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1.
依托2012 年第五次北极科学考察分析了夏季挪威-格陵兰海域营养盐和光合色素的分布情况, 探讨 水团输送对该海域营养盐分布及对该海域浮游植物群落结构分布的影响。结果显示挪威海和格陵兰海域调 查站位上层(200 m)水体中AT 断面的硝酸盐、磷酸盐及硅酸盐平均浓度分别为9.0(±5.0)、0.65(±0.29)和 1.8(±1.6) μmol·L–1, BB 断面的硝酸盐、磷酸盐及硅酸盐平均浓度分别为8.9(±3.8)、0.71(±0.22)和1.8(± 1.6) μmol·L–1。挪威海和格陵兰海域上层水体中硅酸盐相对于硝酸盐远远不足, 且呈显著硅限制, 该限制随 纬度的升高有所减轻, 表现为北冰洋入流水的硅酸盐输送。光合色素与温度和营养盐的关系表现为: 与温度 呈正相关, 与营养盐呈负相关。光合色素的分布结果表明, 挪威-格陵兰海域浮游植物群落表层以硅藻或硅 藻和定鞭金藻为主, 次表层(叶绿素最大层)则以硅藻为优势种, 并且硅藻更易聚集于混合层下方温跃层上 方, 定鞭金藻在表层水体低营养盐的条件下更具竞争力。此外, 由于受大西洋入流分支的影响, 浮游植物向挪 威-大西洋流流经区域聚集(温度更高且营养盐充分), 形成区域浮游植物分布差异。  相似文献   

2.
Oceanographic data covering the period 1950–1998 are used to determine interannual variations in the convection intensity and water mass structure in the Greenland Sea and adjacent areas. Extremely cold winters throughout 1965–1970 assisted intensification of the water vertical exchange in the Greenland and Norwegian seas. As a result, cold and fresh Greenland Sea Deep Water (GSDW) production was extremely high in the central Greenland Sea while in the southern Norwegian Sea warm and salty water spread downwards. The recent rapid warming in the Greenland Sea Gyre interior from 1980 originates, we argue, from an increase in the Atlantic Water (AW) temperature due to the advection of warm waters into the region with the Return Atlantic Current. The negative water temperature and salinity trends in the upper 300 m layer of the Atlantic Water in the Norwegian Sea prevailed during 1950–1990, whereas during 1980–1990 the water temperature trends are indicative of warming of that layer. Observation series obtained onboard the Ocean Weather Ship Mike confirmed the existence of layers with advectiondriven high oxygen concentrations in intermediate and deep layers. The depth of oxygen maxima and the values of oceanographic parameters at this horizon can be regarded as indicators of the convection intensity in the Arctic domain. A simultaneous rise in NAO index and GSDW temperature points to a link between atmospheric and thermohaline circulation. Weakening in water exchange with the North Atlantic could be the reason for the Polar Water recirculation increase within the Nordic seas.  相似文献   

3.
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   

4.
The sea ice cover in the Arctic Ocean has been reducing and hit the low record in the summer of 2007.The anomaly was extremely large in the Pacific sector. The sea level height in the Bering Sea vs.the Greenland Sea has been analyzed and compared with the current meter data through the Bering Strait.A recent peak existed as a consequence of atmospheric circulation and is considered to contribute to inflow of the Pacific Water into the Arctic Basin.The timing of the Pacific Water inflow matched with the sea ice reduction in the Pacific sector and suggests a significant increase in heat flux.This component should be included in the model prediction for answering the question when the Arctic sea ice becomes a seasonal ice cover.  相似文献   

