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1.
The problem of simulating sea dynamics in areas comprising near-shore zones and zones of high turbulence is considered. A mathematical model and the numerical algorithm of its solving are formulated. The model is based on the equations for nonhydrostatic dynamics and includes (k-ε) and (k-ω) parameterization of turbulent processes. The equations of the model are written in a σ-coordinate system. The numerical algorithm for solving the problem is based on the use of implicit schemes owing to the splitting with respect to the physical processes and space coordinates. The model calculations were performed for four nested sea basins with different spatial resolution: the Baltic Sea (3.7-km space resolution), the Gulf of Finland (1.85-km resolution), the Tallinn-Helsinki area (560-m resolution), and Tallinn Bay (93-m resolution). The results of the experiment show that the model well simulates the processes of enhanced turbulent activity in the near-shore zones that affect the local features of the sea characteristics. 相似文献
2.
V. L. Dorofeev G. K. Korotaev L. I. Sukhikh 《Izvestiya Atmospheric and Oceanic Physics》2013,49(6):622-631
Using an interdisciplinary three-dimensional physical and biogeochemical model developed for the Black Sea, the long-term evolution of marine dynamics and ecosystem is investigated. The hydrophysical fields were calculated from a model of Black Sea circulation with assimilation of hydrographic survey and satellite measurement data from 1971 to 2001. The circulation model reproduces well processes of various scales in both space and time (particularly the seasonal course and interannual variability of main hydrophysical fields). The resulting flow fields are then used to calculate the long-term evolution of the components of the lower level of the food chain in the Black Sea ecosystem. The biogeochemical model used in the calculations is based on the nitrogen cycle and includes a parameterization of the main biological and chemical interactions and processes in the upper layer of the Black Sea. The numerical experiments indicated that the biogeochemical component of the model rather successfully reproduces the main features and evolution trends in the Black Sea ecosystem for the period under consideration: the growth in the phytoplankton biomass during eutrophication and changes in seasonal cycles of the main ecosystem components. Also, the hydrophysical processes were shown to be important for a reliable reproduction of long-term changes in the ecosystem. 相似文献
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4.
H. Österblom A. Gårdmark L. Bergström B. Müller-Karulis C. Folke M. Lindegren M. Casini P. Olsson R. Diekmann T. Blenckner C. Humborg C. Möllmann 《Marine Policy》2010
Effectively reducing cumulative impacts on marine ecosystems requires co-evolution between science, policy and practice. Here, long-term social–ecological changes in the Baltic Sea are described, illustrating how the process of making the ecosystem approach operational in a large marine ecosystem can be stimulated. The existing multi-level governance institutions are specifically set up for dealing with individual sectors, but do not adequately support an operational application of the ecosystem approach. The review of ecosystem services in relation to regime shifts and resilience of the Baltic Sea sub-basins, and their driving forces, points to a number of challenges. There is however a movement towards a new governance regime. Bottom-up pilot initiatives can lead to a diffusion of innovation within the existing governance framework. Top-down, enabling EU legislation, can help stimulating innovations and re-organizing governance structures at drainage basin level to the Baltic Sea catchment as a whole. Experimentation and innovation at local to the regional levels is critical for a transition to ecosystem-based management. Establishing science-based learning platforms at sub-basin scales could facilitate this process. 相似文献
5.
《Marine Policy》2013
Marine environments and the ecosystem services they provide are threatened throughout the world. Using an extensive data set obtained from a coordinated survey across all nine littoral countries, this study examines the recreational use of and public perceptions towards the Baltic Sea, providing support for marine policies, including the European Union Marine Strategy Framework Directive. The findings indicate that the Baltic Sea is an important recreation area for residents of the littoral states, as the majority of people spend leisure time there. Swedes, Danes and Finns use the sea the most, and the most common activities are beach recreation and swimming. People are concerned over the state of the Baltic Sea, especially in Finland, Russia and Sweden. Poles, Danes and Finns have the most positive attitude towards contributing financially to improving the state of the Baltic Sea. Additional coordinated research efforts across all nine littoral countries are needed to quantify the monetary benefits of improving the state of the sea. However, even the present results provide evidence on the cultural importance of the Baltic Sea, suggesting that policy makers need to take stronger action to sustain the provision of recreational ecosystem services and safeguarding the well-being of marine ecosystems to the current and future generations. 相似文献
6.
