共查询到20条相似文献，搜索用时 31 毫秒
1.
Circulation in the Arctic Ocean 总被引：7，自引：0，他引：7
E. Peter Jones 《Polar research》2001,20(2):139-146
Much information on processes and circulation within the Arctic Ocean has emerged from measurements made on icebreaker expeditions during the past decade. This article offers a perspective based on these measurements, summarizing new ideas regarding how water masses are formed and how they circulate. Best understood at present is the circulation of the Atlantic Layer and mid-depth waters, to depths of about 1700 m, which move in cyclonic gyres in the four major basins of the Arctic Ocean. New ideas on halocline formation and circulation are directly relevant to concerns regarding changes in ice thickness. The circulation of the halocline water in part mimics that of the underlying Atlantic Layer. A number of large eddies contributing to water mass transport have been observed. The circulation of freshwater from the Pacific Ocean and from river runoff has been better delineated. Circulation within the surface layer resembles the circulation of ice, but is different in several respects. Least understood is the circulation of the deepest waters, though some information is available. Recent observed changes in the surface waters and warm Atlantic Layer have been correlated with the North Atlantic Oscillation. While these changes are dramatic, the qualitative circulation pattern may not have been altered significantly. 相似文献
2.
依据 1 999年 7月至 9月中国首次北极考察队在白令海、楚科奇海和南加拿大海盆的现场调查资料 ,本文分析了三个海区的水团特征 :( 1 )白令海水团主要由季节变化显著的白令海上层水团和中层水团以及深层水团组成 ;( 2 )楚科奇海水文特征受融结冰过程影响较大 ,1 999年7月和 8月差异较大 ,其水团主要为浅海变性水团 ,包括两个次级水团 ,楚科奇海夏季水和来自北太平洋以及北冰洋变性的外海入侵水 ;( 3)南加拿大海盆的水团主要由受融结冰过程影响的表层水团、源于太平洋水的次表层水、源自北大西洋的中层水团和深层水团组成 相似文献
3.
北极环极边界流是新近揭示的重要海洋现象 ,是对北冰洋海洋环流长期研究结果综合得到的概念。在本文中 ,详细介绍了北极环极边界流的主要结构和水团特征 ,论述了研究北极环极边界流的意义和前景 ,深入探讨了北极环极边界流面对的科学问题 ,指出了解决这些问题的关键科研工作。文章指出 ,从整体上研究北极环极边界流是非常重要的 ,需要全面考察北冰洋的质量和能量平衡、深层水通风过程以及水体的混合过程。在进一步的研究工作中需要更多的有针对性的现场观测、开展多学科协作研究。数值模拟仍然是北极环极边界流的重要研究手段 ,需要改善数值模式 ,提高数值模拟的质量。 相似文献
4.
Modeling Arctic Ocean heat transport and warming episodes in the 20th century caused by the intruding Atlantic Water 
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下载免费PDF全文 Jun Takahashi Tatsuo Suzuki Igor V Polyakov Kohei Mizobata Moto Ikeda Fancois J.Saucier Markus Meier 《极地研究》2008,19(2):159-167
This study investigates the Arctic Ocean warming episodes in the 20th century using both a high-resolution coupled global climate model and historical observations .The model,with no flux adjustment,reproduces well the Atlantic Water core temperature(AWCT) in the Arctic Ocean and shows that four largest decadal-scale warming episodes occurred in the 1930s,70s,80s,and 90s,in agreement with the hydrographic observational data.The difference is that there was no pre-warming prior to the 1930s episode,while there were two pre-warming episodes in the 1970s and 80s prior to the 1990s,leading the 1990s into the largest and prolonged warming in the 20th century.Over the last century,the simulated heat transport via Fram Strait and the Barents Sea was estimated to be,on average,31.32 TW and 14.82 TW,respectively,while the Bering Strait also provides 15.94 TW heat into the western Arctic Ocean.Heat transport into the Arctic Ocean by the Atlantic Water via Fram Strait and the Barents Sea correlates significantly with AWCT(C=0.75 ) at 0- lag.The modeled North Atlantic Oscillation(NAO) index has a significant correlation with the heat transport(C=0.37).The observed AWCT has a significant correlation with both the modeled AWCT(C=0.49) and the heat transport(C=0.41). However,the modeled NAO index does not significantly correlate with either the observed AWCT(C=0.03) or modeled AWCT(C=0.16) at a zero-lag,indicating that the Arctic climate system is far more complex than expected. 相似文献
5.