5.
在北极地区,有接通北美洲、欧洲北部和亚洲北部国家之间距离最短的直线路线,所以北极地区的战略位置日益重要。大气波导是重要的电波环境,利用大气波导可实现超短波、微波频段的超视距探测和通信应用。因此,研究北极大气波导有重要的意义。本文利用2007年1月—2016年12月十年的气象探空数据,统计分析了北极16个站点大气波导的时空分布,给出了大气波导出现概率与其波导层厚度、强度特征量的统计特征,并从天气和气候学角度初步探讨了其成因。统计结果显示:1.北极地区大气波导平均出现概率低于50%,且表面波导出现概率高于悬空波导; 2.表面波导层厚度、强度分别在30 m以下和10 M以下,悬空波导层厚度在40—80 m,强度小于10 M; 3.北欧海区和格陵兰岛为北极波导高发区,欧亚大陆的北部边缘为无波导区; 4.表面波导高发区在北欧海区和格陵兰岛,北大西洋暖流、格陵兰冷高压及极夜期的辐射逆温是表面波导形成的可能原因; 5.悬空波导高发区在北欧海区和白令海峡东北部区域,且在7—8月份的暖季极昼期间为其高发季,北欧海区暖季海雾、白令海峡东北部区域暖季受北极锋影响是悬空波导形成的可能原因。  相似文献   

6.
The spatial distribution of heat and freshwater content and potential energy of a several hundred metre thick surface layer are computed for the Nordic seas and adjacent parts of the northern North Atlantic and the Arctic Ocean using a total of almost 100 000 hydrographic stations. The fields clearly show the major features of the area's circulation, with warm salty water in the eastern part and fresher, colder water in the western part. Comparisons with published estimates show that the potential energy field, representing the baroclinic part of the flow, accounts for about 30 % of the total flow but roughly 100 % of the flow of Polar Water in the northern part of the East Greenland Current, about 50 % of the total flow in the Norwegian Atlantic Current, and just a small fraction of the flow in the eastern part of Fram Strait. This suggests that the barotropic circulation is quite important in many parts of the Nordic seas. The barotropic circulation is also clearly seen by its effects on the integrated fields with isolines following deep bathymetric contours. We speculate that the barotropic circulation in combination with topographic obstacles, like the Greenland–Scotland Ridge and the ridge system in the Jan Mayen area, may have large impact on the spreading of freshwater and heat in the Nordic seas.  相似文献   

7.
梁敏仪  史久新 《极地研究》2015,27(4):379-391
利用2003—2011年AMSR-E(Advanced Microwave Scanning Radiometer-Earth Observing System)日平均海冰密集度数据,对楚科奇海阿拉斯加沿岸冰间湖进行了分析。针对冰间湖的特点,在阈值法的基础上,通过统计冰间湖出现的频率,限定冰间湖的最大范围,区分各个冰间湖。通过计算阿拉斯加沿岸冰间湖的面积,结合NCEP-DOE(National Centers for Environmental Prediction-Department of Energy)再分析风场数据和白令海峡潜标观测的温盐和海流数据,初步探讨冰间湖发生和发展的规律。为了排除海冰外缘区对判断冰间湖的影响,研究仅限于白令海峡完全冰封的1—4月,可得到以下结论:阿拉斯加西北沿岸海域每年冬季都会出现5个冰间湖,多数时间为紧靠大陆边缘的沿岸冰间湖,巴罗角附近海岸在3月和4月会出现位于沿岸固定冰之外的裂缝冰间湖。冰间湖面积每天都发生变化,表现出天气尺度的变化特征,经历长达数日的发展和消失的过程,与风场的转换有密切关系。离岸风有利于沿岸冰间湖的扩展,但是该海域1—4月的盛行风为东北风和北风,对于多数冰间湖而言为沿岸风,不利于冰间湖的形成,因而冰间湖有时消失长达数十日。在偏北风的影响下,太平洋入流对北部冰间湖几无作用,而对南部冰间湖的空间分布有着重要影响。  相似文献   

8.
The importance of the Hell Gate Polynya to marine birds in High Arctic Canada has not been assessed for two decades. Our breeding season surveys in 2002–04 found 19 species of marine birds using the polynya, in annual numbers perhaps reaching 25000 individuals. The site appears to support nationally significant populations of northern fulmar ( Fulmarus glacialis ), Thayer's gull ( Larus thayeri ) and High Arctic brant ( Branta bernida hrota ), as well as locally important numbers of other species including common eiders ( Somateria mollissima borealis ) and black guillemots ( Cepphus grylle ). The polynya may be particularly important for migration, as many species are observed here earlier than elsewhere in the High Arctic.  相似文献   

