近30多年中国东北地区春季寒潮的年代际变化及其可能原因

利用1979~2011年中国东北地区119站气温观测数据,对东北春季寒潮的年代际变化特征进行了分析,并在此基础上通过分析大气环流及北极海冰的变化,对寒潮年代际变化的可能原因进行了探讨。结果表明,东北地区春季寒潮的频次及强度在20世纪80年代末和21世纪初均有明显年代际转折,即20世纪90年代寒潮频次减少而强度增加,21世纪初寒潮频次有所回升但强度减弱。北极新地岛地区海冰的变化可能是造成我国东北地区寒潮活动年代际变化的原因之一。20世纪90年代新地岛附近海冰迅速减少,地表温度明显升高,而高纬海平面气压偏低,此处冷空气不易南下,同时东亚大槽偏强,冷空气强度增加。21世纪初该区海冰减少趋势减缓,冷空气频次有所回升,强度减弱。     

NUMERICAL SIMULATIONS ON INFLUENCES OF VARIATION OF SEA ICE THICKNESS AND EXTENT ON ATMOSPHERIC CIRCULATION*

By using a 2-layer AGCM designed by Institute of Atmospheric Physics,Chinese Academy of Sciences.this paper investigates influences of thickness and extent variations in Arctic sea ice on the atmosphere circulation,particularly on climate variations in East Asia.The simulation results have indicated that sea ice thickness variation in the Arctic exhibits significant influences on simulation results,particularly on East Asian monsoon.A nearly reasonable distribution of sea ice thickness in the model leads directly to stronger winter and summer monsoon over East Asia.and improves the model's simulation results for Siberia high and Icelandic low in winter.On the other hand,sea ice thickness variation can excite a teleconnection wave train across Asian Continent,and in low latitudes,the wave propagates from the western Pacific across the equator to the eastern Pacific.In addition,the variation of sea ice thickness also influences summer convective activitiesover the low latitudes including South China Sea and around the Philippines.Effects of winter sea ice extents in the Barents Sea on atmospheric circulation in the following spring and summer are also significant.The simulation result shows that when winter sea ice extent in the target region is larger (smaller) than normal.(1)in the following spring (averaged from April to June).positive (negative) SLP anomalies occupy the northern central Pacific.which leads directly to weakened (deepened)Aleutian low.and further favors the light (heavy) sea ice condition in the Bering Sea:(2)in the following summer,thermal depression in Asian Continent is deepened (weakened).and the subtropical high in the northwestern Pacific shifts northward(southward) from its normal position and to be strengthened (weakened).     

北极地区盆地分类与油气资源分布规律

北极地区油气资源潜力大,且油气勘探开发尚处于初期,是未来国内外油气工业发展的重要战略领域。文中综合运用全球领先信息服务公司埃信华迈（IHS）和美国地质调查局（USGS）的最新资料及已有研究成果,对北极地区的盆地类型和油气资源分布规律展开研究。结果表明:北极地区至少发育35个沉积盆地,具体划分为裂谷盆地（5个）、被动大陆边缘盆地（16个）、克拉通盆地（5个）、前陆盆地（5个）和大洋盆地（4个）。裂谷盆地是北极地区油气最富集的盆地类型,发现油气探明和控制可采储量（简称2P储量）441.12×108 t油当量,占北极地区油气总储量的74.6%,其次为前陆盆地、被动大陆边缘盆地和克拉通盆地。北极地区大部分油气储于白垩系、侏罗系和二叠系的碎屑岩储集层,仅有小部分油气储于石炭系和泥盆系碳酸盐岩储集层,且不同国家、不同含油气盆地的主力储集层存在明显差异。北极地区的油气主要源自侏罗系和白垩系的烃源岩,三叠系和泥盆系烃源岩次之。此外,复合圈闭是北极地区油气藏的主要圈闭类型,其次是构造圈闭。北极地区盆地类型和油气宏观分布规律的研究将为中国石油公司在北极地区的长远发展奠定基础。      

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。     

Support for the Innuitian Ice Sheet in the Canadian High Arctic during the Last Glacial Maximum

The extent of glacier ice in the Canadian High Arctic during the Last Glacial Maximum (LGM) has been debated for decades. One school proposed a regional Innuitian Ice Sheet whereas another proposed a smaller, non-contiguous Franklin Ice Complex. Research throughout western Nares Strait supports coalescent Innuitian and Greenland ice during the LGM, based on widespread glacial and marine deposits dated by ¹⁴C and amino acid analyses. This coalescence likely promoted a vigorous regional ice flow westward across Ellesmere Island to Eureka Sound. Post-glacial emergence in Eureka Sound suggests a former ice thickness at least as great as that in Nares Strait (≥ 1 km). Recently, independent field studies elsewhere in the High Arctic also support an Innuitian Ice Sheet during the LGM. Collectively, these studies resolve a long-standing debate, and initiate new opportunities concerning the reconstruction of high-latitude palaeoenvironmental and palaeoclimatic change. © 1998 John Wiley & Sons, Ltd.     