Salt-water inflows into the Baltic Sea are important events for renewing the deep and bottom waters of the deep basins of the Baltic Sea. These events occur only at irregular intervals. The last strong event was in January 1993 followed by minor inflows in winter 1993/1994. As a result of these inflows, the deep water of the central Baltic basins was completely renewed.Based on extensive observations of polycyclic aromatic hydrocarbons (PAHs) in water, fluffy layer material and surface sediments between 1992 and 1998, the transformation of PAHs and the modification of their distribution in the Baltic deep water is discussed in connection with the spreading of the inflowing highly saline and oxygen-rich water along its pathway from the sills into the central basins. In the course of the inflows in 1993/1994, the PAH concentration in the deep water of the different basins increased significantly. The concentrations were elevated, at least by a factor of 2 and as much as seven to eight times (for the four-ring PAHs) compared to the previous and the following years. Two hypotheses for the causes were discussed: the inflowing salt water may have entrained more highly polluted surface water in the western Baltic Sea, or it may have entrained contaminated fluffy layer material or sediment particles along the route of transport. 相似文献
7.
A. N. Lukyanova A. V. Bagaev V. A. Ivanov V. B. Zalesny 《Izvestiya Atmospheric and Oceanic Physics》2017,53(6):624-631
The Black Sea shelf is a region of intense manifestation of various dynamical processes. Under the influence of different natural forces, eddy-wave phenomena develop here, which influence the general circulation of sea waters, biological productivity, and the condition of the engineering structures. Modern numerical models allow us to simulate and analyze the processes of the joint dynamics of marine circulation and large-scale waves. In this work, we study the spatiotemporal spectral characteristics of the sea level and velocity fluctuations formed due to atmospheric forcing and tidal potential. The hydrophysical fields are calculated using the Institute of Numerical Mathematics, Russian Academy of Sciences (INM RAS), σ model based on primitive equations. We use the CORE data as atmospheric forcing at the sea surface; the tidal potential is described by the semidiurnal lunar constituent M2. Analyzing the simulation results makes it possible to emphasize that accounting for the semidiurnal tidal potential not only improves the accuracy of the sea-level calculation at coastal stations, but also generates subinertial baroclinic oscillations previously found in the Black Sea from the data of in situ observations. 相似文献
8.
The governments around the Baltic Sea have agreed on a new set of targets for nutrient load reductions. The major motive for this is new and better knowledge about the link between nutrient loads and water transparency in different parts of the sea. The Baltic Sea Action Plan (BSAP) defines target for transparency in different marine basins, the load reductions necessary to meet transparency targets and a scheme for the distribution of the abatement burden between countries adjacent to the sea. 相似文献
9.
随着海洋生态系统模型的发展，生态变量增多，众多生物过程参数量值的确定成为制约生态环境模拟的瓶颈问题，生态系统结构区域性要求模型中的生态参数具有区域差异。为探究不同海区的关键参数及参数敏感度的空间差异，本研究在渤、黄海建立了ROMS-CoSiNE物理–生物耦合的高分辨率生态系统模型，并对13种生态参数的敏感度空间分布进行分析。结果表明:南黄海中部与渤海及近岸海域的敏感度差异较大。渤海敏感度最大的参数为决定光合速率的浮游植物P-I曲线初始斜率，其次为浮游动物捕食半饱和常数和浮游动物最大捕食率。而南黄海中部敏感度最大的参数为浮游动物最大捕食率，其次为浮游植物死亡率和浮游植物P-I曲线初始斜率。结合敏感度分布及浮游植物生物量收支得出，渤海水体透明度较南黄海偏低、浮游植物生长光限制较强，是引起浮游植物P-I曲线初始斜率敏感度在渤海高于黄海的主要原因。浮游动物最大捕食率及浮游植物死亡率的敏感度空间差异，受渤、黄海浮游植物生物量差异的影响，与生态系统中的高度非线性特征有关。 相似文献
10.