9.
CTD observations from the southern Weddell Sea in 1977 show that Ice Shelf Water originating under the floating Filchner Ice Shelf overflows at the sill of the Filchner Depression and can be identified on the continental slope at more than 2000m depth. Intrusions of Weddell Deep Water upon the shelf are especially noticeable in the region of dense shelf water outflow and are possibly driven by the outflow. Anomalous low core temperature of Weddell Deep Water is probably related to winter convection in the Weddell Polynya. Anomalous CTD stations at the periphery of the 1976 winter polynya region indicate that deep convection phenomena, as reported by Gordon (1978), are perhaps quite common. The observations indicate that double diffusive convection is important for vertical heat transport in the central Weddell Sea.  相似文献   

10.
Sea-associated birds were recorded during systematic aerial surveys of marine mammals in south-western Greenland, the Davis Strait and southern Baffin Bay in March 1981, 1982, 1991, 1993 and in April 1990. Most surveys included the northern part of the south-west Greenland Open Water Area, which in most years lies between 62° and 67°N. but none of the area south of 63°N was surveyed. The bird data are generally semi-quantitative and provide information on distribution and relative abundance in different areas during different years, under different ice conditions.
In all years, regardless of ice conditons, large concentrations of king eiders Somateria spectabilis were found in water <50m deep on the shallow banks off south-west Greenland, especially on the northern portion of the Store Hellefiskebanke. We estimate that in 1981 and 1982 about 270000 king eiders overwintered on the banks off south-west Greenland.
Compared to king eiders, flocks of common eiders Somateria mollissima were considerably more dispersed. They were found mainly close to shore off south-west Greenland, where they were distributed along rocky coastlines.
A few thousands of large guillemots Uria spp. were recorded in the study area in March 1981, 1982, 1991 and 1993, but large numbers (>65000 birds) were recorded north of the south-west Greenland Open Water Area in April 1990. indicating that northward spring migration was underway at this time.  相似文献   

11.
Late glacial palaeoceanography of Hinlopen Strait, northern Svalbard   总被引：3，自引：0，他引：3  
Timing and structure of the Late and post-glacial development of the northern Svalbard margin, together with the initial influx of Atlantic water into the Arctic Ocean are still very poorly constrained. We investigated a sediment core (NP94-51) from a high accumulation area on the continental shelf north of Hinlopen Strait with the purpose of resolving the timing and structure of the last deglaciation. Detailed analyses of ice-rafted detritus, benthic and planktonic foraminiferal fauna, diatom flora, grain size and radiocarbon dates are used to reconstruct the palaeoceanographic evolution of the area. Our results indicate that the disintegration of Hinlopen Strait ice and possibly the northern margin of the Svalbard Ice Sheet commenced between 13.7 and 13.9 14C Ky BP. Influx of subsurface Atlantic waters into the area (12.6 14C Ky BP) and the retreat of the sea ice cover, with the accompanying opening of the surface waters (10.8 14C Ky BP), happened at different times and both much later than the disintegration of the ice sheets. The transition into the Holocene shows a two-step warming.  相似文献   

12.
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   

13.
通过分析中国第28次南极考察队于2011年12月至2012年1月在南极半岛北端周边海域获得的5条断面CTD观测温盐剖面数据, 进一步认识了该海域的水团组成和水交换情况。观测区域南部的鲍威尔海盆及周边深海区, 可以观测到保持了较显著高温核心的威德尔深层水、密度大于28.27 kg·m-3的威德尔海深层水以及温度低于－0.7 ℃的威德尔海底层水。周边陆坡上的威德尔海深层水则表现出因与周围水体发生混合而核心性质减弱的特征。在菲利普海岭、埃斯佩里兹海槽等复杂地形处, 观测到的对应于威德尔海深层水深度的混合与热盐入侵过程更为显著。威德尔海深层水能够到达南设得兰群岛以北的象岛东北面海域, 但是高盐核心加深至1 500 db, 并上覆温度基本不变但盐度随深度显著增大的较暖水体, 表明威德尔海深层水经历了不同的路径和变性过程。布兰斯菲尔德海峡中没有绕极深层水大规模侵入的迹象, 但是乔治王岛周边陆架上可能存在涡旋等中尺度过程, 会影响德雷克海峡与布兰斯菲尔德海峡之间的水交换。  相似文献   

