Climatic and atmospheric teleconnection indices and western Arctic sea ice variability

This study examines the sea ice cover minima in the western Arctic in the context of several climatic mechanisms known to impact its variability. The September latitude of western Arctic sea ice is measured along 11 equally-spaced longitudes extending from 176º?W to 126º?W in the Chukchi and Beaufort Seas, 1953–2010. Indices of seasonal atmospheric and oceanic teleconnections and annual mean Northern Hemisphere temperatures (NHT) and CO₂ concentration are orthogonalized using rotated principal component analysis, forming predictors regressed onto the sea ice latitude data at each longitude using stepwise multiple linear regression. Prior to 1998, small amounts of September ice edge variance are explained by teleconnections such as the Arctic Dipole, Arctic Oscillation, and Pacific-North American Pattern. NHTs begin explaining large amounts of ice edge variance starting in 1998. For the 1953–2010 period, up to 68% of the ice edge variance is explained at 161°?W in the Chukchi Sea, mostly by NHTs. With the exception of the three easternmost longitudes (136–126°?W), the teleconnections and NHTs explain over 50% of the regional ice edge variance. Increases in both NHTs and ice retreat since the mid-1990s account for the large explained variances observed in regression analyses extending into recent years.     

南北极海冰变化及其影响因素的对比分析

海冰是海洋-大气交互系统的重要组成部分,与全球气候系统间存在灵敏的响应和反馈机制。本文选用欧洲空间局发布的1992—2008年海冰密集度数据分析了南北极海冰在时间和空间上的变化规律与趋势,并结合由美国环境预报中心(National Centers for Environmental Prediction,NCEP)和美国大气研究中心(National Center for Atmospheric Research, NCAR)联合制作的NCEP/NCAR气温数据和ENSO指数探讨了南北极海冰变化的影响因素。结果表明,北极海冰面积呈明显的减少趋势,其中夏季海冰最小月的减少更快。北冰洋中央海盆区、巴伦支海、喀拉海、巴芬湾和拉布拉多海的减少最明显。南极海冰面积呈微弱增加趋势,罗斯海、太平洋扇区和大西洋扇区的海冰增加。北极海冰面积与气温有显著的滞后1个月的负相关关系(P0.01)。北极升温显著,北冰洋中央海盆区、喀拉海、巴伦支海、巴芬湾和楚科奇海升温趋势最大,海冰减少很明显。南极在南大西洋、南太平洋呈降温趋势,海冰增加。北极海冰减少与39个月之后ONI的下降、40个月之后SOI的上升密切相关;南极海冰增加与7个月之后ONI的下降、6个月之后SOI的上升存在很好的响应关系。南北极海冰变化与三次ENSO的强暖与强冷事件有很好的对应关系。     

基于无人机观测的北极冰面融池及冰面粗糙度信息提取方法研究

北极冰面融池对于研究北极海冰质量平衡、海洋混合层热收支和盐量收支等具有重要意义。为了获得准确的融池覆盖率,本研究提出了一种利用无人机进行北极海冰融池及冰面粗糙度信息提取的方法。在第7次中国北极科学考察期间,利用无人机获取加拿大海盆周边浮冰区冰面航拍影像,针对海冰航拍图像特殊性改进了基于暗原色先验的图像去雾算法,对拼接后的航拍图像进行融池识别,计算得到航拍区域的融池覆盖率。同时利用航拍影像三维建模得到海冰表面相对高程和冰面粗糙度,继而对融池覆盖率和海冰表面粗糙度分布规律进行研究。结果表明,在本次航拍区域,海冰粗糙度大的区域具有更多小面积的融池,而融透的、面积大的融池多出现在粗糙度小的平整冰区。     

Investigation of Arctic and Antarctic spatial and depth patterns of sea water in CTD profiles using chemometric data analysis

