to-month variations in the lag relationships of the atmospheric anomalies related toNovember sea ice concentration are presented. Further analysis shows that the stratosphere-troposphere interaction may provide the memory in the system: positive(negative) sea ice concentration anomaly in November is associated with a strengthened(weakened) stratospheric polar vortex and these anomalies propagate downward leading to the positive(negative) NAO-like pattern in the late December to early January. This stratosphere mechanism may also play a role for Barents-Kara sea ice anomaly in December, but not for September and October. Consistently, Eliassen-Palm, eddy heat and momentum fluxes suggest that there is strong forcing of the zonal winds in November.

Keywords: climate impact of arctic sea ice; sea ice-atmosphere interaction; North Atlantic Oscillation; stratosphere downward propagation

来源出版物：Climate Dynamics, 2016, 46(3-4): 1185-1195

The effect of downwelling longwave and shortwave radiation on arctic summer sea ice

Kapsch, Marie-Luise; Graversen, Rune Grand; Tjernstrom, Michael; et al.

Abstract: The Arctic summer sea ice has diminished fast in recent decades. A strong year-to-year variability on top of this trend indicates that sea ice is sensitive to short-term climate fluctuations. Previous studies show that anomalous atmospheric conditions over the Arctic during spring and summer affect ice melt and the September sea ice extent(SIE). These conditions are characterized by clouds, humidity, and heat anomalies that all affect downwelling shortwave(SWD) and longwave(LWD) radiation to the surface. In general, positive LWD anomalies are associated with cloudy and humid conditions, whereas positive anomalies of SWD appear under clear-sky conditions. Here the effect of realistic anomalies of LWD and SWD on summer sea ice is investigated by performing experiments with the Community Earth System Model. The SWD and LWD anomalies are studied separately and in combination for different seasons. It is found that positive LWD anomalies in spring and early summer have significant impact on the September SIE, whereas winter anomalies show only little effect. Positive anomalies in spring and early summer initiate an earlier melt onset, hereby triggering several feedback mechanisms that amplify melt during the succeeding months. Realistic positive SWD anomalies appear only important if they occur after the melt has started and the albedo is significantly reduced relative to winter conditions. Simulations where both positive LWD and negative SWD anomalies are implemented simultaneously, mimicking cloudy conditions, reveal that clouds during spring have a significant impact on summer sea ice while summer clouds have almost no effect.

Keywords: geographic location; entity; Arctic; sea ice; circulation; dynamics; clouds; physical meteorology and climatology; feedback; surface fluxes; models and modeling; climate models

来源出版物：Journal of Climate, 2016, 29(3): 1143-1159

Influence of sea ice on Arctic precipitation

Kopec, Ben G; Feng, Xiahong; Michel, Fred A; et al.

Abstract: Global climate is influenced by the Arctic hydrologic cycle, which is, in part, regulated by sea ice through its control on evaporation and precipitation. However, the quantitative link between precipitation and sea ice extent is poorly constrained. Here we present observational evidence for the response of precipitation to sea ice reduction and assess the sensitivity of the response. Changes in the proportion of moisture sourced from the Arctic with sea ice change in the Canadian Arctic and Greenland Sea regions over the past two decades are inferred from annually averaged deuterium excess(d-excess) measurements from six sites. Other influences on the Arctic hydrologic cycle, such as the strength of meridional transport, are assessed using the North Atlantic Oscillation index. We find that the independent, direct effect of sea ice on the increase of the percentage of Arctic sourced moisture(or Arctic moisture proportion, AMP) is 18.2± 4.6% and 10.8±3.6%/100000 km2sea ice lost for each region, respectively, corresponding to increases of 10.9± 2.8% and 2.7±1.1% 1 degrees C of warming in the vapor source regions. The moisture source changes likely result in increases of precipitation and changes in energy balance, creating significant uncertainty for climate predictions.