1961 - 2018年河西走廊寒潮频次时空变化特征及其环流影响因素研究

寒潮是我国北方地区冬、 春、 秋季节常见气象灾害之一, 产生的危害严重影响社会经济发展和人们生产生活。河西走廊生态环境脆弱且处于寒潮影响的重要区域, 揭示河西走廊寒潮频次时空变化特征可以为农牧业防灾减灾提供参考。基于1961 - 2018年河西走廊12个气象站逐日最低气温数据, 采用数据统计和空间可视化表达方法, 分析近60 a河西走廊寒潮频次时空变化特征, 并探讨北极涛动（AO）异常与寒潮频次的响应关系。结果表明： 从时间上看, 河西走廊的寒潮主要发生在10月至4月, 其中11月、 12月、 4月为寒潮高发时期, 近60 a河西走廊寒潮频次呈现出下降的趋势, 其中在20世纪80年代出现明显的低值, 下降趋势在季节上表现为秋季>春季>冬季; 河西走廊寒潮发生频次具有显著的空间差异, 其中西部地区最多, 东部地区居中, 中部地区最少; 北极涛动（AO）强弱与河西走廊寒潮频次变化具有时空响应关系, 当AO处于负相位时, 河西走廊各气象站寒潮发生频次较多, 并且在河西走廊东部和西部表现的较为明显。     

A life detection problem in a High Arctic microbial community

Fluorescent labeling of bacterial cell walls, DNA, and metabolic processes demonstrates high (potentially single molecule) sensitivity, is non-invasive, and in some cases can differentiate strains and species. Robust microscopes such as the custom instruments presented here can provide good image quality in the field and are potentially suitable for flight. However, ambiguous or false-positive results with bacterial stains can occur and can create difficulties in interpretation even on Earth. We present a “real” life detection problem in a sample of biofilms taken from the Canadian High Arctic. The samples consisted of numerous small sulfur-oxidizing bacteria and larger structures resembling fungi or diatoms. The identity of these latter structures remained ambiguous until electron microscopy and X-ray spectroscopy were performed, indicating that they were unusual sulfur minerals probably precipitated by the bacterial communities. While such mineral structures may possibly serve as biosignatures after the cells have disappeared, it is important that they not be mistaken for cells themselves. It is also possible that unusual mineral structures will be performed under extraterrestrial conditions, so great care is needed to differentiate cell structures from minerals.     

三种北极微藻对不同温度的适应性研究

为了研究北极微藻对不同环境温度的适应性,对分离自北极王湾地区的三种微藻-玛氏骨条藻(Skeletonema marinoi)、小球藻(Chlorella sp.)和衣藻(Chlamydomonas sp.)在不同温度条件下(0℃、4℃和8℃)的生长曲线和抗氧化酶系统进行了测定.结果表明微藻对温度的适应性因种而异:玛氏骨条藻在4℃具有最快生长速率,最高的超氧化物歧化酶(SOD)和过氧化氢酶(CAT)酶活性,及最低的丙二醛(MDA)含量;小球藻的最快生长速率及酶活均在8℃时,MDA含量最低值出现在0℃;衣藻生长情况相差不大,MDA含量的最低值出现在8℃.抗氧化酶系统变化规律也因藻种及温度而异--在0℃与4℃变化时,玛氏骨条藻抗氧化酶系统的三个指标的差异极显著(P<0.01);在0℃与8℃变化时,玛氏骨条藻与小球藻的SOD活性的差异显著(P<0.05),其余两个指标差异不显著;衣藻在三个温度下的三个指标差异均不显著.总体而言,三种藻对三个温度的适应性均较好:其MDA的含量均较低,三种藻各自具有独特的生理代谢机制来适应不同的温度环境.     

北极新奥尔松地区湖泊沉积物色素含量变化及环境意义

大量的古气候资料和现代器测数据表明,最近100年来北极气候经历了明显的变暖过程,这必然会对脆弱的极地湖泊生态系统产生影响。以北极新奥尔松地区的湖泊沉积柱样为研究对象,对其中4种色素(叶绿素及其衍生物CD、总胡萝卜素TC、蓝藻叶黄素Myx和颤藻黄素Osc)进行了分析,结合其他物化指标如碳酸钙含量、TOC等,从历史演化的角度重点探讨了新奥尔松地区最近100年以来湖泊初级生产力演化过程。结果表明,在相对寒冷的小冰期,气候对湖泊中藻类的生长不利,湖泊生产力下降,沉积物中色素含量出现低值,生物硅含量降低;表层5cm(对应约1890AD)沉积物中有机质含量显著升高,各色素含量均明显增加,表明小冰期后气温上升,导致湖泊藻类生长迅速,湖泊生产力大大提高,但此时生物硅仍保持在相对较低的水平,这可能与其他藻类的竞争生长有关。最近100年,沉积物中Osc/Myx比值不断降低,表明该湖泊中蓝藻含量不断上升,暗示北极地区人类活动的增强可能导致湖泊营养水平增加。