Hydrographic (CTD) observations obtained with R/V'Lance'in July-August 1982 across the Fram Strait are presented. The extent and the presence of traditional water masses such as Atlantic Water, Polar Water and Greenland Sea Deep Water are discussed. The complicated hydrographical structure in the upper water masses due to eddies and fronts near the ice edge is noted. An intermediate water mass characterized by a salinity minimum is found all across the Strait, and is suggested to originate in the Greenland Sea. The deep water in the south-west part of the Strait shows strong horizontal salinity and temperature gradients, and the structure of the corresponding station profiles indicates large hydrographical activity. This is in contrast to the east-north-east part, where the horizontal gradients are much weaker and the profiles much smoother. Thus most of the deep-and bottom-water communication between the Greenland/ Norwegian Seas and the Arctic Ocean seems to take place west of the 0° meridian. 相似文献
6.
Based on temperature reconstruction and proxy data from 14 sites in the Northern Hemisphere, this paper focused on comparing the cycles of temperature variations between the Arctic and other areas, including Atlantic, Europe, China, Asia, Pacific, Indian Ocean, and America during the transition from the last Interstade to the Last Glacial Maximum, from the Last Glacial Maximum to megathermal period in Holocene and the transition of the Little Ice Age (LIA) by the methods of Singular Spectrum Analysis (SSA) and Maximum Entropy Spec-trum (MES). The results showed that environmental changes in the Arctic are most similar to that in the North American and better similar to Asia, Atlantic and Pacific, the least similar to Indian Ocean and Europe. The 1500-year oscillation of temperature existed both in Arctic and Europe. 相似文献
7.
Based on temperature reconstruction and proxy data from 14 sites in the Northern Hemisphere, this paper focused on comparing the cycles of temperature variations between the Arctic and other areas, including Atlantic, Europe, China, Asia, Pacific, Indian Ocean, and America during the transition from the last Interstade to the Last Glacial Maximum, from the Last Glacial Maximum to megathermal period in Holocene and the transition of the Little Ice Age （LIA） by the methods of Singular Spectrum Analysis （SSA） and Maximum Entropy Spectrum （MES）. The results showed that environmental changes in the Arctic are most similar to that in the North American and better similar to Asia, Atlantic and Pacific, the least similar to Indian Ocean and Europe. The 1500-year oscillation of temperature existed both in Arctic and Europe. 相似文献
8.
Svein Østerhus William R. Turrell Bogi Hansen Peter Lundberg Erik Buch 《Polar research》2001,20(2):169-175
The Arctic Mediterranean is the ocean area north of the Greenland-Scotland Ridge. Exchanges between this region and the North Atlantic both provide the main source for production of North Atlantic Deep Water and supply heat and salt to the northern oceans. The exchange occurs through several gaps in the ridge; in terms of volume flux the Iceland-Scotland Gap is the most important one as it carries more than half the total, with approximately three quarters of the total inflow and one third of the total outflow. The Nordic WOCE observational system was initiated to monitor the exchanges through this gap and it has provided data that allow estimates of typical fluxes and their seasonal variation. The flux measurements show that most of the Atlantic inflow to the Arctic Mediterranean returns as overflow and hence the processes forming intermediate and deep waters in the Arctic Mediterranean are the main forcing mechanism for the Atlantic inflow. The inflow between Iceland and Scotland seems to be a maximum in late winter while the Faroe Bank Channel overflow is strongest in late summer. Using the results from the Nordic WOCE system it has been possible to interpret historical observations from Ocean Weather Ship Station M and conclude that the flux of the Faroe Bank Channel overflow decreased in magnitude from 1950 to 2000. 相似文献
9.
近600年来北极与中国气候变化的对比 总被引：2，自引：2，他引：0
许娟 《地理学报(英文版)》2004,14(3):289-295
A compilation of paleoclimate records from lake sediments, trees, ice cores, and historical documents provide a view of China and Arctic environmental changes in the last 600 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic Ocean, Arctic and Greenland and ice cores from the Qinghai-Tibet Plateau, confirming the linkage of environmental changes of different time scales between the Arctic and China. It is shown that the changes of precipitation, temperature and sea ice cover in Arctic were correlated with climate changes in China. This paper also developed a comparative research on the climate changes between Arctic and China both during the Little Ice Age (LIA) and the instrumental observation period. Cycles and trend of temperature variations during LIA and temperature and precipitation during the instrumental observation period are performed. We found some similarities and differences of environmental changes between Arctic and China. 相似文献
10.