Keywords: water cycle; precipitation; sea ice; climate change; deuterium excess

来源出版物：Proceedings of the National Academy of Sciences of the United States of America, 2016, 113(1): 46-51

Arctic sea ice and warm season North American extreme surface air temperatures

Budikova, Dagmar; Chechi, Leonardo

Abstract: A growing amount of evidence points to anotable linkage between the changing Arctic cryosphere and weather in the middle latitudes of the Northern Hemisphere. Recent studies propose a series of mechanisms that make plausible the connection between Arctic amplification/sea ice decline and extreme weather. Using composite analyses, this study examines associations between the frequency of occurrence of boreal summer daily extreme surface air temperatures across North America and simultaneous mean Arctic sea ice concentration(SIC) conditions during the period 1979-2013. Four distinct regions show coherent relationships including large sections of the eastern USA, Canada and the Canadian Arctic, central North America, southeast USA, and the west coast from southern Canada to Alaska. Across the eastern USA and Canada, as well as in western North America, the connections are principally shaped by low ice conditions with an expected decline in the incidence of cool nights/days and an increase in the incidence of warm nights/days. The ice-temperature relationships observed in the other regions are mostly shaped by high ice conditions. Synoptic analyses indicate the associations to be reflected in mean summer surface air temperature(SAT) and surface anomaly flows, as well as in the 500 and 200 hPa geopotential height flow and mean zonal wind anomaly patterns. Areas with the greatest atmospheric flow modifications have been generally associated with regions that display most notable extreme temperature frequency modifications.

Keywords: Arctic ice; summer extreme temperature; North America

来源出版物：Climate Research, 2016, 67(1): 15-29

Evidence for a wavier jet stream in response to rapid Arctic warming

Francis, Jennifer A; Vavrus, Stephen J

Abstract: New metrics and evidence are presented that support a linkage between rapid Arctic warming, relative to Northern hemisphere mid-latitudes, and more frequent high-amplitude(wavy) jet-stream configurations that favor persistent weather patterns. We find robust relationships among seasonal and regional patterns of weaker poleward thickness gradients, weaker zonal upper-level winds, and a more meridional flow direction. These results suggest that as the Arctic continues to warm faster than elsewhere in response to rising greenhouse-gas concentrations, the frequency of extreme weather events caused by persistent jet-stream patterns will increase.

Keywords: jet stream; Arctic amplification; extreme weather

来源出版物：Environmental Research Letters, 2015, 10(1): 014005

Arctic sea ice thickness loss determined using subsurface, aircraft, and satellite observations

Lindsay, R; Schweiger, A

Abstract: Sea ice thickness is a fundamental climate state variable that provides an integrated measure of changes in the high-latitude energy balance. However, observations of mean ice thickness have been sparse in time and space, making the construction of observation-based time series difficult. Moreover, different groups use a variety of methods and processing procedures to measure ice thickness, and each observational source likely has different and poorly characterized measurement and sampling errors. Observational sources used in this study include upward-looking sonars mounted on submarines or moorings, electromagnetic sensors on helicopters or aircraft, and lidar or radar altimeters on airplanes or satellites. Here we use a curve-fitting approach to determine the large-scale spatial and temporal variability of the ice thickness as well as the mean differences between the observation systems, using over 3000 estimates of the ice thickness. The thickness estimates are measured over spatial scales of approximately 50 km or time scales of 1 month, and the primary time period analyzed is 2000-2012 when the modern mix of observations is available. Good agreement is found between five of the systems, within 0.15 m, while systematic differences of up to 0.5 m are found for three others compared to the five. The trend in annual mean ice thickness over the Arctic Basin is -0.58± 0.07 m decade-1over the period 2000-2012. Applying our method to the period 1975-2012 for the central Arctic Basin where we have sufficient data(the SCICEX box), we find that the annual mean ice thickness has decreased from 3.59 m in 1975 to 1.25 m in 2012, a 65% reduction. This is nearly double the 36% decline reported by an earlier study. These results provide additional direct observational evidence of substantial sea ice losses found in model analyses.