14.
The origin of the large positive anomaly of the Fram Strait sea ice export which occurred in winter 1994/95 is analysed on the basis of a model simulation of the Arctic sea ice cover over the period 1993-98. The overall intra-annual and interannual variability in the model is in good agreement with observational estimates and the 1994/95 anomaly is well reproduced with an amplitude amounting to half of the mean winter value. Model results suggest that, concomitant to anomalous export velocities, larger than usual ice thickness in the strait contributes to the outstanding amplitude of the anomaly. Analysis on the ice thickness evolution in the strait indicates that the thick ice advected in Fram Strait at the end of the fall of 1994 originates in the anomalous cyclonic wind stress which prevailed during the preceding summer. This anomalous wind stress resulted in persistent convergence of the ice flow against the northern coasts of Canada and Greenland and in the formation of a large thickness anomaly north of Greenland. The anomaly then feeds the Fram Strait ice flow during those following winter months when the local wind forcing in the strait favours ice drift from the north-west. Our results suggest that short-term wind stress variations resulting in local thickness changes to the north of Fram Strait can lead to substantial variability of the Fram Strait ice export.  相似文献   

15.
1999年夏季中国首次北极考察区水团特征   总被引：11，自引：3，他引：11       下载免费PDF全文
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   

16.
对中国第四次北极科学考察在楚科奇海获取的悬浮体样品进行悬浮体及其颗粒组分特征的分析,旨在了解楚科奇海悬浮体分布、成因特征以及其沉积学意义。研究发现,楚科奇海中部悬浮体浓度最低,而在靠近白令海峡的南部海域和中北部海域,中下层海水中发现两个悬浮体浓度高值区。楚科奇海阿拉斯加沿岸和巴罗峡谷底层海水中,悬浮体浓度相对较高。扫描电镜分析结果显示,楚科奇海南部和中北部中下层海水中的悬浮体,主要以硅藻为主,但这两个海域的硅藻优势种明显不同。阿拉斯加沿岸和巴罗峡谷中的悬浮体,以生物碎屑为主。结合楚科奇海温度、盐度资料,楚科奇海南部和中北部高浓度悬浮体分别受经白令海峡夏季入侵的太平洋海水和楚科奇海冬季残留水的控制,而阿拉斯加沿岸和巴罗峡谷中下层的悬浮体,则受阿拉斯加沿岸流的控制。  相似文献   

17.
中国东北夏季温度年代际变化特征   总被引：4，自引：0，他引：4  
东北地区夏季温度变化主要有4个独立模态,其中EOF1呈全区一致型为第一模态,占总方差贡献的72%左右,其时间系数呈现多年代际尺度变化;其他3个模态仅分别占总方差贡献的10%、4%和3%,表现出受海洋、地形及纬度差异的影响,呈南北向、东西向和山脉与平原地区的反向异常分布型;突变和小波分析进一步揭示EOF1模态的多年代际尺度变化具有突变性质,2007~2010年受20 a左右周期影响,东北地区温度变化全区一致的模态时间系数处于负值为主的阶段,值得关注。东北地区夏季温度变EOF1模态与北半球500 hPa高度场和对流层中上层纬向风场(西风急流)在30oN~40oN呈环球尺度带状显著正相关分布,在东北亚地区纬度较高,可达60oN附近,而且该区500 hPa高度场与东北夏季温度EOF1模态多年代际变化近于同步。EOF1模态与靠近亚洲大陆沿岸和西太平洋暖池(包括印度洋的中部和北部)、南太平洋环澳大利亚、靠近北美大陆及北大西洋北部的漂流区和北赤道漂流区的海表温度存在显著的同步正相关,而与太平洋海表温度的年代际振荡模态亦有较显著的正相关;表明东北地区夏季温度的EOF1模态与北半球海-气系统多年代际变化联系密切,同时也受到全球变暖的影响。  相似文献   