A compilation of paleoclimate records from lake sediments, trees, ice cores, and historical documents provide a view of China and Arctic environmental changes in the last 600 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic Ocean, Arctic and Greenland and ice cores from the Qinghai-Tibet Plateau, confirming the linkage of environmental changes of different time scales between the Arctic and China. It is shown that the changes of precipitation, temperature and sea ice cover in Arctic were correlated with climate changes in China. This paper also developed a comparative research on the climate changes between Arctic and China both during the Little Ice Age (LIA) and the instrumental observation period. Cycles and trend of temperature variations during LIA and temperature and precipitation during the instrumental observation period are performed. We found some similarities and differences of environmental changes between Arctic and China. 相似文献
11.
根据 2 0 0 3年中国第二次北极科学考察资料 ,并结合历史现场调查资料和同期的海冰分布 ,分析了白令海峡及其周围海域的水体结构及变化情况 ,得到如下结论 :( 1 ) 2 0 0 3年夏季白令海峡区域层结构季节内变化显著 ,东西部呈两层结构 ,而中部上下水体均匀一致 ,( 2 )白令海峡邻近海域温盐结构是东部高温低盐 ,西部低温高盐 ,西部存在明显上升流特征 ;( 3)白令海峡的水交换以北太平洋水通过白令海峡进入北冰洋为主 ,而温度、盐度的分布也与北向的输运是匹配的。 相似文献
12.
13.
The data from the Southern Ocean observations of World Ocean Circulation Experiment(WOCE) are used for analysis and illustration of the features and spatial distributions of Circumpolar Deep Water(CDW) in the southern Indian Ocean.It is learnt from the comparison among the vertical distributions of temperature/salinity/oxygen along the 30°E,90°E and 145°E sections respectively that some different features of CDW and the fronts can be found at those longitudes,and those differences can be attributed to the zonal transoceanic flow and the merizonal movement in the Circumpolar Deep Water.In fact,the zonal transoceanic flow is the main dynamic factor for the water exchange between the Pacific Ocean and the Indian Ocean or between the Atlantic Ocean and the Indian Ocean,and for the effects on the spatial distributions of the physical properties in CDW. 相似文献
14.
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。 相似文献
15.
研究发现,AMSR-E的垂直极化的18.7 GHz(V18.7)和36.5 GHz(V36.5)的亮温比值在一年冰覆盖区域主要是相应频段的海冰微波发射率之比,而在多年冰覆盖区域受海冰微波发射率和海冰温度共同影响,并且海冰年龄越大亮温比值也越大。应用强度比参数可以比较好地确定冬季一年冰与多年冰之间的阈值,其中,在该阈值处,强度比梯度达到最大。该阈值呈现明显的季节性变化规律,在冬季阈值比较稳定,而在夏季受海水的影响变化范围比较大。应用强度比方法确定的多年冰范围,与NASA Team2(NT2)方法相比在大西洋扇区差异非常小;而在太平洋扇区出现比较大的差异。对比发现强度比法确定的多年冰范围一般大于NT2法。 相似文献
16.
Recently observed changes in the Arctic have highlighted the need for a better understanding of Arctic dynamics. This research addresses that need and is also motivated by the recent finding of two regimes of Arctic ice - ocean wind-driven circulation. In this paper, we demonstrate that during 1946-1997 the Arctic environmental parameters have oscillated with a period of 10-15 years. Our results reveal significant differences among atmosphere, ice, and ocean processes during the anticyclonic and cyclonic regimes in the Arctic Ocean and its marginal seas. The oscillating behaviour of the Arctic Ocean we call the Arctic Ocean Oscillation (AOO). Based on existing data and results of numerical experiments, we conclude that during the anticyclonic circulation regime the prevailing processes lead to increases in atmospheric pressure, in ice concentration and ice thickness, river runoff, and surface water salinity - as well as to decreases in air temperature, wind speed, number of storms, precipitation, permafrost temperatures, coastal sea level, and surface water temperature. During the cyclonic circulation regime the prevailing processes lead to increased air and water temperatures, wind speed, number of storms,open water periods, and to decreases in ice thickness and ice concentration, river runoff, atmospheric pressure, and water salinity. The two-climate regime theory may help answer questions related to observed decadal variability of the Arctic Ocean and to reconcile the different conclusions among scientists who have analysed Arctic data obtained during different climate states. 相似文献
17.