来源出版物：Cryosphere, 2015, 9(1): 269-283

The role of ocean-atmosphere coupling in the zonal-mean atmospheric response to arctic sea ice loss

Deser, Clara; Tomas, Robert A; Sun, Lantao

Abstract: The role of ocean-atmosphere coupling in thezonal-mean climate response to projected late twentyfirst-century Arctic sea ice loss is investigated using Community Climate System Model version 4(CCSM4) at 1° spatial resolution. Parallel experiments with different ocean model configurations(full-depth, slab, and no interactive ocean) allow the roles of dynamical and thermodynamic ocean feedbacks to be isolated. In the absence of ocean coupling, the atmospheric response to Arctic sea ice loss is confined to north of 30°N, consisting of a weakening and equatorward shift of the westerlies accompanied by lower tropospheric warming and enhanced precipitation at high latitudes. With ocean feedbacks, the response expands to cover the whole globe and exhibits a high degree of equatorial symmetry: The entire troposphere warms, the global hydrological cycle strengthens, and the intertropical convergence zones shift equatorward. Ocean dynamics are fundamental to producing this equatorially symmetric pattern of response to Arctic sea ice loss. Finally, the absence of a poleward shift of the wintertime Northern Hemisphere westerlies in CCSM4’s response to greenhouse gas radiative forcing is shown to result from the competing effects of Arctic sea ice loss and greenhouse warming on the meridional temperature gradient in middle latitudes.

来源出版物：Journal of Climate, 2015, 28(6): 2168-2186

Effects of arctic sea ice decline on weather and climate: A review

Vihma, Timo

Abstract: The areal extent, concentration and thickness of sea ice in the Arctic Ocean and adjacent seas have strongly decreased during the recent decades, but cold, snow-rich winters have been common over mid-latitude land areas since 2005. A review is presented on studies addressing the local and remote effects of the sea ice decline on weather and climate. It is evident that the reduction in sea ice cover has increased the heat flux from the ocean to atmosphere in autumn and early winter. This has locally increased air temperature, moisture, and cloud cover and reduced the static stability in the lower troposphere. Several studies based on observations, atmospheric reanalyses, and model experiments suggest that the sea ice decline, together with increased snow cover in Eurasia, favours circulation patterns resembling the negative phase of the North Atlantic Oscillation and Arctic Oscillation. The suggested large-scale pressure patterns include a high over Eurasia, which favours cold winters in Europe and northeastern Eurasia. A high over the western and a low over the eastern North America have also been suggested, favouring advection of Arctic air masses to North America. Mid-latitude winter weather is, however, affected by several other factors, which generate a large inter-annual variability and often mask the effects of sea ice decline. In addition, the small sample of years with a large sea ice loss makes it difficult to distinguish the effects directly attributable to sea ice conditions. Several studies suggest that, with advancing global warming, cold winters in mid-latitude continents will no longer be common during the second half of the twenty-first century. Recent studies have also suggested causal links between the sea ice decline and summer precipitation in Europe, the Mediterranean, and East Asia

Keywords: arctic; climate change; mid-latitude weather; sea ice; snow; winter weather

来源出版物：Surveys in Geophysics, 2014, 35(5): 1175-1214

Robust Arctic sea-ice influence on the frequent Eurasian cold winters in past decades

Mori, Masato; Watanabe, Masahiro; Shiogama, Hideo; et al.

Abstract: Over the past decade, severe winters occurred frequently in mid-latitude Eurasia, despite increasing global and annual-mean surface air temperatures. Observations suggest that these cold Eurasian winters could have been instigated by Arctic sea-ice decline, through excitation of circulation anomalies similar to the Arctic Oscillation. In climate simulations, however, a robust atmospheric response to sea-ice decline has not been found, perhaps owing to energetic internal fluctuations in the atmospheric circulation. Here we use a 100-member ensemble of simulations with an atmospheric general circulation model driven by observation-based sea-ice concentration anomalies to show that as a result of sea-ice reduction in the Barents-Kara Sea, the probability of severe winters has more than doubled in central Eurasia. In our simulations, the atmospheric response to sea-ice decline is approximately independent of the Arctic Oscillation. Both reanalysis data and our simulations suggest that sea-ice decline leads to more frequent Eurasian blocking situations, which in turn favour cold-air advection to Eurasia and hence severe winters. Based on a further analysis ofsimulations from 22 climate models we conclude that the sea-ice-driven cold winters are unlikely to dominate in a warming future climate, although uncertainty remains, due in part to an insufficient ensemble size.