18.
ABSTRACT. Two well dated Holocene sediment records bordering the Denmark Strait region have been used to reconstruct past climate variability. The content of biogenic silica, classic and organic material and moss in a lacustrine record from Lake N14 has been used to infer past variability in precipitation and temperature in southern Greenland. Sedimentologic and petrologic composition of sand in a shelf sediment record from the Djúpáll trough is used to infer past variability in the northwestern storm activity on northwestern Iceland, which probably also affected the inflow of polar waters from the East Greenland Current. Our evaluation of these records with a number of previous studies from the region documents Holocene climatic optimum conditions peaking between 8000 and 6500 calendar years before present (cal yr BP). Mid-Holocene climate deterioration set in around 5000 cal yr BP followed by a further marked setback around 3500 cal yr BP. A stacking of climate variability on a centennial timescale from previous studies in the area shows a fairly good correspondence to the timing of marked cold and warm events as evidenced from the Lake N14 and the Djúpáll trough records. Cooler periods are explained as the response to marked incursions of ice-laden polar water from the Arctic Ocean to the Denmark Strait region. Cool northerly and northwesterly winds along the East Greenland coast in relation to frequent strong atmospheric low pressure in the Barents Sea, coupled with strong high pressure over Greenland, would have favoured southward export of polar waters. A comparison with the proxy records of nuclide production (14C and 10Be) suggests that solar activity may have had some influence on the atmospheric pressure distribution in the Denmark Strait region.  相似文献   

19.
The nutrient status of the various water mass structures within a large sampling grid around Elephant Island are reported and the nutrient concentrations relative to jata from the physical and biological components of the Antarctic Marine Living Resources Programme are discussed. Concentrations of silicic acid, nitrate and phosphate (Si/N/P) were measured in the upper water column during January-March of three successive years. Samples were taken from eleven depths at 17 stations in 1991, and at four depths at 144 stations in 1992 and 182 stations in 1993. There was considerable variability in the concentrations of all three nutrients within the study area, but silicic acid showed the greatest variance among the water masses present in the sampling grid. The ratios (Si/N/P) of the nutrient deficits (difference in winter and summer values) in the upper 100 m differed considerably in Drake Passage waters as compared to Bransfield Strait waters, with both nitrate and silicic acid showing the greatest variance. Nutrient deficits did not increase from January to February, indicating that rates of replenishment of nutrients to the euphotic zone by physical processes and/or biological regeneration were approximately equal to the rate of uptake and assimilation by phytoplankton during that time period. The seasonal deficits, however, were substantial. Estimates of daily rates of primary production based on these nutrient deficits were comparable to the rates as measured by radiocarbon for Drake Passage waters, but much smaller for Bransfield Strait waters.  相似文献   

20.
加拿大海盆的营养盐极大   总被引：6，自引：0，他引：6       下载免费PDF全文
根据 1 999年和 2 0 0 3年中国北极科学考察航次 ,从Canada海盆收集温、盐、深和营养盐浓度数据 ,用文献报道的低浓度1 2 9I和高浓度金属钡 (Ba)来指示太平洋源水、用相应的高浓度1 2 9I和低浓度Ba来指示大西洋源水 ,划分了该海盆物理化学特征的 4个水团。表层水 ( <40m)的盐度从 2 5至 31 .6;硝酸盐处于耗尽水平 ,而磷酸盐和硅酸盐处于最低水平。营养盐再生水大致位于 40- 2 0 0m ;盐度特征为 31 .6- 33.1 ;营养盐浓度一致增至最高 ;极大峰的盐度在 33.1附近 ,其位温则处于最低水平 (约 - 1 .5°C)。混合水 (深约 2 0 0- 385m)盐度从 33.1至 34.8;位温从局域最低升至整个水柱最高的 0 .5 0- 0 .65 7°C ;营养盐则逐渐降低。深层水深度变化较大 ( 385m至 1 90 0m以下海底 ) ;但其盐度变化较小 ( 34.8- 34.9) ;位温则从最高降低到 - 0 .4至 - 0 5 4°C ;营养盐均轻微增加。结合文献中对于营养盐极大的年际观测 ,1 2 9I、Ba与氯氟烃CFC 1 1的浓度及3H 3He示踪年龄的结果分析表明 ,营养盐再生水是无季节性变化的、高年龄 (约 8- 1 5年 )的太平洋源水 ;深层为大西洋源水 ;而混合水团即为上述 2大源水的混合层。硅酸盐和磷酸盐的强极大指示优势种硅藻及其再生主导太平洋源水。  相似文献   

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