Internal tide in the Kara Gates Strait

We observed strong internal tidal waves in the Kara Gates Strait. Internal tides are superimposed over a system of mean currents from the Barents to the Kara Sea. Field studies of internal tides in the Kara Gates were performed in 1997, 2007, and 2015. In 2015, we analyzed data from towed CTD measurements, numerical model calculations, and satellite images in the region. An internal tidal wave with a period of 12.4 h is generated due to the interaction between the currents of the barotropic tide and the bottom relief on the slopes of a ridge that crosses the strait from Novaya Zemlya to the continent. The depths of the ridge crest are 30–40 m. A constant current of relatively warm water flows from the Barents to the Kara Sea. An internal wave propagates in both directions from the ridge. In the Barents Sea, internal waves are intensified by the current from the Barents to the Kara Sea. Internal bores followed by a packet of short-period internal waves are found in both directions from the strait. Satellite images show that short-period internal waves are generated after the internal bore. A hydraulic jump was found on the eastern side of the strait. Numerical modeling agrees with the experimental results.     

喀拉海峡潮-地相互作用激发非线性内波的数值模拟

Nonlinear internal waves(NIWs) are ubiquitous around the Kara Sea, a part of the Arctic Ocean that is north of Siberia. Three hot spot sources for internal waves, one of which is the Kara Strait, have been identified based on Envisat ASAR. The generation and evolution of the NIWs through the interactions of the tide and topography across the strait is studied based on a nonhydrostatic numerical model. The model captures most wave characteristics shown by satellite data. A typical inter-packets distance on the Barents Sea side is about 25 km in summer, with a phase speed about 0.65 m/s. A northward background current may intensify the accumulation of energy during generation, but it has little influence on the other properties of the generated waves. The single internal solitary wave(ISW) structure is a special phenomenon that follows major wave trains, with a distance about 5–8 km. This wave is generated with the leading wave packets during the same tidal period. When a steady current toward the Kara Sea is included, the basic generation process is similar, but the waves toward the Kara Sea weaken and display an internal bore-like structure with smaller amplitude than in the control experiment. In winter, due to the growth of sea ice, stratification across the Kara Strait is mainly determined by the salinity, with an almost uniform temperature close to freezing. A pycnocline deepens near the middle of the water depth(Barents Sea side), and the NIWs process is not as important as the NIWs process in summer. There is no fission process during the simulation.     

热带太平洋海温异常对北极海冰的可能影响

本文利用1950-2015年间Hadley环流中心海冰和海温资料及NCEP/NCAR再分析资料,研究了热带太平洋海温异常对北极海冰的可能影响,并从大气环流和净表面热通量两个角度探讨了可能的物理机制。结果表明,在ENSO事件发展年的夏、秋季节,EP型与CP型El Niño事件与北极海冰异常的联系无明显信号。而La Niña事件期间北极海冰出现显著异常,并且EP型与CP型La Niña之间存在明显差异。EP型La Niña发生时,北极地区巴伦支海、喀拉海关键区海冰异常减少,CP型La Niña事件则对应着东西伯利亚海、楚科奇海地区海冰异常增加。在EP型La Niña发展年的夏、秋季节,热带太平洋海温异常通过遥相关波列,使得巴伦支海、喀拉海海平面气压为负异常并与中纬度气压正异常共同构成类似AO正位相的结构,形成的风场异常有利于北大西洋暖水的输入,同时造成暖平流,偏高的水汽含量进一步加强了净表面热通量收入,使得巴伦支海、喀拉海海冰异常减少。而在CP型La Niña发展年的夏季,东西伯利亚海、楚科奇海关键区受其东侧气旋式环流的影响,以异常北风分量占主导,将海冰从极点附近由北向南输送到关键区,海冰异常增加,而净表面热通量的作用较小。     