来源出版物：Nature Geoscience, 2014, 7(12): 869-873

Atmospheric impacts of Arctic sea-ice loss, 1979-2009: Separating forced change from atmospheric internal variability

Screen, James A; Deser, Clara; Simmonds, Ian; et al.

Abstract: The ongoing loss of Arctic sea-ice cover has implications for the wider climate system. The detection and importance of the atmospheric impacts of sea-ice loss depends, in part, on the relative magnitudes of the sea-ice forced change compared to natural atmospheric internal variability(AIV). This study analyses large ensembles of two independent atmospheric general circulation models in order to separate the forced response to historical Arctic sea-ice loss(1979-2009) from AIV, and to quantify signal-to-noise ratios. We also present results from a simulation with the sea-ice forcing roughly doubled in magnitude. In proximity to regions of sea-ice loss, we identify statistically significant near-surface atmospheric warming and precipitation increases, in autumn and winter in both models. In winter, both models exhibit a significant lowering of sea level pressure and geopotential height over the Arctic. All of these responses are broadly similar, but strengthened and/or more geographically extensive, when the sea-ice forcing is doubled in magnitude. Signal-tonoise ratios differ considerably between variables and locations. The temperature and precipitation responses are significantly easier to detect(higher signal-to-noise ratio) than the sea level pressure or geopotential height responses. Equally, the local response(i.e., in the vicinity of sea-ice loss) is easier to detect than the mid-latitude or upper-level responses. Based on our estimates of signal-to-noise, we conjecture that the local near-surface temperature and precipitation responses to past Arctic sea-ice loss exceed AIV and are detectable in observed records, but that the potential atmospheric circulation, upper-level and remote responses may be partially or wholly masked by AIV.

Keywords: Arctic sea ice; atmospheric modelling; ensembles; detection and attribution; internal variability; signal-to-noise ratio

来源出版物：Climate Dynamics, 2014, 43(1-2): 333-344

September Arctic sea-ice minimum predicted by spring melt-pond fraction

Schroeder, David; Feltham, Daniel L; Flocco, Daniela; et al.

Abstract: The area of Arctic September sea ice has diminished from about 7 million km2in the 1990s to less than 5 million km2in five of the past seven years, with a record minimum of 3.6 million km2in 2012. The strength of this decrease is greater than expected by the scientific community, the reasons for this are not fully understood, and its simulation is an on-going challenge for existing climate models. With growing Arctic marine activity there is an urgent demand for forecasting Arctic summer sea ice. Previous attempts at seasonal forecasts of ice extent were of limited skill. However, here we show that the Arctic sea-ice minimum can be accurately forecasted from melt-pond area in spring. We find a strong correlation between the spring pond fraction and September sea-ice extent. This is explained by a positive feedback mechanism: more ponds reduce the albedo; a lower albedo causes more melting; more melting increases pond fraction. Our results help explain the acceleration of Arctic sea-ice decrease during the past decade. The inclusion of our new melt-pond model promises to improve the skill of future forecast and climate models in Arctic regions and beyond

来源出版物：Nature Climate Change, 2014, 4(5): 353-357

On the 2012 record low Arctic sea ice cover: Combined impact of preconditioning and an August storm

Parkinson, Claire L; Comiso, Josefino C

Abstract: A new record low Arctic sea ice extent for the satellite era, 3.4×106km2, was reached on 13 September 2012; and a new record low sea ice area, 3.0×106km2, was reached on the same date. Preconditioning through decades of overall ice reductions made the ice pack more vulnerable to a strong storm that entered the central Arctic in early August 2012. The storm caused the separation of an expanse of 0.4×106km2of ice that melted in total, while its removal left the main pack more exposed to wind and waves, facilitating the main pack’s further decay. Future summer storms could lead to a further acceleration of the decline in the Arctic sea ice cover and should be carefully monitored.

来源出版物：Geophysical Research Letters, 2013, 40(7): 1356-1361

The atmospheric response to three decades of observed arctic sea ice loss

Screen, James A; Simmonds, Ian; Deser, Clara; et al.