In this paper we examine 2- and 3-way chemometric methods for analysis of Arctic and Antarctic water samples. Standard CTD (conductivity–temperature–depth) sensor devices were used during two oceanographic expeditions (July 2007 in the Arctic; February 2009 in the Antarctic) covering a total of 174 locations. The output from these devices can be arranged in a 3-way data structure (according to sea water depth, measured variables, and geographical location). We used and compared 2- and 3-way statistical tools including PCA, PARAFAC, PLS, and N-PLS for exploratory analysis, spatial patterns discovery and calibration. Particular importance was given to the correlation and possible prediction of fluorescence from other physical variables. MATLAB's mapping toolbox was used for geo-referencing and visualization of the results. We conclude that: 1) PCA and PARAFAC models were able to describe data in a satisfactory way, but PARAFAC results were easier to interpret; 2) applying a 2-way model to 3-way data raises the risk of flattening the covariance structure of the data and losing information; 3) the distinction between Arctic and Antarctic seas was revealed mostly by PC1, relating to the physico-chemical properties of the water samples; and 4) we confirm the ability to predict fluorescence values from physical measurements when the 3-way data structure is used in N-way PLS regression.     

2014年夏季北极东北航道冰情分析

使用2003—2014年6—9月份的AMSR-E和AMSR-2海冰密集度数据计算了北极海冰范围, 并获得海冰空间分布图。通过分析得出, 2014年北极夏季海冰范围在数值上与2003—2013年的多年平均值很接近, 在空间分布上与多年中值范围相比主要表现为两个方面的不同：(1)2014年夏季拉普捷夫海及其以北海域海冰明显少于多年中值范围, 9月份冰区最北边界超过了85°N;(2)巴伦支海北部斯瓦尔巴群岛至法兰士约瑟夫地群岛区域海冰范围明显多于多年中值范围, 而且海冰范围在8月份不减反增, 冰区边界较7月份往南扩张了约0.8个纬度。2014年夏季在拉普捷夫海以南风为主, 而在巴伦支海以北风为主。南风将俄罗斯大陆上温暖的空气吹向高纬地区, 造成高纬地区温度偏高, 促进拉普捷夫海海冰融化, 并使海冰往北退缩。北风将北冰洋上的冷空气吹向低纬地区, 造成巴伦支海的气温偏低, 不利于海冰的融化, 同时北风使海冰往南漂移扩散, 造成巴伦支海北部海冰范围在2014年偏多。2014年北地群岛航线开通时间范围大约在8月上旬到10月上旬, 时长约两个月。新西伯利亚群岛及附近海域的开通时间稍早于北地群岛, 但关闭时间比北地群岛晚, 所以 2014年东北航道全线开通的时间主要受制于北地群岛附近海冰变化。     

基于CryoSat-2测高数据的北极格陵兰海海冰干舷高提取研究

北极是全球气候和环境变化的驱动器之一,获取北极海冰的时空特征和变化规律对研究北极以及全球气候变化意义重大。格陵兰海是北极海冰剧烈变化的区域之一,采用CryoSat-2的雷达测高数据,获取了格陵兰海的海冰干舷高分布,并利用波弗特环流计划(BGEP)仰视声呐(ULS)数据进行了验证。研究结果表明,格陵兰海海冰干舷高和分布范围存在明显的季节性变化特征,具体体现在格陵兰海海冰从10月份进入冻结期开始,海冰分布范围不断扩张,海冰干舷高也逐渐增大,2月份平均干舷高达到最大(0.2 m),之后格陵兰海海冰开始消融,覆盖范围不断内缩,9月海冰干舷高降至最小(0.13 m)。     

Development of a chironomid-based air temperature inference model for the central Canadian Arctic