末次盛冰期以来巴伦支海-喀拉海古海洋环境及海冰研究进展

巴伦支海-喀拉海是北冰洋最大的边缘海,能够对环境变化做出快速的响应和反馈,是全球气候变化最为敏感的区域之一,其古海洋环境演变及海冰变化研究是全球气候变化研究的重要组成部分。末次盛冰期以来,该区域的古海洋环境受到太阳辐射、海流强度、海平面变化、温盐环流和河流输入等因素影响发生了一系列不同尺度的波动。巴伦支海受到北大西洋暖水和极地冷水两大水团相互作用的影响,在水团交界处 （极锋) 由于不同水团性质的差异,导致其海水温度、盐度及海冰发生剧烈变化。而喀拉海则受到叶尼塞河和鄂毕河大量淡水输入影响,海流系统较巴伦支海相对复杂,沉积物主要来源于河流输入的陆源物质,并可以通过磁化率的分析明确区分两条河流的陆源物质。由于受到冷水和暖水的相互作用,巴伦支海-喀拉海海冰变化迅速,并且在全新世中晚期存在 0.4 ka 和 0.95 ka 的变化周期,但海冰变化的影响因素并不是单一的,而是气候系统内部各因子相互作用的结果。目前古海冰重建研究工作主要为定性研究,定量研究相对较少,所选用的重建指标也相对单一,另外存在年代框架差、分辨率低等不足。本文以巴伦支海和喀拉海为中心,总结了其快速气候突变事件、古温度盐度、海平面及海冰的变化,对影响因素进行了探讨,并通过分析末次盛冰期以来古海洋环境研究的不足,提出了相应的展望。     

The influence of long tides on ecosystem dynamics in the Barents Sea

The Barents Sea ecosystem has been associated with large biomass fluctuations. If there is a hidden deterministic process behind the Barents Sea ecosystem, we may forecast the biomass in order to control it. This presentation concludes, for the first time, investigations of a long data series from North Atlantic water and the Barents Sea ecosystem. The analysis is based on a wavelet spectrum analysis from the data series of annual mean Atlantic sea level, North Atlantic water temperature, the Kola section water temperature, and species from the Barents Sea ecosystem.The investigation has identified dominant fluctuations correlated with the 9.3-yr phase tide, the 18.6-yr amplitude tide, and a 74-yr superharmonic cycle in the North Atlantic water, Barents Sea water, and Arctic data series. The correlation between the tidal cycles and dominant Barents Sea ecosystem cycles is estimated to be R=0.6 or better. The long-term mean fluctuations correlate with the 74-yr superharmonic cycle. The wavelets analysis shows that the long-term 74-yr cycle may introduce a phase reversal in the identified 18-yr periods of temperature and salinity. The present analysis suggests that forced vertical and horizontal nodal tides influence the ocean's thermohaline circulation, and that they behave as a coupled non-linear oscillation system.The Barents Sea ecosystem analysis shows that the biomass life cycle and the long-term fluctuations correlate better than R=0.5 to the lunar nodal tide spectrum. Barents Sea capelin has a life cycle related to a third harmonic of the 9.3-yr tide. The life cycles of shrimp, cod, herring, and haddock are related to a third harmonic of the 18.6-yr tide. Biomass growth was synchronized to the lunar nodal tide. The biomass growth of zooplankton and shrimp correlates with the current aspect of lunar nodal tidal inflow to the Barents Sea. The long-term biomass fluctuation of cod and herring is correlated with a cycle period of about 3×18.6=55.8 yr. This analysis suggests that we may understand the Barents Sea ecosystem dynamic as a free-coupled oscillating system to the forced lunar nodal tides. This free-coupled oscillating system has a resonance related to the oscillating long tides and the third harmonic and superharmonic cycles.     

Atlantic Water flow through the Barents and Kara Seas

The pathway and transformation of water from the Norwegian Sea across the Barents Sea and through the St. Anna Trough are documented from hydrographic and current measurements of the 1990s. The transport through an array of moorings in the north-eastern Barents Sea was between 0.6 Sv in summer and 2.6 Sv in winter towards the Kara Sea and between zero and 0.3 Sv towards the Barents Sea with a record mean net flow of 1.5 Sv. The westward flow originates in the Fram Strait branch of Atlantic Water at the Eurasian continental slope, while the eastward flow constitutes the Barents Sea branch, continuing from the western Barents Sea opening.About 75% of the eastward flow was colder than 0°C. The flow was strongly sheared, with the highest velocities close to the bottom. A deep layer with almost constant temperature of about −0.5°C throughout the year formed about 50% of the flow to the Kara Sea. This water was a mixture between warm saline Atlantic Water and cold, brine-enriched water generated through freezing and convection in polynyas west of Novaya Zemlya, and possibly also at the Central Bank. Its salinity is lower than that of the Atlantic Water at its entrance to the Barents Sea, because the ice formation occurs in a low salinity surface layer. The released brine increases the salinity and density of the surface layer sufficiently for it to convect, but not necessarily above the salinity of the Atlantic Water. The freshwater west of Novaya Zemlya primarily stems from continental runoff and at the Central Bank probably from ice melt. The amount of fresh water compares to about 22% of the terrestrial freshwater supply to the western Barents Sea. The deep layer continues to the Kara Sea without further change and enters the Nansen Basin at or below the core depth of the warm, saline Fram Strait branch. Because it is colder than 0°C it will not be addressed as Atlantic Water in the Arctic Ocean.In earlier decades, the Atlantic Water advected from Fram Strait was colder by almost 2 K as compared to the 1990s, while the dense Barents Sea water was colder by up to 1 K only in a thin layer at the bottom and the salinity varied significantly. However, also with the resulting higher densities, deep Eurasian Basin water properties were met only in the 1970s. The very low salinities of the Great Salinity Anomaly in 1980 were not discovered in the outflow data. We conclude that the thermal variability of inflowing Atlantic water is damped in the Barents Sea, while the salinity variation is strongly modified through the freshwater conditions and ice growth in the convective area off Novaya Zemlya.     