Overview of eutrophication indicators to assess environmental status within the European Marine Strategy Framework Directive 总被引：1，自引：0，他引：1
João G. Ferreira Jesper H. Andersen Angel Borja Suzanne B. Bricker Jordi Camp Margarida Cardoso da Silva Esther Garcés Anna-Stiina Heiskanen Christoph Humborg Lydia Ignatiades Christiane Lancelot Alain Menesguen Paul Tett Nicolas Hoepffner Ulrich Claussen 《Estuarine, Coastal and Shelf Science》2011
11.
海洋生态系统动力学模型作为定量地认识和分析海洋生态系统现象的有力工具,近年来得到了长足发展。本文首先回顾了海洋生态动力学模型的发展历史,着重介绍了21世纪以来生态系统动力学模型的三大发展趋势:一是进一步探索海洋生态系统复杂性,二是全球气候变化与海洋生态系统的相互作用;三是不再局限于理论研究,而进入于灾害预报与评估、公共决策等应用领域。其次介绍了海洋生态动力学模型的分类及典型海洋生态动力学数值模型COHERENS的特点、功能和最新的应用情况。最后总结归纳了目前海洋生态动力学模型研究领域的几大问题与挑战,展望了该研究领域未来的发展趋势和方向。 相似文献
12.
The grain-size and chemical composition of the bottom sediments and their diatom assemblages from the northern Baltic Sea is discussed. Characteristic layers are distinguished based on the lithostratgraphy and sediment core correlation, which reflect the transition from the lacustrine to marine sedimentation settings during the initial Holocene. Sediment cores demonstrate lateral variations in the sedimentation patterns during the marine (Yoldia Sea), the lacustrine (Ancylus Lake), and the subsequent marine (Littorina Sea) stages: first two stages were characterized by the clay deposition, while the latter one featured accumulation of silty-clayey and clayey muds in bottom depressions. Sea-level fluctuations and corresponding environmental changes are recorded in microlaminated sequences, in particular, sapropelic muds. 相似文献
13.
《Marine Policy》2013
The shift from a classic sector-by-sector management system to an operational ecosystem approach is perceived as the way forward towards sustainable use of marine systems. The nine states bordering the Baltic Sea as well as the European Community signed the Baltic Sea Action Plan (BSAP) in 2007, intended to provide practical means for implementing the ecosystem approach in the region. However, whether this shift towards a new governance approach also constitutes a case of institutional change remains unclear. This study evaluates institutional change over 30 years in order to understand the process of emergence of the ecosystem approach for this international institution. This study adds to the otherwise largely theoretical debate on institutional change by testing two models of institutional change – gradualist versus punctuated equilibrium – against data from the Helsinki Commission. Relying on a novel methodology involving quantitative text analyses of 574 documents this study suggests that the signing of the BSAP did not cause change in the institution, nor was it the cause of an abrupt institutional change. Overall, findings support a gradualist model of institutional change where the BSAP is layered upon preexisting institutional structures. Results also indicate that institutional change has occurred in some parts of the institution, whereas other parts remain remarkably stable. It proves that in order to intentionally change an institution it is vital that the change processes cohere at all levels of the institution. The study also underlines the mismatch between ecosystems and institutions. Given the relatively slow dynamics identified here, it is unclear whether institutions are able to adapt to rapid and unpredictable ecosystem shifts. 相似文献
14.