Subfossil midge remains were identified in surface sediment recovered from 88 lakes in the central Canadian Arctic. These lakes spanned five vegetation zones, with the southern-most lakes located in boreal forest and the northern-most lakes located in mid-Arctic tundra. The lakes in the calibration are characterized by ranges in depth, summer surface-water temperature (SSWT), average July air temperature (AJAT) and pH of 15.5 m, 10.60°C, 8.40°C and 3.69, respectively. Redundancy analysis (RDA) indicated that maximum depth, pH, AJAT, total nitrogen-unfiltered (TN-UF), Cl and Al capture a large and statistically significant fraction of the overall variance in the midge data. Inference models relating midge abundances and AJAT were developed using different approaches including: weighted averaging (WA), weighted averaging-partial least squares (WA-PLS) and partial least squares (PLS). A chironomid-based inference model, based on a two-component WA-PLS approach, provided robust performance statistics with a high coefficient of determination (r ² = 0.77) and low root mean square error of prediction (RMSEP = 1.03°C) and low maximum bias. The use of a high-resolution gridded climate data set facilitated the development of the midge-based inference model for AJAT in a region with a paucity of meteorological stations and where previously only the development of a SSWT inference model was possible. David Porinchu and Nicolas Rolland contributed equally to the work.     

北极地区20世纪温度变化趋势的不确定性

北极作为地球的冷源之一,对于地球气候系统起着重要的调节作用.本研究通过分析和总结北极地区器测数据和模拟集成结果,以及最近2 000 a来的温度记录,得出如下结果：1）格陵兰冰盖表层大气温度记录显示,20世纪存在1923—1965年和1994年—至今2个相对温暖时段,且前者更为温暖,温度变化幅度远大于北半球的平均温度.2）北极地区20世纪温度上升是客观存在的,其夏季温度和年平均温度呈现一致变化,未发现明显的温度异常信号.3）定量重建的古气候记录显示了北极地区20世纪升温的特征,但不同记录揭示的升温幅度存在差异.与器测结果不同,多条重建记录未能揭示自1994年至今的升温阶段,反映了古气候载体对气候响应的复杂性,揭示出北极地区未来气候变化趋势存在不确定性.在全球变化备受关注的背景下,北极地区对气候变化研究的重要性日益显现,在做出明确结论之前,需要进一步加大研究力度.     

Mechanism and effects of the increase in winter temperatures in the Arctic region on cold winters in Heilongjiang Province,Northeast China for the period 1961–2018

With the advent of climate change,winter temperatures have been steadily in-creasing in the middle-to-high latitudes of the world.However,we have not found a corre-sponding decrease in the number of extremely cold winters.This paper,based on Climatic Research Unit (CRU) re-analysis data,and methods of trend analysis,mutation analysis,correlation analysis,reports on the effects of Arctic warming on winter temperatures in Hei-longjiang Province,Northeast China.The results show that:(1) during the period 1961-2018,winter temperatures in the Arctic increased considerably,that is,3.5 times those of the Equator,which has led to an increasing temperature gradient between the Arctic and the Equator.An abrupt change in winter temperatures in the Arctic was observed in 2000.(2) Due to the global warming,an extremely significant warming occurred in Heilongjiang in winter,in particular,after the Arctic mutation in 2000,although there were two warm winters,more cold winters were observed and the interannual variability of winter temperature also increased.(3)Affected by the warming trend in the Arctic,the Siberian High has intensified,and both the Arctic Vortex and the Eurasian Zonal Circulation Index has weakened.This explains the de-crease in winter temperatures in Heilongjiang,and why cold winters still dominate.Moreover,the increase in temperature difference between the Arctic and the Equator is another reason for the decrease in winter temperatures in Heilongjiang.     