A comparative analysis of the Harpacticoida (Copepoda) faunas from the northern and southern seas of Russia

Based on extensive voluminous literary data, a comparison of the Harpacticoida faunas of the Black Sea; the Sea of Azov; and the Caspian, Baltic, Barents, White, Kara, Laptev, and East Siberian seas, as well as of the Spitsbergen and Franz Josef Land areas, was performed. The degree of community and specificity of the faunas of different regions was estimated and the general patterns of the latitudinal variability in the species compositions were revealed. It is shown that the Harpacticoida faunas of geographically separated areas and even those isolated from each other such as those of the Black Sea, the Sea of Azov, and the Caspian Sea are rather similar; an hypothesis is put forward that this is caused by the common history of the seas’ formation. In contrast, the faunas of the Arctic seas (Barents, White, Kara, Laptev, and East Siberian), whose water areas are closely connected, are considerably different, being related to their different temperature conditions.     

基于GOCI影像的半月潮周期内渤海悬浮泥沙浓度变化研究

悬浮泥沙浓度(SSC)的变化对渤海海域的生态等有着重要的影响.本文基于已有表层水体SSC遥感反演算法进行了优化,利用较高时空分辨率的GOCI影像,基于优化后的模型对渤海表层水体的SSC浓度在半月潮周期中的时空分布与变化特征进行了研究.结果 表明:(1)渤海各海湾表层水体SSC在半月潮周期内的变化规律存在差异.从小潮到大...     

Coastal dynamics at the Barents and Kara Sea key sites

The results of permafrost and coastal dynamics investigations at four key sites on the shores of the Kara and Barents Seas are discussed. Three ACD key sites, Marre-Sale, Shpindler, and Kolguev, characterize areas with active thermal erosion; key site Cape Bolvansky is found on a relatively stable coast. It is found that the coastal retreat rate has spatial and temporal variability, which is typical of the entire Arctic coast. Coastal deposits on the Kara and Barents Seas have a low organic carbon content. Annual input of material into the Kara Sea resulting from coastal degradation reaches 35–40 million t, including about 7.5 million t of ice, 0.35 million t of organic carbon, and 0.3 million t of soluble salts.This revised version was published online January 2005 with corrections to the title of the article.     

Geodynamics of the Russian Arctic Shelf and Relief-Forming Processes in the Central Kara Basin

Oceanology - The article deals with the issues of the geodynamic evolution of the Kara–Barents Sea shelf and influence of structure-forming processes on the nature of relief formation. The...     

北极各海域海冰覆盖范围的变化特征

Sea ice in the Arctic has been reducing rapidly in the past half century due to global warming.This study analyzes the variations of sea ice extent in the entire Arctic Ocean and its sub regions.The results indicate that sea ice extent reduction during 1979–2013 is most significant in summer,following by that in autumn,winter and spring.In years with rich sea ice,sea ice extent anomaly with seasonal cycle removed changes with a period of 4–6 years.The year of 2003–2006 is the ice-rich period with diverse regional difference in this century.In years with poor sea ice,sea ice margin retreats further north in the Arctic.Sea ice in the Fram Strait changes in an opposite way to that in the entire Arctic.Sea ice coverage index in melting-freezing period is an critical indicator for sea ice changes,which shows an coincident change in the Arctic and sub regions.Since 2002,Region C2 in north of the Pacific sector contributes most to sea ice changes in the central Aarctic,followed by C1 and C3.Sea ice changes in different regions show three relationships.The correlation coefficient between sea ice coverage index of the Chukchi Sea and that of the East Siberian Sea is high,suggesting good consistency of ice variation.In the Atlantic sector,sea ice changes are coincided with each other between the Kara Sea and the Barents Sea as a result of warm inflow into the Kara Sea from the Barents Sea.Sea ice changes in the central Arctic are affected by surrounding seas.     