Shelf seas such as the North Sea and the Baltic Sea are characterised by spatially and temporally varying stratification that is highly relevant for their physical dynamics and the evolution of their ecosystems. Stratification may vary from unstably stratified (e.g., due to convective surface cooling) to strongly stratified with density jumps of up to 10 kg/m3 per m (e.g., in overflows into the Baltic Sea). Stratification has a direct impact on vertical turbulent transports (e.g., of nutrients) and influences the entrainment rate of ambient water into dense bottom currents which in turn determine the stratification of and oxygen supply to, e.g., the central Baltic Sea. Moreover, the suppression of the vertical diffusivity at the summer thermocline is one of the limiting factors for the vertical exchange of nutrients in the North Sea. Due to limitations of computational resources and since the locations of such density jumps (either by salinity or temperature) are predicted by the model simulation itself, predefined vertical coordinates cannot always reliably resolve these features. Thus, all shelf sea models with a predefined vertical coordinate distribution are inherently subject to under-resolution of the density structure.To solve this problem, Burchard and Beckers (2004) and Hofmeister et al. (2010) developed the concept of vertically adaptive coordinates for ocean models, where zooming of vertical coordinates at locations of strong stratification (and shear) is imposed. This is achieved by solving a diffusion equation for the position of the coordinates (with the diffusivity being proportional to the stratification or shear frequencies). We will show for a coupled model system of the North Sea and the Baltic Sea (resolution ∼ 1.8 km) how numerical mixing is substantially reduced and model results become significantly more realistic when vertically adaptive coordinates are applied. We additionally demonstrate that vertically adaptive coordinates perform well in simulating the two dynamically different regions North Sea and Baltic Sea with a single parameter set.An analysis of the computational overhead of the adaptive coordinates indicates an increase of 5–8% in runtime. This is still less expensive than adding more sigma-layers to reduce spurious numerical mixing. 相似文献
15.
Structure of the basins of the White Sea rift systems 总被引：1，自引：0，他引：1
For the first time, the structure of the sedimentary basins of the Late Proterozoic rift system in the White Sea is characterized based on a set of new marine geological geophysical data such as the results of the common depth point seismic method, gravity and magnetic data, and seismoacoustics. The main tectonic structures in the topography of the heterogeneous basement within the basin of the White Sea are distinguished and described. A structural tectonic scheme of the basement surface is presented. The thicknesses of the sediments are estimated and the stratigraphic confinement of the seismic units recognized is done. 相似文献
16.
The surface waves in the Baltic Sea are hindcast with the spectral wave model HYPAS during a 12-month period. The model results show a strong temporal and spatial variation in the wave field due to the physical dimensions of the different basins and the predominant wind field. The highest waves in the area are found in the outer part of Skagerrak, as well as in the central and southern parts of the Baltic Proper. To get significant waves above 6 m high, strong winds (15–20 m/s) must have been blowing for 6 to 24 h from a favourable direction over a deep area. 相似文献
17.
The shelfbreak wintertime thermal front in the Northeastern Gulf of Mexico often exhibits meandering, eddy formation and warm-water
intrusion. A high level of frontal variability plays an essential role in exchange processes across the shelf. This study
examines the impacts of local frontal instability and bottom topography on turbulent heat exchange across the front using
the results of two numerical models. Analysis of a series of numerical experiments reveals that the flow is baroclinically
unstable. Predicted frontal instability contributes significantly to cross-frontal exchange and accounts for about 35% of
the total eddy heat flux. Onshore eddy heat flux has the highest intensity at the frontal position. In addition, eddy activity
and heat flux are sensitive to variation of bottom topography. For topographic features and frontal characteristics that are
typical of the area, bottom steepness enhances the flux and is nearly proportional to the cross-frontal heat exchange. The
study attempts to explain physical mechanisms that drive frontal circulation in the area and to quantify heat transport across
the shelf. Estimated heat fluxes can provide important information for climate and ecosystem modeling of the Mississippi Bight. 相似文献
18.