Characteristics of precipitation in northern Mauritania and its links with sea surface temperature

This paper deals with the periodic fluctuation of precipitation at three meteorological stations (Atar, Chenguitti, and Akjoujt) in the Adrar and Inchiri provinces in northern Mauritania and its links with sea surface temperature (SST). Trends for these three meteorological stations were evaluated using the Mann–Kendall (MK) nonparametric test, regression analysis, and autocorrelation for persistence analysis. The MK test showed a significant decreasing trend for Akjoujt and an insignificant trend for the other rainfall time series. However, the decreasing linear regression trends were highly significant for the different time series. On the other hand, persistence analysis indicated the presence of a linear Markov type. The cycles found by power spectrum analysis ranged from 0.5 years to about 11 years. The possibility of a connection between precipitation in this region and sunspot numbers was suggested. SST of the Atlantic Ocean, Indian Ocean, and Mediterranean Sea have significant cross-correlations with precipitation in the study area. The El Niño-Southern Oscillation effect was found to be marginal.     

Seed germination of Southern Chihuahuan Desert plants in response to elevated temperatures

High temperature is one of the main factors that prevent germination, through premature aging of the embryo. The high temperatures reached in the soil of arid environments can affect seed survival and plant establishment. In this study we tested whether seed exposure to high temperature (40 °C and 70 °C) affected germination of eight species common to the Southern Chihuahuan Desert, and used for fodder, firewood and timber, fiber, edible flowers, fruits and stems. The responses to heat varied between species. Two of the tested species were not affected by heat exposure; for two other species germination was higher, and for the remaining four, germination was lower. There was also a delay of germination after heat exposure. Seeds of three species germinated >1 d slower after exposure to high temperatures. These results could help establish management programs for these Chihuahuan desert species under a climate change scenario.     

北极拉普捷夫海春季冰藻和浮游植物群落结构及生物量分析

对1999年春季采集于北极拉普捷夫海东南部的冰藻和冰下浮游植物群落的种类组成进行了分析,并对丰度和生物量进行了统计和对比。藻种以硅藻占绝对优势,其中又以羽纹硅藻为主。优势种集中,主要包括海洋拟脆杆藻(Fragilariopsisoceanica)、圆柱拟脆杆藻(F.cylindrus)、寒冷菱形藻(Nitzschiafrigida)、普罗马勒菱形藻(N. promare)、带纹曲壳藻(Ach nanthestaeniata)、新寒冷菱形藻(Nitzschianeofrigida)、大洋舟形藻(Naviculapelagica)、范氏舟形藻(N. vanhoeffenii)、北极直链藻(Melosiraarctica)、北方舟形藻(N. septentrionalis)、新月细柱藻(Clindrothecaclosterium)和绿藻门的塔形藻(Pyramimonassp. )。微藻主要集中在冰底10cm,丰度为14. 6-1562. 2×104 cells·L-1,平均为639. 0×104 cells·L-1;生物量为7. 89-2093. 5μgC·L-1,平均为886. 9μgC·L-1,总体上比次冰底高1个数量级,比冰下表层水柱高2个数量级。冰底20cm冰柱的累计丰度和生物量平均分别为冰下20m水柱累计量的7. 7和12. 2倍,显示冰藻在春季海冰融化前在近岸生态系统中的重要作用。尽管各站位冰底和冰下表层水柱藻类群落的相似性普遍不高,但整个调查海域冰底和冰下水柱优势种极为相似,春季期间冰藻对冰下浮游植物群落的影响明显。由于     

Effect of shipping activity on warming trends in the Canadian Arctic

This paper presents a detailed account of the effect of shipping activity on the increasing trends of air temperatures in the Canadian Arctic region for the period of 1980–2018. Increasing trend of temperature has gained significant attention with respect to shipping activities and sea ice area in the Canadian Arctic. Temperature, sea ice area and shipping traffic datasets were investigated, and simple linear regression analyses were conducted to predict the rate of change(per decade) of the average temperature, considering winter(January) and summer(July) seasons. The results indicate that temperature generally increased over the studied region. Significant warming trend was observed during July, with an increase of up to 1℃, for the Canadian Arctic region. Such increasing trend of temperature was observed during July from the lower to higher latitudes. The increase in temperature during July is speculated to increase the melting of ice. Results also show a decline in sea ice area has a significant positive effect on the shipping traffic, and the numbers of marine vessel continue to increase in the region. The increase in temperature causes the breaking of sea ice due to shipping activities over northern Arctic Canada.     