Simulation of surface and internal semidiurnal tides in the Kara Sea

The problem of the dynamics of surface and internal waves M ₂ in the Kara Sea is solved within the QUODDY-4 3D finite-element hydrostatic model. It is shown that the conventional concept of surface-tide wave generation due to the interaction of two tidal waves (one arrives from the Barents Sea and the other is generated in the Arctic Ocean (AO) and propagates southward along the west coasts of Severnaya Zemlya) is only partially valid: the east branch of the tidal wave generated in the AO actually exists, but there is also a west branch that propagates along the St. Anna trough and another tidal wave that penetrates in the Kara Sea from the Laptev Sea through the Vilkitsky Strait. Simulated spatial distributions of the tidal velocities, amplitudes of internal tidal waves at the pycnocline depth, and some components of the budgets of barotropic and baroclinic tidal energy are discussed.     

Circulation in the southwestern part of the Kara Sea in September 2007

During cruise 54 of the R/V Akademik Mstislav Keldysh to the southwestern Kara Sea (September 6 to October 7, 2007), a large amount of hydrophysical data with unique spatial resolution was obtained on the basis of measurements using different instruments. The analysis of the data gave us the possibility to study the dynamics and hydrological structure of the southwestern Kara Sea basin. The main elements of the general circulation are the following: the Yamal Current, the Eastern Novaya Zemlya Current, and the St. Anna Trough Current. All these currents are topographically controlled; they flow over the bottom slopes along the isobaths. The Yamal Current begins at the Kara Gates Strait and turns to the east as part of the cyclonic circulation. Then, it turns to the north and propagates along the Yamal coast over the 100-m isobath. The Eastern Novaya Zemlya Current (its core is located over the eastern slope of the Novaya Zemlya Trough) flows to the northeast. Near the northern edge of Novaya Zemlya, it encounters the St. Anna Trough Current, separates from the coast, and flows practically to the east merging with the continuation of the Yamal Current. A strong frontal zone is formed in the region where the two currents merge above the threshold that separates the St. Anna Trough from the Novaya Zemlya Trough and divides the warm and saline Arctic waters from the cooler and fresher waters of the southwestern part of the Kara Sea. This threshold, whose depth does not exceed 100–150 m, is a barrier that prevents the spreading of the Barents Sea and Arctic waters to the southwestern part of the Kara Sea basin through the St. Anna Trough.     

利用综合评分方法评估CMIP5模式对北极海冰的模拟能力

北极海冰冰盖自20世纪以来经历了前所未有的缩减,这使得北极海冰异常对大气环流的反馈作用日益显现。尽管目前的气候模式模拟北极海冰均为减少的趋势,但各模式间仍然存在较大的分散性。为了评估模式对于北极海冰变化及其气候效应的模拟能力,我们将海冰线性趋势和年际异常两者结合起来构造了一种合理的衡量指标。我们还强调巴伦支与卡拉海的重要性,因为前人研究证明此区域海冰异常是近年来影响大尺度大气环流变异的关键因子。根据我们设定的标准,CMIP5模式对海冰的模拟可被归为三种类型。这三组多模式集合平均之间存在巨大的差异,验证了这种分组方法的合理性。此外,我们还进一步探讨了造成模式海冰模拟能力差别的潜在物理因子。结果表明模式所采用的臭氧资料集对海冰模拟能力有显著的影响。     

Observed storminess patterns and trends in the circum-Arctic coastal regime

Storm event statistics for the open-water season (June–October) were extracted from the terrestrial-based observational record throughout the circumpolar coastal regime over the period 1950–2000. The Barents/Norwegian and Kara regions exhibited an active spring/quiet summer signature typical of the mid-latitudes. The Kara and Laptev Sea regions had a strong June peak possibly associated with early sea ice breakup. The Chukchi sector exhibited large storm power values (defined as speed²*duration). Storm counts declined from 1950 to 1970, shifted rapidly from 1970 to 1974 to a level of greater mean activity and greater inter-annual variability, and declined after 1988.     