With improved observation methods, increased winter navigation, and increased awareness of the climate and environmental changes, research on the Baltic Sea ice conditions has become increasingly active. Sea ice has been recognized as a sensitive indicator for changes in climate. Although the inter-annual variability in the ice conditions is large, a change towards milder ice winters has been detected from the time series of the maximum annual extent of sea ice and the length of the ice season. On the basis of the ice extent, the shift towards a warmer climate took place in the latter half of the 19th century. On the other hand, data on the ice thickness, which are mostly limited to the land-fast ice zone, basically do not show clear trends during the 20th century, except that during the last 20 years the thickness of land-fast ice has decreased. Due to difficulties in measuring the pack-ice thickness, the total mass of sea ice in the Baltic Sea is, however, still poorly known. The ice extent and length of the ice season depend on the indices of the Arctic Oscillation and North Atlantic Oscillation. Sea ice dynamics, thermodynamics, structure, and properties strongly interact with each other, as well as with the atmosphere and the sea. The surface conditions over the ice-covered Baltic Sea show high spatial variability, which cannot be described by two surface types (such as ice and open water) only. The variability is strongly reflected to the radiative and turbulent surface fluxes. The Baltic Sea has served as a testbed for several developments in the theory of sea ice dynamics. Experiences with advanced models have increased our understanding on sea ice dynamics, which depends on the ice thickness distribution, and in turn redistributes the ice thickness. During the latest decade, advance has been made in studies on sea ice structure, surface albedo, penetration of solar radiation, sub-surface melting, and formation of superimposed ice and snow ice. A high vertical resolution has been found as a prerequisite to successfully model thermodynamic processes during the spring melt period. A few observations have demonstrated how the river discharge and ice melt affect the stratification of the oceanic boundary layer below the ice and the oceanic heat flux to the ice bottom. In general, process studies on ice–ocean interaction have been rare. In the future, increasingly multidisciplinary studies are needed with close links between sea ice physics, geochemistry and biology. 相似文献
19.
海洋生态学和生物海洋学的研究内容大多交叉、重叠。为利于学科发展,文章在简述学科的产生与定义的基础上,强调学科之间要加强合作,适当分工。建议:海洋生态学侧重研究生物之间的相互关系和对环境的适应性、生存策略,并积极与经济、社会和文化相关学科交叉、融合;生物海洋学侧重于研究生物在海洋环境中的作用和功能,把推进对海洋的认识放在首位,加强与物理海洋学、化学海洋学的耦合,为海洋在地球四大圈层的相互关系中展现活力。据此,以渔业海洋学、海洋生态灾害和生物对地质的作用为例,阐述海洋生态学和生物海洋学的理解及其相互之间关系。 相似文献
20.
S. Allen Macklin George L. Hunt Jr. James E. Overland 《Deep Sea Research Part II: Topical Studies in Oceanography》2002,49(26)
Two Bering Sea marine research programs collaborated during the final years of the 1990s to forge advances in understanding the southeastern Bering Sea pelagic ecosystem. Southeast Bering Sea Carrying Capacity, sponsored by NOAA Coastal Ocean Program, investigated processes on the middle and outer shelf and the continental slope. The Inner Front Program, sponsored by NSF, investigated processes of the inner domain and the front between the inner and middle domains. The purposes of these programs were to (1) increase understanding of the southeastern Bering Sea ecosystem, including the roles of juvenile walleye pollock, (2) investigate the hypothesis that elevated primary production at the inner front provides a summer-long energy source for the food web, and (3) develop and test annual indices of pre-recruit pollock abundance. The observations occurred during a period of unusually large variability in the marine climate, including a possible regime shift. Sea-ice cover ranged from near zero to one of the heaviest ice years in recent decades. Sea-surface temperatures reached record highs during summer 1997, whereas 1999 was noted for its low Bering Sea temperatures. Moreover, the first recorded observations of coccolithophore blooms on the shelf were realized in 1997, and these blooms now appear to be persistent. The programs’ results include an archive of physical and biological time series that emphasize large year-to-year regional variability, and an Oscillating Control Hypothesis that relates marine productivity to climate forcing. Further investigations are needed of the confluences of interannual and even intra-seasonal variability with low-frequency climate variability as potential producers of major, abrupt changes in the southeastern Bering Sea ecosystem. 相似文献