河北省气候变化对AO因子的响应探讨

 利用河北省72个气象台站1961-2010年逐月气温数据,选择Mann-Kendall突变趋势检验、Mann-Kendall突变检验、Sen’s坡度估计、一元方差分析等方法判断了河北省气温变化的趋势和突变时间,分析了气温变化的区域和季节特征,并探讨了气温变化特征与北极涛动、经纬度及海拔高度等影响因子的关系。结果表明：（1） 河北省整体气温显著上升,年均温平均增幅0.30 ℃/10 a,四季增温幅度冬>春>秋>夏;坝上高原和冀西北间山盆地区增温幅度较大;（2） 河北省增温突变集中在1986-1994年;冬季和春季增温突变较显著;年均温增温突变时间北部早于南部;（3） CO₂排放量持续增加、1995年之前AO指数的增强可能是河北省近50 a增温的主要原因;高纬度、高经度、高海拔、盆地以及无森林和湿地调节的地区增温显著,这些因素对区域增温具有放大作用,是影响河北省气候变化对AO响应程度的重要因素。     

北极水域船舶事故特征及关联规则分析

北极海冰的大量融化,加速了北极航道开发和利用,对北极水域船舶事故风险管理提出了更高的要求。本文以2008—2017年的北极水域船舶事故数据为样本,运用数据挖掘技术和方法,对北极水域船舶事故进行了时空特征分析,并对船舶属性与事故属性之间的潜在映射关系进行了关联规则挖掘。结果表明:北极水域事故数逐年呈上升的趋势,事故主要发生在巴伦支海东部的俄罗斯摩尔曼斯克港口水域和挪威北部水域;北极水域严重事故受船舶总吨、船旗国、船舶类型、事故类型、事故水域等变量的影响,船舶尺度较大的船舶更容易造成严重事故;北极水域俄罗斯籍渔船的严重事故,很多是由机损事故引发的,但很少造成环境污染。研究结论可辅助海事管理部门和航运企业开展北极水域船舶事故预防和风险管理工作。     

Quantitative estimates of recent environmental changes in the Canadian High Arctic inferred from diatoms in lake and pond sediments

Diatoms were examined in three lacustrine sediment records from Alert, northern Ellesmere Island, and from Isachsen, Ellef Ringnes Island. Diatom assemblages changed markedly since the mid-19th century following relatively stable community composition that spanned centuries to millennia. Three different assemblages, primarily composed of Fragilaria pinnata, Diadesmis spp., or Pinnularia spp., dominated the pre-1850 period at the three sites, but were replaced with different, more diverse assemblages in recent sediments. These species shifts occurred in the mid- to late-19th century in the Isachsen sites, and in the mid- to late-20th century in our Alert site. This difference in timing appears to be a result of the different sensitivities of lakes and ponds to environmental change, rather than of site-specific chemical properties. Reconstructions of pH using diatom inference models indicated increases from 0.5 to 0.8 pH units at these sites over this period of assemblage change. The diatom-inferred pH record from Alert showed agreement with measured climate data from Alert over the last 30 years. These marked community changes suggest that these sensitive high arctic sites have recently crossed important ecological thresholds due to environmental change, most likely related to recent warming.     

On climate variability in Northeast of Brazil

The time-series (annual period and dry- and wet-season) of eight climatic variables were analysed to ascertain the existence of climate variability in Northeast of Brazil. Results indicated generally increasing trends in most of these variables (statistically significant at p<0.01 or <0.05) by Mann–Kendall test. However, relative humidity and rainfall presented decreasing behavior. The study showed that most of the stations studied are going through a process of environmental dryness. The results also suggest that the historical trends may be related to climate variability in Northeast of Brazil, which affects both semi-arid and coastal part of the region.