Chlorophyll,primary production,and organic carbon fluxes in the Kara Sea

New maps of the mean monthly distribution of chlorophyll and the primary production in the Kara Sea were compiled using joint processing of CZCS (1978–1986), SeaWiFS (1998–2005), and MODIS (2002–2006) satellite data and field measurements. The annual primary production of phytoplankton is estimated at 22.3 × 10⁶ t of C per year or 70 mg of C/m² per day. The results of the calculations of the organic carbon budget in the Kara Sea are presented.     

Dynamics of the long-period tides

The long-period tides are a tool for understanding oceanic motions at low frequencies and large scales. Here we review observations and theory of the fortnightly, monthly and pole tide constitutents. Observations have been plagued by low signal-to-noise ratios and theory by the complex lateral geometry and great sensitivity to bottom slopes. A new spectral element model is used to compute the oceanic response to tidal forcing at 2-week and monthly periods. The general response is that of a heavily damped (Q ≈ 5) system with both the energy input from the moon and the dissipation strongly localized in space. The high dissipation result is probably generally applicable to all low frequency barotropic oceanic motions. Over much of the ocean, the response has both the character of a large-scale and a superposed Rossby wave-like character, thus vindicating two apparently conflicting earlier interpretations. To the extent that free waves are excited they are consistent with their being dominated by Rossby and topographic Rossby wave components, although gravity modes are also necessarily excited to some degree. In general, a modal representation is not very helpful. The most active regions are the Southern Ocean and the western and northern North Atlantic. These results are stable to changes in geometry, topography, and tide period. On a global average basis, the dynamical response of Mm is closer to equilibrium than is Mf.     

基于背景场的一种新的赤潮监测算法

Remote sensing has been proven to be an effective means of monitoring red tides. The spectral information is an important basis for establishing a model to monitor red tides. The spectral curves of red tide events are analyzed and compared with multiyear monthly averaged spectral curves based on MODIS data from July 2002 to June 2012, as well as spectral differences at the same location during red tide presence and absence. A red tide monitoring algorithm is developed based on the background field to extract the red tide information of the East China Sea （ECS）. With the application of the algorithm in the ECS, the results reveal that the developed model can effectively determine the location of red tides, with good correspondence to the results from an official bulletin. This demonstrates that the algorithm can effectively extract the red tide information.     

北极秋季海冰减少与亚洲大陆冬季温度异常

本文使用SVD等诊断分析方法探讨北极秋季海冰密集度与亚洲冬季温度异常之间的关系。结果表明,近30余年来,北极秋季海冰减少伴随着亚洲大陆冬季温度降低,但青藏高原地区、北冰洋和北太平洋沿岸除外。北极秋季海冰密集度减小激发欧亚大陆和北冰洋北部两个区域位势高度的改变,这种异常的变化模态从秋季持续到冬季。位势高度异常的负值中心位于巴伦支海和喀拉海。位势高度异常的正值中心位于蒙古区域。与重力位势高度异常伴随的风场异常为亚洲冬季温度降低提供自北向南的冷气流。随着北极海冰的不断减少,其与亚洲大陆冬季温度降低之间的关系将为气候长期预测提供参考。     

Isotope parameters (δD, δ<Superscript>18</Superscript>O) and sources of freshwater input to Kara Sea

The isotope characteristics (δD, δ¹⁸О) of Kara Sea water were studied for quantitative estimation of freshwater runoff at stations located along transect from Yamal Peninsula to Blagopoluchiya Bay (Novaya Zemlya). Freshwater samples were studied for glaciers (Rose, Serp i Molot) and for Yenisei and Ob estuaries. As a whole, δD and δ¹⁸O are higher in glaciers than in river waters. isotope composition of estuarial water from Ob River is δD =–131.4 and δ18O =–17.6‰. Estuarial waters of Yenisei River are characterized by compositions close to those of Ob River (–134.4 and–17.7‰), as well as by isotopically “heavier” compositions (–120.7 and–15.8‰). Waters from studied section of Kara Sea can be product of mixing of freshwater (δD =–119.4, δ¹⁸O =–15.5) and seawater (S = 34.9, δD = +1.56, δ¹⁸O = +0.25) with a composition close to that of Barents Sea water. isotope parameters of water vary significantly with salinity in surface layer, and Kara Sea waters are desalinated along entire studied transect due to river runoff. concentration of freshwater is 5–10% in main part of water column, and <5% at a depth of >100 m. maximum contribution of freshwater (>65%) was recorded in surface layer of central part of sea.