Abstract: Arctic sea ice is declining at an increasing rate with potentially important repercussions. To understand better the atmospheric changes that may have occurred in response to Arctic sea ice loss, this study presents results from atmospheric general circulation model(AGCM) experiments in which the only time-varying forcings prescribed were observed variations in Arctic sea ice and accompanying changes in Arctic sea surface temperatures from 1979 to 2009. Two independent AGCMs are utilized in order to assess the robustness of the response across different models. The results suggest that the atmospheric impacts of Arctic sea ice loss have been manifested most strongly within the maritime and coastal Arctic and in the lowermost atmosphere. Sea ice loss has driven increased energy transfer from the ocean to the atmosphere, enhanced warming and moistening of the lower troposphere, decreased the strength of the surface temperature inversion, and increased lower-tropospheric thickness; all of these changes are most pronounced in autumn and early winter(September-December). The early winter(November-December) atmospheric circulation response resembles the negative phase of the North Atlantic Oscillation(NAO); however, the NAO-type response is quite weak and is often masked by intrinsic(unforced) atmospheric variability. Some evidence of a late winter(March-April) polar stratospheric cooling response to sea ice loss is also found, which may have important implications for polar stratospheric ozone concentrations. The attribution and quantification of other aspects of the possible atmospheric response are hindered by model sensitivities and large intrinsic variability. The potential remote responses to Arctic sea ice change are currently hard to confirm and remain uncertain.

来源出版物：Journal of Climate, 2013, 26(4): 1230-1248

The impact of an intense summer cyclone on 2012 Arctic sea ice retreat

Zhang, Jinlun; Lindsay, Ron; Schweiger, Axel; et al.

Abstract: This model study examines the impact of an intense early August cyclone on the 2012 record low Arctic sea ice extent. The cyclone passed when Arctic sea ice was thin and the simulated Arctic ice volume had already declined similar to 40% from the 2007-2011 mean. The thin sea ice pack and the presence of ocean heat in the near surface temperature maximum layer created conditions that made the ice particularly vulnerable to storms. During the storm, ice volume decreased about twice as fast as usual, owing largely to a quadrupling in bottom melt caused by increased upward ocean heat transport. This increased ocean heat flux was due to enhanced mixing in the oceanic boundary layer, driven by strong winds and rapid ice movement. A comparison with a sensitivity simulation driven by reduced wind speeds during the cyclone indicates that cyclone-enhanced bottom melt strongly reduces ice extent for about 2 weeks, with a declining effect afterward. The simulated Arctic sea ice extent minimum in 2012 is reduced by the cyclone but only by 0.15×106km2(4.4%). Thus, without the storm, 2012 would still have produced a record minimum.

来源出版物：Geophysical Research Letters, 2013, 40(4): 720-726

编辑：卫夏雯

The role of sea ice and other fresh water in the Arctic circulation

Aagaard K; Carmack EC

Salinity stratification is critical to the vertical circulation of the high-latitude ocean. We here examine the control of the vertical circulation in the northern seas, and the potential for altering it, by considering the budgets and storage of fresh water in the Arctic Ocean and in the convective regions to the south. We find that the present-day Greenland and Iceland seas, and probably also the Labrador Sea, are rather delicately poised with respect to their ability to sustain convection. Small variations in the fresh water supplied to the convective gyres from the Arctic Ocean via the East Greenland Current can alter or stop the convection in what may be a modern analog to the halocline catastrophes proposed for the distant past. The North Atlantic salinity anomaly of the 1960s and 1970s is a recent example; it must have had its origin in an increased fresh water discharge from the Arctic Ocean. Similarly, the freshening and cooling of the deep North Atlantic in recent years is a likely manifestation of the increased transfer of fresh water from the Arctic Ocean into the convective gyres. Finally, we note that because of the temperature dependence of compressibility, a slight salinity stratification in the convective gyres is required to efficiently ventilate the deep ocean.

sea surface temperature; sea ice; night marine air temperature; climate data reconstruction; bias correction; climate change