《Polar Science》2014,8(2):73-85
Under-ice observations of algal biomass and seasonality are critical for understanding better how climate-driven changes affect polar ocean ecosystems. However, seasonal and interannual variability in algal biomass has been studied sparsely in perennially ice-covered polar ocean regions. To address this gap in polar ocean observing, bio-optical sensors for measuring chlorophyll fluorescence, optical scattering, dissolved organic matter fluorescence, and incident solar radiation were integrated into Ice-Tethered Profilers (ITPs). Eight such systems have been deployed in the Arctic Ocean, with five profilers completing their deployments to date including two that observed an entire annual cycle in the central Arctic Ocean and Beaufort Sea respectively. These time series revealed basic seasonal differences in the vertical distributions of algal biomass and related bio-optical properties in these two regions of the Arctic Ocean. Because they conduct profiles on daily or sub-daily scales, ITP bio-optical data allow more accurate assessments of the timing of changes in under-ice algal biomass such as the onset of the growing season in the water column, the subsequent export of particulate organic matter at the end, and the frequency of intermittent perturbations, which in the central Arctic Ocean were observed to have time scales of between one and two weeks. 相似文献
18.
结合前人对北冰洋海冰、气候系统的研究成果和 1 999年 8月在北冰洋对海冰的现场观测 ,本文综述了海冰分布、厚度的变化 ,海冰表面特征、积雪变化及北冰洋天气、气候特征和分区。讨论了北极海冰与南极海冰的差异。文章认为 ,北冰洋与周围地区气候变化趋势的不一致 ,主要是由于夏季在北冰洋海冰与开阔水域的相间分布、海冰漂移、融化吸热 ,均衡了周围大气、海洋温度的变化。 相似文献
19.
全球变暖引发了北极地区的快速变化。北极地区苔原冻土带退化、海冰面积退缩和厚度变薄将使北极生态系发生重要变化 ,因而引起碳的生物地球化学循环过程变异。为精确评估北极地区对人为大气CO2 的吸收通量 ,围绕北极苔原、边缘海和极区海域的碳循环研究引起了重视。调查表明 ,北冰洋和亚北冰洋海冰区是海洋吸收大气CO2 的重要汇区 ,北冰洋具有吸收大气CO2 约 1×GtC/a的能力 ,北冰洋夏季冰缘区的长光照和高生产力促进了对大气CO2 的吸收能力 ,北冰洋深水环流和通风作用也有利于表层碳向深水转移。最近有些调查表明 ,如温度继续升高 ,北极苔原有可能从碳汇转变成大气碳源。国际上正加强北极地区碳循环研究的规划和计划 ,企图通过改进现场调查观测手段以及研究方法 ,来定量研究和模式预测变化中北极地区的碳汇潜力及其对地球气候的影响。 相似文献
20.
受常年海冰限制, 北冰洋科学考察程度远低于其他大洋。系统的北冰洋科学调查始于20世纪90年代, 得益于科考破冰船、潜艇等新型调查设备和手段的使用, 科研人员可以主动选择研究目标和对象, 并成功开展了多次地质与地球物理科学考察, 包括海冰科学探索项目(SCICEX)、北极洋中脊考察航次(AMORE 2001)、加科尔洋中脊热液硫化物考察(AGAVE)、北极钻探航次(IODP 302)等。回顾了北冰洋地质与地球物理科学考察进展, 归纳了主要科学问题: 北冰洋主要地质单元大地构造属性及演化、超慢速扩张洋中脊构造与成矿特征、北冰洋新生代古海洋演化。北冰洋地质与地球物理科学考察进展表明: (1)调查手段是制约北冰洋科考水平的关键因素; (2)破冰船与常规探测手段结合是北冰洋科考的重要发展趋势; (3)近底探测手段有助于解决北冰洋主要地质科学问题。 相似文献